Predicting The Future With Faces

“Your future will be horrible, but at least it will be short. So there’s that”

The future is always uncertain, at least as far as human (and non-human) knowledge is concerned. This is one reason why some people have difficulty saving or investing money for the future: if you give up rewards today for the promise of rewards tomorrow, that might end up being a bad idea if tomorrow doesn’t come for you (or a different tomorrow than the one you envisioned does). Better to spend that money immediately when it can more reliably bring rewards. The same logic extends to other domains of life, including the social. If you’re going to invest time and energy into a friendship or sexual relationship, you will always run the risk of that investment being misplaced. Friends or partners who betray you or don’t reciprocate your efforts are not usually the ones you want to be investing in the first place. You’d much rather invest that effort into the people who will give you better return.

Consider a specific problem, to help make this clear: human males face a problem when it comes to long-term sexual relationships, which is that female reproductive potential is limited. Not only can women only manage one pregnancy at a time, but they also enter into menopause later in life, reducing their subsequent reproductive output to zero. One solution to this problem is to only seek short-term encountered but, if you happen to be a man looking for a long-term relationship, you’d be doing something adaptive by selecting a mate with the greatest number of years of reproductive potential ahead of her. This could mean selecting a partner who is younger (and thus has the greatest number of likely fertile years ahead of her) and/or selecting one who is liable to enter menopause later.

Solving the first problem – age – is easy enough due to the presence of visual cues associated with development. Women who are too young and do not possess these cues are not viewed as attractive mates (as they are not currently fertile), become more attractive as they mature and enter their fertile years, and then become less attractive over time as fertility (both present and future) declines. Solving the second problem – future years of reproductive potential, or figuring out the age at which a woman will enter menopause – is trickier. It’s not like men have some kind of magic crystal ball they can look into to predict a woman’s future expected age at menopause to maximize their reproductive output. However, women do have faces and, as it turns out, those might actually be the next best tool for the job.

Fred knew it wouldn’t be long before he hit menopause

A recent study by Bovet et al (2017) sought to test whether men might be able to predict a woman’s age at menopause in advance of that event by only seeing her face. One obvious complicating factor with such research is that if you want to assess the extent to which attractiveness around, say, age 25 predicts menopause in the same sample of women, you’re going to have to wait a few decades for them to hit menopause. Thankfully, a work-around exists in that menopause – like most other traits – is partially heritable. Children resemble their partners in many regards, and age of menopause is one of them. This allowed the researchers to use a woman’s mother’s age of menopause as a reasonable proxy for when the daughter would be expected to reach menopause, saving them a lot of waiting. 

Once the participating women’s mother’s age of menopause was assessed, the rest of the study involved taking pictures of the women’s faces (N = 68; average age = 28.4) without any makeup and with as neutral as an expression as possible. These faces were then presented in pairs to male raters (N = 156) who selected which of the two was more attractive (completing that task a total of 30 times each). The likelihood of being selected was regressed against the difference between the mother’s age of menopause for each pair, controlling for facial femininity, age, voice pitch, waist-to-hip ratio, and a value representing the difference between a woman’s actual and perceived age (to ensure that women who looked younger/older than they actually were didn’t throw things off).

A number of expected results showed up, with more feminine faces (ß = 0.4) and women with more feminine vocal pitch (ß = 0.2) being preferred (despite the latter trait not being assessed by the raters). Women who looked older were also less likely to be selected (ß = -0.56) Contrary to predictions, women with more masculine WHRs were preferred (ß = 0.13), even though these were not visible in the photos, suggesting WHR may cue different traits than facial ones. The main effect of interest, however, concerned the menopausal variable. These results showed that as the difference between the pair of women’s mother’s age of menopause increased (i.e., one woman expected to go through menopause later than the other), so too did the probability of the later-menopausal woman getting selected (ß = 0.24). Crucially, there was no correlation between a woman’s expected age of menopause and any of the more-immediate fertility cues, like age, WHR, facial or vocal femininity. Women’s faces seemed to be capturing something unique about expected age at menopause that made them more attractive.

Trading off hot daughters for hot flashes

Now precisely what features were being assessed as more attractive and the nature of their connection to age of menopause is unknown. It is possible – perhaps even likely – that men were assessing some feature like symmetry that primarily signals developmental stability and health, but that variable just so happen to correlate with age at menopause as well (e.g., healthier women go through menopause later as they can more effectively bear the costs of childbearing into later years). Whatever systems were predicting age at menopause might not specifically be designed to do so. While it is possible that some features of a woman’s face uniquely cues people into expected age at menopause more directly without primarily cuing some other trait, that remains to be demonstrated. Nevertheless, the results are an interesting first step in that direction worth thinking about.

References: Bovet, J., Barkat-Defradas, M., Durand, V., Faurie, C., & Raymond, M. (2017). Women’s attractiveness is linked to expected age at menopause. Journal of Evolutionary Biology, doi: 10.1111/jeb.13214

What Can Chimps Teach Us About Strength?

You better not be aping me…

There was a recent happening in the primatology literature that caught my eye. Three researchers were studying patterns of mating in captive chimpanzees. They were interested in finding out what physical cues female chimps tended to prefer in a mate. This might come as no surprise to you – it certainly didn’t to me – but female chimps seemed to prefer physically strong males. Stronger males were universally preferred by the females, garnering more attention and ultimately more sexual partners. Moreover, strength was not only the single best predictor of attractiveness, but there was no upper-limit on this effect: the stronger the male, the more he was preferred by the females. This finding makes perfect sense in its proper evolutionary context, given chimps’ penchant for getting into physical conflicts. Strength is a key variable for males in dominating others, whether this is in the context of conflicts over resources, social status, or even inter-group attacks. Males who were better able to win these contests were not only likely to do well for themselves in life, but their offspring would likely be the kind of males who would do likewise. That makes them attractive mating prospects, at least if having children likely to survive and mate is adaptive, which it seems to be.

What interested me so much was not this finding – I think it’s painfully obvious – but rather the reaction of some other academics to it. These opposing reactions claimed that the primatologists were too quick to place their results in that evolutionary context. Specifically, it was claimed that these preferences might not be universal, and that a cultural explanation makes more sense (as if the two are competing types of explanations). This cultural explanation, I’m told, goes something like, “chimpanzee females are simply most attracted to male bodies that are the most difficult to obtain because that’s how chimps in this time and place do things,” and “if this research was conducted 100 years ago, you’d have observed a totally different pattern of results.”

Now why the difficulty in achieving a body is supposed to be the key variable isn’t outlined, as far as I can tell. Presumably it too should have some kind of evolutionary explanation which would make a different set of predictions, but none are outlined. This point seems scarcely realized by the critics. Moreover, the idea that these findings would not obtain 100 years ago is tossed out with absolutely no supporting evidence and little hope of being tested. It seems unlikely that physical strength yielding adaptive benefits is some kind of evolutionary novelty, or that males did not differ in that regard as little as a hundred years ago despite plenty of contemporary variance.

One more thing: the study I’m talking about didn’t take place on chimps. It was a pattern observed in humans. The underlying logic and reactions, however, are pretty much spot on.  

Not unlike this man’s posing game

It’s long been understood that strong men are more attractive than weak ones, all else being equal. The present research by Sell et al (2017) was an attempt to (a) quantify approximately how much of a man’s bodily attractiveness is driven by his physical strength, (b) the nature of this relationship (whether it is more of a straight line or an inverted “U” shape, where very strong men are less attractive, and (c) whether some women find weaker men more attractive than stronger ones. There was also a section about quantifying the effects of height and weight.

To answer those questions, pictures of semi-to-shirtless men were photographed from the front and side, and their heads were blocked out so only their bodies remained. These pictures were then assessed by different groups for either strength or attractiveness (actual strength measures were collected by the researchers). The quick run down of the results are that perceived strength did track actual strength, and perceptions of strength accounted for about 60-70% of the variance in bodily attractiveness (which is a lot). As men got stronger, they got more attractive, and this trend was linear (meaning that, within the sample, there was no such thing as “too strong” after which men got less attractive). This pattern was also universal: there was not a single women (out of 160) who rated the weaker men as more attractive than the stronger ones. Accounting for strength, height accounted for a bit more of the attractiveness, and weight was negatively related to attractiveness. Women liked strong men; not fat ones.

While it’s nice to put something of a number on just how much strength matters in determining male bodily attractiveness (most of it), these findings are all mundane to anyone with eyes. I suspect they cut across multiple species, and I don’t think you’re going to find just about any species where females prefer to mate with physically weaker males. The explanation for these preferences for strength – the evolutionary framework into which they fit – should apply well to just about any of the species in that list. While I initially made up the fact that this study was about chimps, I’d say you’re likely to find a similar set of results if you did conduct such work.

Also, the winner – not the loser – of this contest will go on to mate

Enter the strange comments I mentioned initially:

“It’s my opinion that the authors are too quick to ascribe a causal role to evolution,” said Lisa Wade…“We know what kind of bodies are valorized and idealized,” Wade said. “It tends to be the bodies that are the most difficult to obtain.”

Try reading that criticism of the study and imagine it was applied to any other sexually-reproducing species on the planet. What adaptive benefits is “difficulty in obtaining” supposed to bring and what kind of predictions does that idea make? It would be difficult, for instance, to achieve a very thin body; the type usually seen in anorexic people. It’s hard for people to ignore their desires to eat certain foods in certain quantities, especially to the point you begin to physically waste away. Despite that difficulty in achieving the starved look, such bodies are not idealized as attractive. “Difficult to obtain” does not necessary translate into anything adaptively useful. 

And, more to the point, even if a preference for difficult-to-obtain bodies per se existed, where would Lisa suggest it came from? Surely, it didn’t fall from the sky. The explanation for a preference for difficult bodies would, at some point, have to reference some kind of evolutionary history. It’s not even close to sufficient to explain a preference by saying, “culture, not evolution, did it,” as if the capacity for developing a culture itself – and any given instantiation of it -  exists free from evolution. Despite her claims to the contrary, it is a theoretical benefit to thinking about evolutionary function when developing theories of psychological form; not a methodological problem. The only problem I see is that she seems to prefer worse, less-complete explanations to better ones. But, to use her own words, this is “…nothing unique to [her]. Much of this type of [criticism] has the same methodological problems

If your explanation for a particular type of psychological happening in humans doesn’t work for just about any other species, there’s a very good chance it is incomplete when it comes to explaining the behavior at the very least. For instance, I don’t think anyone would seriously suggest that chimp females entering into their reproductive years “might not have much of an experience with what attractiveness means,” if they favored physically strong males. I’d say it’s fairly common such explanations aren’t even pointing in the right direction a lot of the time, and are more likely to mislead researchers and students than help inform them. 

References: Sell, A., Lukazsweki, A., & Townsley, M. (2017). Cues of upper body strength account for most of the variance in men’s bodily attractiveness. Proc. R. Soc. B 284http://dx.doi.org/10.1098/rspb.2017.1819

Online Games, Harassment, and Sexism

Gamers are no strangers to the anger that can accompany competition. As a timely for-instance, before I sat down to start writing this post I was playing my usual online game to relax after work. As I began playing my first game of the afternoon, I saw a message pop up from someone who had sent me a friend request a few days back after I had won a match (you need to accept these friend requests before messages can be sent). Despite the lag in between the time that request was sent and when I accepted it, the message I was greeted with called me a cunt and informed me that I have no life before the person removed themselves from my friend list to avoid any kind of response. However accurately they may have described me, that is the most typical reason friend requests get sent in that game: to insult. Many people – myself included – usually don’t accept them from strangers for that reason and, if you do, it is advisable to wait a few days for the sender to cool off a bit and hopefully forget they added you. Even then, that’s no guarantee of a friendly response.

Now my game happens to be more of a single-player experience. In team-based player vs player games, communication between strangers can be vital for winning, meaning there is usually less of a buffer between players and the nasty comments of their teammates. This might not draw much social attention, but these players being insulted are sometimes women, bringing us nicely to some research on sexism.

Gone are the simpler days of yelling at your friends in person

A 2015 paper by Kasumovic & Kuznekoff examined how players in the online, first-person shooter game Halo 3 responded to the presence of a male and female voice in the team voice chat, specifically in terms of both positive and negative comments directed at them. What drew me to this paper is two-fold: first, I’m a gamer myself but, more importantly, the authors also constructed their hypotheses based on evolutionary theory, which is unusual for papers on sexism. The heart of the paper revolves around the following idea: common theories of sexist behavior towards women suggest that men behave aggressively towards them to try and remove them from male-dominated arenas. Women get nasty comments because men want them gone from male spaces. The researchers in this case took a different perspective, predicting instead that male performance within the game would be a key variable in understanding the responses players have.

As men heavily rely on their social status for access to mating opportunities, the authors predicted they should be expected to respond more aggressively to newcomers into a status hierarchy that displace them. Put into practice, this means that a low-performing male should be threatened by the entry of a higher-performing woman into their game as it pushes them down the status hierarchy, resulting in aggression directed at the newcomers. By contrast, males that perform better should be less concerned by women in the game, as it does not undercut their status. Instead of being aggressive, then, higher-performing men might give female players more positive comments in the interests of attracting them as possible mates. Putting that together, we end up with the predictions that women should receive more negative comments than men from men who are performing worse, while women should receive more positive comments from men who are performing better.

To test this idea, the researchers played the game with 7 other random players (two teams of 4 players) while playing either male or female voice lines at various intervals during the game (all of which were pretty neutral-to-positive in terms of content, such as, “I like this map” played at the beginning of a game). The recordings of what the other players (who did not know they were being monitored in this way, making their behavior more natural) said were then transcribed and coded for whether they were saying something positive, negative, or neutral directed at the experimenter playing the game. The coders also checked to see whether the comments contained hostile sexist language to look for something specifically anti-woman, rather than just negativity or anger in general.

Nothing like some wholesome, gender-blind rage

Across 163 games, any other players spoke at all in 102 of them. In those 102 games, 189 players spoke in total, 100% of whom were male. This suggests that Halo 3, unsurprisingly, is a game that women aren’t playing as much as men. Only those players who said something and were on the experimenter’s team (147 of them) were maintained for analysis. About 57% of those comments were in the female-voiced condition, while 44% where in the male condition. In general, then, the presence of a female voice led to more comments from other male players.

In terms of positive comments, the predicted difference appeared: the higher the skill level of the player talking at the experimenter, the more positive comments they made when a woman’s voice was heard; the worse the player, the fewer positive comments they made. This interaction was almost significant when considering the relative difference, rather than the absolute skill rating (i.e. Did the player talking do worse or better than the experimenter). By contrast, the number of positive comments directed at the male-voiced player was unrelated to the skill of the speaker.

Turning to the negative comments, it was found that they were negatively correlated with player skill in general: the higher the skill of the player, the fewer negative comments they made (and the lower the skill, the more negative they got. As the old saying goes, “Mad because bad”). The interaction with gender was less clear, however. In general, the teammates of the female-voiced experimenter made more negative comments than in the male condition. When considering the impact of how many deaths a speaking player had, the players were more negative towards the woman when dying less, but they were also more negative towards the man when dying extremely often (which sees to run counter to the initial predictions). The players were also more negative towards a women when they weren’t getting very many kills (with negativity towards the woman declining as their personal kills increased), but that relationship was not observed when they had heard a male voice (which is in line with the initial predictions).

Finally, only a few players (13%) made sexist statements, so the results couldn’t be analyzed particularly well. Statistically, these comments were unrelated to any performance metrics. Not much more to say about that beyond small sample size.  

Team red is much more supportive of women in gaming

Overall, the response that speaking players had to the gender of their teammate depended, to some extent, on their personal performance. Those men who were doing better at the game were more positive towards the women, while those who were doing worse were more negative towards them, generally speaking.

While there are a number of details and statements within the paper I could nitpick, I suspect that Kasumovic & Kuznekoff (2015) are on the right track with their thinking. I would add some additional points, though. The first of these is rather core to their hypothesis: if men are threatened by status losses brought on by their relative poor performance, it seems that these threats should occur regardless of the sex of the person they’re playing with: whether a man performs poorly relative to a woman or another man, he will still be losing relative status. So why is there less negativity directed at men (sometimes), relative to women? The authors mention one possibility that I wish they had expanded upon more, which is that men might be responding not to the women per se as much as the pitch of the speaker’s voice. As the authors write, voice pitch tends to correlate with dominance, such that deeper voices tend to correlate with increased dominance.

What I wish they had added more explicitly is that aggression should not be deployed indiscriminately. Being aggressive towards people who are liable to beat you in a physical contest isn’t a brilliant strategy. Since men tend to be stronger than women, behaving aggressively towards other men – especially those outperforming you – should be expected to have carried different sets of immediate consequences, historically-speaking (though there aren’t many costs in modern online environments, which is why people behave more aggressively there than in person). It might not be that the men are any less upset about losing when other men are on their team, but that they might not be equally aggressive (in all cases) to them due to potential physical retribution (again, historically).

There are other points I would consider beyond that. The first of these is the nature of insults in general. If you remember the interaction I had with an angry opponent initially, you should remember that the goal of their message was to insult me. They were trying to make me feel bad or in some way drag me down. If you want to make someone feel bad, you would do well to focus on their flaws and things about them which make you look better by comparison. In that respect, insulting someone by calling attention to something you share in common, like your gender, is a very weak insult. On those grounds we might expect more gendered insults against women, given that men are by far the majority in these games. Now because lots of hostile sexist insults weren’t observed in the present work, the point might not be terribly applicable here. It does, however, bring me to my next point: you don’t insult people by bringing attention to things that reflect positively on them.

“Ha! That loser can only afford cars much more expensive than I can!”

As women do not play games like Halo nearly as much as men, that corresponds to lower skill in those games on a population level. Not because women are inherently worse at the game but simply because they don’t practice them as much (and people who play those games more tend to become better at them). If you look at the top competitive performance in competitive online games, you’ll notice the rosters are largely, if not exclusively, male (not unlike all the people who spoke in the current paper). Regardless of the causes of that sex difference in performance, the difference exists all the same.

If you knew nothing else about a person beyond their gender, you would predict that a man would perform better at Halo than a woman (at least if you wanted your predictions to be accurate). As such, if you’ve just under-performed at this game and are feeling pretty angry about it, some players might be looking to direct blame at their teammates who clearly caused the issue (as it would never be their the speaker’s skill in the game, of course. At least not if you’re talking about the people yelling at strangers).

If you wanted to find out who was to blame, you might consult the match scores: factors like kills and deaths. But those aren’t perfect representations of player skill (that nebulous variable which is hard to get at) and they aren’t the only thing you might consult. After all, scores in a singular game are not necessarily indicative of what would happen over a larger number of games. Because of that, the players on these teams still have limited information about the relative skill of their teammates. Given this lack of information, some people may fall back on generally-accurate stereotypes in trying to find a plausible scapegoat for their loss, assigning relatively more blame for the loss to the people who might be expected to be more responsible for it. The result? More blame assigned to women, at least initially, given the population-level knowledge.

“I wouldn’t blame you if I knew you better, so how about we get to know each other over coffee?”

That’s where the final point I would add also comes in. If women perform worse on a population level than men, the low-performing men suffer something of a double status hit when they are outperformed by a woman: not only is there another player who is doing better than them, but one might expect this player to be doing worse, knowing only their gender. As such, being outperformed by such a player makes it more difficult to blame external causes for the outcome. In a sentence, being beaten by someone who isn’t expected to perform well is a more honest signal of poor skill. The result, then, is more anger: either in an attempt to persuade others that they’re better than they actually performed or in an attempt to get the people out of there who are making them look even worse. This would fit within the author’s initial hypothesis as well, and would probably have been worth mentioning.

References: Kasumovic, M. & Kuznekoff, J. (2015). Insights into sexism: Male status and performance moderates female-directed hostile and amicable behavior. PLoS ONE 10(7). doi:10.1371/journal.pone.0131613

Practice, Hard Work, And Giving Up

There’s no getting around it: if you want to get better at something – anything – you need to practice. I’ve spent the last several years writing rather continuously and have noticed that my original posts are of a much lower quality when I look back at them. If you want to be the best version of yourself that you can be, you’ll need to spend a lot of time working at your skills of choice. Nevertheless, people do vary widely in terms of how much practice they are willing to devote to a skill and how readily they abandon their efforts in the face of challenges, or simply to time. Some musicians will wake up and practice several hours a day, some only a few days a week, some a few times throughout the year, and some will stop playing entirely (in spite of almost none of them making anything resembling money from it). In a word, some musicians possess more grit than others.

Those of us who spend too much time at a computer acquire a different kind of grit

To give you a sense for what is meant by grit, consider the following description offered by Duckworth et al (2007):

The gritty individual approaches achievement as a marathon; his or her advantage is stamina. Whereas disappointment or boredom signals to others that it is time to change trajectory and cut losses, the gritty individual stays the course.

Grit, in this context, refers to those who continue to pursue their goals when faced with obstacles, major or minor. According to Duckworth et al (2007), this trait of grit is referenced regularly by people discussing the top performers in their field about as often as talent, even if they might not refer to it by that name.

The aim of the Duckworth et al (2007) paper, broadly speaking, was two-fold: to create a scale to measure grit (as one did not currently exist), and then use that scale to see how well grit predicted subsequent achievements. Without going too in depth into the details of the project, the grit scale eventually landed on 12 questions. Six of those dealt with how consistent one’s interests are (like, “my interests change from year to year”) and the other six with perseverance of effort (like, “I have overcome setbacks to conquer an important challenge”). While this measure of grit was highly correlated with the personality trait of conscientiousness (r = .77), the two were apparently different enough to warrant separate categorization, as the grit score still predicted some outcomes after controlling for personality.

When the new scale was directed at student populations, grit was also found to relate to educational achievement, controlling for measures of general intelligence: in this case, college GPA controlling for SAT scores in a sample of about 1,400 Upenn undergraduates. The relationship between grit and GPA was modest (r = .25), though it got somewhat larger after controlling for SAT scores (r = .34). In a follow-up study, the grit scale was also used to predict which cadets at a military academy completed their summer training. Though about 94% of the cadets completed this training, these grittiest individuals were the least likely to drop out, as one might expect. However, unlike in the Upenn sample, grit was not a good predictor of subsequent cadet GPA in that sample (r = .06), raising some questions about the previous result (which I’ll get to in a minute).

This is time not spent studying for that engineering test

With that brief summary of grit in mind – hopefully enough to give you a general sense for the term – I wanted to discuss some of the theoretical aspects of the idea. Specifically, I want to consider when grit might be a good thing and when it might be better to persevere a little less or find new interests.

One big complication stopping people from being gritty is the simple matter of opportunity costs. For every task I decide to invest years of dedicated, consistent practice to, there are other tasks I do not get to accomplish. Time spent writing this post is time I don’t get to spend pursuing other hobbies (which I have been taking intermediate breaks to pursue, for the record). This is, in fact, why I have begun writing a post every two weeks or so down from each week: there are simply other things in life I want to spend my time on. Being gritty about writing means I don’t get to be equally gritty about other things. In fact, if I were particularly gritty about writing I might not get to be gritty about anything at all. Not unless I wanted to stop being gritty about sleep, but even then I could just devote that sleeping time to writing as well.

This is a problem when it comes to grit being useful, because of a second issue: diminishing returns on practice. That first week, month, or year you spend learning a skill typically yields a more appreciable return than the second, third, or so on. Putting that into a quick example, if I started studying chess (a game I almost never play), I would see substantial improvements to my win rate in the first month. Let’s just say 10% to put a number on it. The next month of practice still increases my win rate, but not by quite as much, as there are less obvious mistakes I’m making. I go up another 5%. As this process continues, I might eventually spend a month of practice to increase my win rate by mere fractions of a percent. While this dedicated practice does, on paper, make me better, the size of those rewards relative to the time investment I need to make to get them gets progressively smaller. At a certain point, it doesn’t make much more sense to commit that time to chess when I could be learning to speak Spanish or even just spend that time with friends.

This brings us nicely to the next point: the rate of improvement, both in terms of how quickly you learn and how far additional practice can push you, ought to depend on one’s biological potential (for lack of a better term). No matter how much time I spend practicing guitar, for instance, there are certain ceilings on performance I will not be able to break: perhaps it becomes physically impossible to play any faster while maintaining accuracy; perhaps some memory constraints come into play and I cannot remember everything I’ve tried to learn. We should expect grit to interact with potential in a certain way: if you don’t have the ability to achieve a particular task, being gritty about pursuing it is going to be time spent effectively banging your head against a brick wall. By contrast, the individual who possesses a greater potential for the task in question has a much higher chance of grit paying off. They can simply get more from practice.

Some people just have nicer ceilings than others

This is, of course, assuming the task is actually one that can be accomplished. If you’re very gritty about finding the treasure buried in your backyard that doesn’t actually exist, you’ll spend a lot of time digging and none getting rich. Being gritty about achieving the impossible is a bad idea. But who’s to say what’s impossible? We usually don’t have access to enough information to say something cannot (or at least will not) be achieved, but we can often make some fairly-educated guesses. Let’s just stick to the music example for now: say you want to accomplish the task of becoming a world-famous rockstar. You have the potential to perform and you’re very gritty about pursuing it. You spend years practicing, forming bands, writing songs, finding gigs, and so on. One problem you’re liable to encounter in this case is simply that many other people who are similarly qualified are doing likewise, and there’s only so much room at the top. Even if you are all approximately as talented and gritty, there are some ceiling effects at play where being even grittier and more talented does not, by any means, guarantee more success. As I have mentioned before, the popularity of cultural products can be a fickle thing. It’s not just about the products you produce or what you can do. 

We see this playing out in the world of academia today. As many have lamented, there seem to be too few academic jobs for all the PhDs getting minted across the country. Being gritty about pursuing that degree – all the time, energy, and money spent earning it – turned out to not be a great idea for many who have done so. Sure, you can bet that just about everyone who achieved their dream job as a professor making a decent salary was pretty gritty about things. You have to be if you’re going to spend 10 or more years invested in higher education with little payoff and many challenges along the way. It’s just that lots of people who were about as gritty as those who got a job failed to do anything with their degree after they achieved it. As this example shows, not only does the task need to be achievable, but the rewards for achieving it need to be both valuable and likely if grit is to pay off. If the rewards aren’t valuable (eg, a job as an adjunct teaching 5 courses a semester for about as much as you’d make working minimum wage, all things considered), then pursuing them is a bad idea. If the rewards are valuable but unlikely (eg, becoming a top-selling pop artist), then pursuing them is similarly a bad idea for just about everyone. There are better things to do with your time.

The closest most people will come to being a rockstar

This yields the following summary: for grit to be potentially useful, a task needs to be capable of being accomplished, you need the potential to accomplish it given enough time, the rewards of achieving it need to be large enough, relative to the investment you put in, and the probability of achieving those rewards is comparably high. While that does leave many tasks for which passionate persistence and practice might pay off (and many for which it will not), this utility always exists in the context of other people doing likewise. For that reason, beyond a certain ceiling of effort more is not necessarily much of a guarantee of success. You can think of grit as – in many cases – something of a prerequisite for success rather than a great determinant. Finally, all of that needs to be weighed against the other things you could be doing with your time. Time spent being gritty about sports is time not spent being gritty about academics, which is time not spent being gritty about music, and so on.

If you want to reach your potential within a domain, there’s really no other option. You’ll need to invest lots of time and effort. Figuring out where that effort should go is the tricky part.

References: Duckworth, A., Peterson, C, Matthews, M., & Kelly, D. (2007). Grit: Perseverance and passion for long-term goals. Journal of Personality & Social Psychology, 92, 1087-1101.

Understanding Sex In Advertising

When people post videos on YouTube, one major point of interest for content creators and aggregators is to capture as much attention as possible. Your video is adrift in a sea of information and you’re trying to get as many eyes/clicks on your work as possible. In that realm, first impressions are all important: you want your video to have an attention-grabbing thumbnail image, as that will likely be the only thing viewers see before they actually click (or don’t) on it. So how do people go about capturing attention in that realm? One popular method is to ensure their thumbnail has a very emotive expression on it; a face of shock, embarrassment, stress, or any similar emotion. That’s certainly one way of attracting attention: trying to convince people there is something worth looking at, not unlike articles titled along the lines of five shocking tips for a better sex life (and number 3 will blow your mind!). Speaking of sex, that’s another popular method of grabbing attention: it’s fairly common for video thumbnails to feature people or body parts in various stages of undress. Not much will pull eyes towards a video like the promise of sex (and if you’re feeling an urge to click on that link, you’ll have experienced exactly what I’m talking about).

Case in point: most of that content is unrelated to the featured women

If sex happens to be attention grabbing, the natural question arises concerning what you might do with that attention once you have it. Much of the time, that answer will involve selling some good or service. In other words, sex is used as a form of advertising to try and sell things. “If you enjoyed that picture of a woman wearing a thong, you’ll surely love our reasonably-costed laptops!”. Something along those lines, anyway. Provided that’s your goal, lots of questions naturally start to crop up: How effective is sex at these goals? Does it capture attention well? Does it help people notice and remember your product or brand? Are those who viewed your sexy advert more likely to buy the product you’re selling? How do other factors – the sex of the person viewing the ad – contribute to your success in these realms?

These are some of the questions examined in a recent meta-analysis by Wirtz, Sparks, & Zimbres (2017). The researchers searched the literature and found about 80 studies, representing about 18,000 participants. They sought to find out what effects featuring sexually provocative material had, on average (defined in terms of style of dress, sexual behavior, innuendo, or sexual embeds, which is where hidden messages or images are placed within the ad, like the word “sex” added somewhere to the picture, which is something people apparently think is a good idea sometimes). These ads had to have been compared against a comparable, non-sexual ad for the same product to be included in the analysis to determine which was more effective.

The effectiveness of these ads were assessed across a number of domains as well, including ad recognition (in aided and unaided contexts), whether the brand being advertised in the ad could be recalled (i.e., were people paying attention to just the sex, or did they remember the product?), the positive or negative response people had to the ad, what people thought about the brand being advertised with sex, and whether the ad actually got them interested in purchasing the product (does sex sell?).

Finally, a number of potentially moderating factors that might influence these effects were considered. The first of these was gender: did these ads have different impacts on men and women? Others factors included the gender of the model used in the advertisement, the date the article was published (to see if attitudes shifted over time), the sample used (college students or not), and – most interestingly – product/ad congruity: did the type of product being advertised matter when it came to whether sex was effective? Perhaps sex might help sell a product like sun-tan lotion (as the beach might be a good place to pick up mates), but be much less effective for selling, say, laptops.

Maybe even political views

In terms of capturing attention, sex works. Of the 20 effects looking at the recall for ads, the average size was d = .38. Interesting, this effect was slightly larger for the congruent ads (d = .45), but completely reversed for the incongruent ones (d = -.45). Sex was good at getting people to remember ads selling a sex-related product, but not just generally useful. That said, they seemed better at getting people to remember just the ads. When the researchers turned to the matter of whether the brands within the ads were more likely to be recalled, the 31 effects looking at brand recognition turned out to barely break zero (d = .09). While sex might be attention-grabbing, it didn’t seem especially good at getting people to remember the objects being sold.

Regarding people’s attitudes towards the ads, sex seems like something of a wash (d = -.07). Digging a little deeper revealed a more nuanced pictured of these reactions, though: while sexual ads seemed to be a modest hit with the men (d = .27), they had the opposite effect on women (d = -.38). Women seemed to dislike the ads modestly more than men liked them, as sexual strategies theory would suggest (for the record, the type of model being depicted didn’t make much of a difference. In order, people liked males models the least (d = -.28), then female models (d = -.20), and couples were mildly positive, d = .08).

Curiously, both the men and women seemed to be agreement regarding their stance towards brands that used sex to sell things: negative, on the whole (d – =.22). For women, this makes some intuitive sense: they didn’t see to be a fan of the sexual ads, so they weren’t exactly feeling too ingratiated towards the brand itself. But why were the men negatively inclined towards the brand if they were favorably inclined towards the ads? I can only speculate on that front, but I assume it would have something to do with their inevitable disappointment: either that the brands were promising on sex the male customers likely knew they couldn’t deliver on, or perhaps the men simply wanted to enjoy the sex part and the brand itself ended up getting in their way. I can’t imagine men would be too happy with their porn time being interrupted by an ad for toilet paper or fruit snacks mid-video.

Finally, turning the matter of purchase intentions – whether the ads encouraged people to want to buy the product or not – it seemed that sex didn’t really sell, but it didn’t really seem to hurt, either (d = .01). One interesting exception in that realm was that sex appeals were actually less likely to get people to buy a product when the product being sold was incongruent with the sexual appeal (d = -.24). Putting that into a simple example, the phrase “strip club buffet” probably doesn’t wet many appetites, and wouldn’t be a strong selling point for such a venue. Sex can be something of a disease vector, and associating your food with that might illicit more than a bit of disgust.

“Oh good, I was starving. This seems like as good a place as any”

As I’ve noted before, context matching matters in advertising. If you’re looking to sell people something that highlights their individuality, then doing so in a mating context works better than in a context of fear (as animals aren’t exactly aiming to look distinct when predators are nearby). The same seems to hold for using sex. While it might be useful for getting eyes on your advertisement, sex is by no mean guaranteed to ensure that people like what they see once you have their attention. In that regard, sex – like any other advertising tool – needs to be used selectively, targeting the correct audience in the correct context if it’s going to succeed at increasing people’s interest in buying. Sex in general doesn’t sell. However, it might prove more effective for those with more promiscuous attitudes than those with more monogamous ones; it might prove useful if advertising a product related to sex or mating, but not useful for selling domain names (like the old GoDaddy commercials; coincidentally, GoDaddy was also the brand I used to register this site); it might work better if you associate your product with things that lead to sex (like status), rather than sex itself. These are all avenues worth pursuing further to see when, where, and why sex works or fails.

That said, it is still possible that sex might prove useful, even in some inappropriate contexts. Consider the following hypothetical example: people will consider buying a product only after they have seen an advertisement for it. Advertisement X isn’t sexual, but when paired with the product will increase people’s intentions to buy it by 10%. However, it will also not really get noticed by many people, as the content is bland. By contrast, advertisement Y is sexual, will decrease people’s intentions to buy a product by 10%, but will also get four-times as many eyes on it. The latter ad might well be more successful, as it will capture the eye of more potential customers that may still buy the product despite the inappropriate use of sexWhile targeting advertisements might be more effective, the attention model of advertising shouldn’t be ruled out entirely, especially if targeting advertising would prove too cumbersome.

References: Wirtz, J., Sparks, J., & Zimbres, T. (2017). The effect of exposure to sexual appeals in advertisements on memory, attitude, and purchase intention: A meta-analytic review. International Journal of Advertising, https://doi.org/10.1080/02650487.2017.1334996

 

Divorced Dads And Their Daughters

Despite common assumptions, parents have less of an impact on their children’s future development than they’re often credited with. Twins reared apart usually aren’t much different than twins reared together, and adopted children don’t end up resembling their adoptive parents substantially more than strangers. While parents can indeed affect their children’s happiness profoundly, a healthy (and convincing) literature exists supporting the hypothesis that differences in parenting behaviors don’t do a whole lot of shaping in terms of children’s later personalities (at least when the child isn’t around the parent; Harris, 2009). This makes a good deal of theoretical sense, as children aren’t developing to be better children; they’re developing to become adults in their own right. What children learn works when it comes to interacting with their parents might not readily translate to the outside world. If you assume your boss will treat you the same way your parents would, you’re likely in for some unpleasant clashes with reality. 

“Who’s a good branch manager? That’s right! You are!”

Not that this has stopped researchers from seeking to find ways that parent-child interactions might shape children’s future personalities, mind you. Indeed, I came upon a very new paper purporting to do just that this last week. It suggested that the quality of a father’s investment in his daughters causes shifts in his daughter’s willingness to engage in risky sexual behavior (DelPriore, Schlomer, & Ellis, 2017). The analysis in the paper is admittedly a bit tough to follow, as the authors examine three- and even four-way interactions (which are difficult to keep straight in one’s mind: the importance of variable A changes contingent on the interaction between B, C, & D), so I don’t want to delve too deeply into the specific details. Instead, I want to discuss the broader themes and design of the paper.

Previous research looking at parenting effects on children’s development often suffers from the problem of relatedness, as genetic similarities between parents and children make it hard to tease apart the unique effects of parenting behaviors (how the parents treat their children) from natural resemblances (nice parents have nice children). In a simple example, parents who love and nurture their children tend to have children who grow up kinder and nicer, while parents who neglect their children tend to have children who grow up to be mean. However, it seems likely that parents who care for their children are different in some important regards than those who neglect them, and those tendencies are perfectly capable of being passed on through shared genes. So are the nice kids nice because of how their parents treated them or because of inheritance? The adoption studies I mentioned previously tend to support the latter interpretation. When you control for genetic factors, parenting effects tend to drop out.

What’s good about the present research is its innovative design to try and circumvent this issue of genetic similarities between children and parents. To accomplish this goal, the authors examined (among other things) how divorce might affect the development of different daughters within the same family. The reasoning for doing so seems to go roughly as follows: daughters should base their sexual developmental trajectory, in part, on the extent of paternal investment they’re exposed to during their early years. When daughters are regularly exposed to fathers that invest in them and monitor their behavior, they should come to expect that subsequent male parental investment will be forthcoming in future relationships and avoid peers who engage in risky sexual behavior. The net result is that such daughters will engage in less risky sexual behavior themselves. By contrast, when daughters lack proper exposure to an investing father, or have one who does not monitor their peer behavior as tightly (due to divorce), they should come to view future male investment as unlikely, associate with those who engage in riskier sexual behavior, and engage in such behavior themselves.

Accordingly, if a family with two daughters experiences a divorce, the younger daughter’s development might be affected differently than the older daughter’s, as they have different levels of exposure to their father’s investment. The larger this age gap between the daughters, the larger this effect should be. After recruiting 42 sister pairs from intact families and 59 sister pairs from divorced families and asking them some retrospective questions about what their life was like growing up, this is basically the result the authors found. Younger daughters tended to receive less monitoring than older daughters in families of divorce and, accordingly, tended to associate with more sexually-risky peers and engage in such behaviors themselves. This effect was not present in biologically intact families. Do we finally have some convincing evidence of parenting behaviors shaping children’s personalities outside the home?

Look at this data and tell me the first thing that comes to your mind

I don’t think so. The first concern I would raise regarding this research is the monitoring measure utilized. Monitoring, in this instance, represented a composite score of how much information the daughters reported their parents had about their lives (rated from (1) didn’t know anything, (2) knew a little, or (3) knew a lot) in five domains: who their friends were, how they spent their money, where they spent their time after school, where they were at night, and how they spent their free time. While one might conceptualize that as monitoring (i.e., parents taking an active interest in their children’s lives and seeking to learn about/control what they do), it seems that one could just as easily think of that measure as how often children independently shared information with their parents. After all, the measure doesn’t specify, “how often did your parents try to learn about your life and keep track of your behavior?” It just asked about how much they knew.

To put that point concretely, my close friends might know quite a bit about what I do, where I go, and so on, but it’s not because they’re actively monitoring me; it’s because I tell them about my day voluntarily. So, rather than talking about how a father’s monitoring of his daughter might have a causal effect on her sexual behavior, we could just as easily talk about how daughters who engage in risky behavior prefer not to tell their parents about what they’re doing, especially if their personal relationship is already strained by divorce.

The second concern I have concerns divorce itself. Divorce can indeed affect the personal relationships of children with their parents. However, that’s not the only thing that happens after a divorce. There are other effects that extend beyond emotional closeness. An important example of these other factors are the financial ones. If a father has been working while the mother took care of the children – or if both parents were working – divorce can result in massive financial hits for the children (as most end up living with their mother or in a joint custody arrangement). The results of entering additional economic problems into an already emotionally-upsetting divorce can entail not only additional resentment between children and parents (and, accordingly, less sharing of information between them; the reduced monitoring), but also major alterations to the living conditions of the children. These lifestyle shifts could include moving to a new home, upsetting existing peer relations, entering new social groups, and presenting children with new logistical problems to solve.

Any observed changes in a daughter’s sexual behavior in the years following a divorce, then, can be thought of as a composite of all the changes that take place post-divorce. While the quality and amount of the father-daughter relationship might indeed change during that time, there are additional and important factors that aren’t controlled for in the present paper.

Too bad the house didn’t split down the middle as nicely

The final concern I wanted to discuss was more of a theoretical one, and it’s slightly larger than the methodological points above. According to the theory proposed at the beginning of the paper:

“…the quality of fathering that daughters receive provides information about the availability and reliability of male investment in the local ecology, which girls use to calibrate their mating behavior and expectations for long-term investment from future mates.”

This strikes me as a questionable foundation for a few reasons. First, it would require that the relationship of a daughter’s parents are substantially predictive of the relationships she is likely to encounter in the world with regard to male investment. In other words, if your father didn’t invest in your mother (or you) that heavily (or at least during your childhood), that needs to mean that many other potential fathers are likely to do the same to you (if you’re a girl). This would further require, then, that male investment be appreciably uniform across time in the world. If male investment wasn’t stable between males and across time within a given male, then trying to predict the general availability of future male investment from your father’s seems like a losing formula for accuracy.

It seems unlikely the world is that stable. For similar reasons, I suggested that children probably can’t accurately gauge future food availability from their access to food at a young age. Making matters even worse in this regard is that, unlike food shortages, the presence or absence of male parental investment doesn’t seem like the kind of thing that will be relatively universal. Some men in a local environment might be perfectly willing to invest heavily in women while others are not. But that’s only considering the broad level: men who are willing to invest in general might be unwilling to invest in a particular woman, or might be willing or unwilling to invest in that woman at different stages in her life, contingent on her mate value shifting with age. Any kind of general predictive power that could be derived about men in a local ecology seems weak indeed, especially if you are basing that decision off a single relationship: the one between your parents. In short, if you want to know what men in your environment are generally like, one relationship should be as informative as another. There doesn’t seem to be a good reason to assume your parents will be particularly informative.

Matters get even worse for the predictive power of father-daughter relationships when one realizes the contradiction between that theory and the predictions of the authors. The point can be made crystal clear simply by considering the families examined in this very study. The sample of interest was comprised of daughters from the same family who had different levels exposure to paternal investment. That ought to mean, if I’m following the predictions properly, that the daughters – the older and younger one – should develop different expectations about future paternal investment in their local ecology. Strangely, however, these expectations would have been derived from the same father’s behavior. This would be a problem because both daughters cannot be right about the general willingness of males to invest if they hold different expectations. If the older daughter with more years of exposure to her father comes to believe male investment will be available and the younger daughter with fewer years of exposure comes to believe it will be unavailable, these are opposing expectations of the world.

However, if those different expectations are derived from the same father, that alone should cast doubt on the ability of a single parental relationship to predict broad trends about the world. It doesn’t even seem to be right within families, let alone between them (and it’s probably worth mentioning at this point that, if children are going to be right about the quality of male investment in their local ecology more generally, all the children in the same area should develop similar expectations, regardless of their parent’s behavior. It would be strange for literal neighbors to develop different expectations of general male behavior in their local environment just because the parents of one home got divorced while the other stayed together. Then again, it should strange for daughters of the same home to develop different expectations, too).

Unless different ecologies have rather sharp boarders

On both a methodological and theoretical level, then, there are some major concerns with this paper that render its interpretation suspect. Indeed, at the heart of the paper is a large contradiction: if you’re going to predict that two girls from the same family develop substantially different expectations about the wider world from the same father, then it seems impossible that the data from that father is very predictive of the world. In any case, the world doesn’t seem as stable as it would need to be for that single data point to be terribly useful. There ought not be anything special about the relationship of your parents (relative to other parents) if you’re looking to learn something about the world in general.

While I fully expect that children’s lives following their parents divorce will be different – and those differences can affect development, depending on when they occur – I’m not so sure that the personal relationship between fathers and daughters is the causal variable of primary interest.

References: DelPriore, D., Schlomer, G., & Ellis, B. (2017). Impact of Fathers on Parental Monitoring of Daughters and Their Affiliation With Sexually Promiscuous Peers: A Genetically and Environmentally Controlled Sibling Study. Developmental Psychology. Advance online publication. http://dx.doi.org/10.1037/dev0000327

Harris, J. (2009) The Nurture Assumption: Why Children Turn Out the Way They Do. Free Press, NY.

Why Do So Many Humans Need Glasses?

When I was very young, I was given an assignment in school to write a report on the Peregrine Falcon. One interesting fact about this bird happens to be that it’s quite fast: when the bird spots prey (sometimes from over a mile away) it can enter into a high-altitude dive, reaching speeds in excess of 200 mph, and snatch its prey out of midair (if you’re interested in watching a video of such a hunt, you can check one out here). The Peregrine would be much less capable of achieving these tasks – both the location and capture of prey – if its vision was not particularly acute: failures of eyesight can result in not spotting the prey in the first place, or failing to capture it if distances and movements aren’t properly tracked. For this reason I suspect (though am not positive) that you’ll find very few Peregrines that have bad vision: their survival depends very heavily on seeing well. These birds would probably not be in need of corrective lens, like the glasses and contacts that humans regularly rely upon in modern environments. This raises a rather interesting question: why do so many humans wear glasses?

And why does this human wear so many glasses?

What I’m referring to in this case is not the general degradation of vision with age. As organisms age, all their biological systems should be expected to breakdown and fail with increasing regularity, and eyes are no exception. Crucially, all these systems should be expected to all breakdown, more-or-less, at the same time. This is because there’s little point in a body investing loads of metabolic resources into maintaining a completely healthy heart that will last for 100 years if the liver is going to shut down at 60. The whole body will die if the liver does, healthy heart (or eyes) included, so it would be adaptive to allocate those development resources differently. The mystery posed by frequently-poor human eyesight is appreciably different, as poor vision can develop early in life; often before puberty. When you observe apparent maladaptive development early in life like that, it requires another type of explanation.

So what might explain why human visual acuity appears so lackluster early in life (to the tune of over 20% of teenagers using corrective lenses)? There are a number of possible explanations we might entertain. The first of these is that visual acuity hasn’t been terribly important to human populations for some time, meaning that having poor eyesight did not have an appreciable impact on people’s ability to survive and reproduce. This strikes me as a rather implausible hypothesis on the face of it not only because vision seems rather important for navigating the world, but also because it ought to predict that having poor vision should be something of a species universal. While 20% of young people using corrective lenses is a lot, eyes (and the associated brain regions dedicated to vision) are costly organs to grow and maintain. If they truly weren’t that important to have around, then we might expect that everyone needs glasses to see better; not just pockets of the population. Humans don’t seem to resemble the troglobites that have lost their vision after living in caves away from sunlight for many generations.

Another possibility is that visual acuity has been important – it’s adaptive to have good vision – but people’s eyes fail to develop properly sometimes because of development insults, like infectious organisms. While this isn’t implausible in principle – infectious agents have been known to disrupt development and result in blindness, deafness, and even death on the extreme end – the sheer numbers of people who need corrective lenses seem a bit high to be caused by some kind of infection. Further, the numbers of younger children and adults who need glasses appear to have been rising over time, which might seem strange as medical knowledge and technologies have been steadily improving. If the need for glasses is caused by some kind of infectious agent, we would need to have been unaware of its existence and not accidentally treated it with antibiotics or other such medications. Further, we might expect glasses to be associated with other signs of developmental stress, like bodily asymmetries, low IQ, or other such outcomes. If your immune system didn’t fight off the bugs that harmed your eyes, it might not be good enough to fight off other development-disrupting infections. However, there seems to be a positive correlation between myopia and intelligence, which would be strange under a disease hypothesis.

The negative correlation with fashion sense begs for explanation, too

A third possible explanation is that visual acuity is indeed important for humans, but our technologies have been relaxing the selection pressures that were keeping it sharp. In other words, since humans invented glasses and granted those who cannot see as well a crutch to overcome this issue, any reproductive disadvantage associated with poor vision was effectively removed. It’s an interesting hypothesis that should predict people’s eyesight in a population begins to get worse following the invention and/or proliferation of corrective lenses. So, if glasses were invented in Italy around 1300, that should have lead to the Italian population’s eyesight growing worse, followed by the eyesight of other cultures to which glasses spread but not beforehand. I don’t know much about the history of vision across time in different cultures, but something tells me that pattern wouldn’t show up if it could be assessed. In no small part, that intuition is driven by the relatively-brief window of historical time between when glasses were invented, and subsequently refined, produced in sufficient numbers, distributed globally, and today. A window of only about 700 years for all of that to happen and reduce selection pressures for vision isn’t a lot of time. Further, there seems to be evidence that myopia can develop rather rapidly in a population, sometimes as quick as a generation:

One of the clearest signs came from a 1969 study of Inuit people on the northern tip of Alaska whose lifestyle was changing2. Of adults who had grown up in isolated communities, only 2 of 131 had myopic eyes. But more than half of their children and grandchildren had the condition. 

That’s much too fast for a relaxation of selection pressures to be responsible for the change.

This brings us to the final hypothesis I wanted to cover today: an evolutionary mismatch hypothesis. In the event that modern environments differ in some key ways from the typical environments humans have faced ancestrally, it is possible that people will develop along an atypical path. In this case, the body is (metaphorically) expecting certain inputs during its development, and if they aren’t received things can go poorly. As a for instance, it has been suggested that people develop allergies, in part, as a result of improved hygiene: our immune systems are expecting a certain level of pathogen threat which, when not present, can result in our immune system attacking inappropriate targets, like pollen.

There does seem to be some promising evidence on this front for understanding human vision issues. A paper by Rose et al (2008) reports on myopia in two samples of similarly-aged Chinese children: 628 children living in Singapore and 124 living in Sydney. Of those living in Singapore, 29% appeared to display myopia, relative to only 3% of those living in Sydney. These dramatic differences in rates of myopia are all the stranger when you consider the rates of myopia in their parents were quite comparable. For the Sydney/Singapore samples, respectively, 32/29% of the children had no parent with myopia, 43/43% had one parent with myopia, and 25/28% had two parents with myopia. If myopia was simply the result of inherited genetic mutations, its frequencies between countries shouldn’t be as different as they are, disqualifying hypotheses one and three from above.

When examining what behavioral correlates of myopia existed between countries, several were statistically – but not practically – significant, including number of books read and hours spent on computers or watching TV. The only appreciable behavioral difference between the two samples was the number of hours the children tended to spend outdoors. In Sydney, the children spent an average of about 14 hours a week outside, compared to a mere 3 hours in Singapore. It might be the case, then, that the human eye requires exposure to certain kinds of stimulation provided by outdoor activities to develop properly, and some novel aspects of modern culture (like spending lots of time indoors in a school when children are young) reduce such exposure (which might also explain the aforementioned IQ correlation: smarter children may be sent to school earlier). If that were true, we should expect that providing children with more time outdoors when they are young is preventative against myopia, which it actually seems to be.

Natural light and no Wifi? Maybe I’ll just go blind instead…

It should always strike people as strange when key adaptive mechanisms appear to develop along an atypical path early in life that ultimately makes them worse at performing their function. An understanding of what types of biological explanations can account for these early maladaptive outcomes goes a long way in helping you understand where to begin your searches and what patterns of data to look out for.

References: Rose, K., Morgan, I., Smith, W., Burlutsky, G., Mitchell, P., & Saw, S. (2008). Myopia, lifestyle, and schooling in students of Chinese ehtnicity in Singapore and Sydney. Archives of Ophthalmology, 126, 527-530.

Why Do We Roast The Ones We Love?

One very interesting behavior that humans tend to engage in is murder. While we’re far from the only species that does this (as there are some very real advantages to killing members of your species – even kin – at times), it does tend to garner quite a bit of attention, and understandably so. One very interesting piece of information about this interesting behavior concerns motives; why people kill. If you were to hazard a guess as to some of the most common motives for murder, what would you suggest? Infidelity is a good one, as is murder resulting from other deliberate crimes, like when a robbery is resisted or witnesses are killed to reduce the probability of detection. Another major factor that many might not guess is minor slights or disagreements, such as one person stepping on another person’s foot by accident, followed by an insult (“watch where you’re going, asshole!”), which is responded to with an additional insult, and things kind of get out of hand until someone is dead (Daly & Wilson, 1988). Understanding why seemingly minor slights get blown so far out of proportion is a worthwhile matter in its own right. The short-version of the answer as to why it happens is that one’s social status (especially if you’re a male) can be determined, in large part, by whether other people know they can push you around. If I know you will tolerate negative behavior without fighting back, I might be encouraged to take advantage of you in more extreme ways more often. If others see you tolerating insults, they too may exploit you, knowing you won’t fight back. On the other hand, if I know you will respond to even slight threats with violence, I have a good reason to avoid inflicting costs on you. The more dangerous you are, the more people will avoid harming you.

“Anyone else have something to say about my shirt?! Didn’t think so…”

This is an important foundation for understanding why another facet of human behavior is strange (and, accordingly, interesting): friends frequently insult each other in a manner intended to be cordial. This behavior is exemplified well by the popular Comedy Central Roasts, where a number of comedians will get together to  publicly make fun of each other and their guest of honor. If memory serves, the (unofficial?) motto of these events is, “We only roast the ones we love,” which is intended to capture the idea that these insults are not intended to burn bridges or truly cause harm. They are insults born of affection, playful in nature. This is an important distinction because, as the murder statistics help demonstrate, strangers often do not tolerate these kinds of insults. If I were to go up to someone I didn’t know well (or knew well as an enemy) and started insulting their drug habits, dead loved ones, or even something as simple as their choice of dress, I could reasonably expect anything from hurt feelings to a murder. This raises an interesting series of mysteries surrounding the matter of why the stranger might want to kill me but my friends will laugh, as well as when my friends might be inclined to kill me as well.

Insults can be spoken in two primary manners: seriously and in jest. In the former case, harm is intended, while in the latter it often isn’t. As many people can attest to, however, the line between serious and jesting insults is not always as clear as we’d like. Despite our best intentions, ill-phrased or poorly-timed jokes can do harm in much the same way that a serious insult can. This suggests that the nature of the insults is similar between the two contexts. As the function of a serious insult between strangers would seem to be to threaten or lower the insulted target’s status, this is likely the same function of an insult made in jest between friends, though the degree of intended threat is lower in those contexts. The closest analogy that comes to mind is the difference between a serious fight and a friendly tussle, where the combatants either are, or are not, trying to inflict serious harm on each other. Just like play fighting, however, things sometimes go too far and people do get hurt. I think joking insults between friends go much the same way.

This raises another worthwhile question: as friends usually have a vested interest in defending each other from outside threats and being helpful, why would they then risk threatening the well-being of their allies through such insults? It would be strange if they were all risk and reward, so it would be up to us to explain what that reward is. There are a few explanations that come to mind, all of which focus on one crucial facet of friendships: they are dynamic. While friendships can be – and often are – stable over time, who you are friends with in general as well as the degree of that friendship changes over time. Given that friendships are important social resources that do shift, it’s important that people have reliable ways of assessing the strength of these relationships. If you are not assessing these relationships now and again, you might come to believe that your social ties are stronger than they actually are, which can be a problem when you find yourself in need of social support and realize that you don’t have it. Better to assess what kind of support you have before you actually need it so you can tailor your behavior more appropriately.

“You guys got my back, right?….Guys?….”

Insults between friends can help serve this relationship-monitoring function. As insults – even the joking kind – carry the potential to inflict costs on their target, the willingness of an individual to tolerate the insult – to endure those costs – can serve as a credible signal for friendship quality. After all, if I’m willing to endure the costs of being insulted by you without responding aggressively in turn, this likely means I value your friendship more than I dislike the costs being inflicted. Indeed, if these insults did not carry costs, they would not be reliable indications of friendship strength. Anyone could tolerate behavior that didn’t inflict costs to maintain a friendship, but not everyone will tolerate behaviors that do. This yields another prediction: the degree of friendship strength can also be assessed by the degree of insults willing to be tolerated. In other words, the more it takes to “go too far” when it comes to insults, the closer and stronger the friendship between two individuals. Conversely, if you were to make a joke about your friend that they become incredibly incensed over, this might result in your reevaluating the strength of that bond: if you thought the bond was stronger than it was, you might either take steps to remedy the cost you just inflicted and make the friendship stronger (if you value the person highly) or perhaps spend less time investing in the relationship, even to the point of walking away from it entirely (if you do not).

Another possible related function of these insults could be to ensure that your friends don’t start to think too highly of themselves. As mentioned previously, friendships are dynamic things based, in part, on what each party can offer to the other. If one friend begins to see major changes to their life in a positive direction, the other friend may no longer be able to offer the same value they did previously. To put that in a simple example, if two friends have long been poor, but one suddenly gets a new, high-paying job, the new status that job affords will allow that person to make friends he likely could not before. Because the job makes them more valuable to others, others will now be more inclined to be their friend. If the lower-status friend wishes to retain their friendship with the newly-employed one, they might use these insults to potentially undermine the confidence of their friend in a subtle way. It’s an indirect way of trying to ensure the high-status friend doesn’t begin to think he’s too good for his old friends.

Such a strategy could be risky, though. If the lower-status party can no longer offer the same value to the higher-status one, relative to their new options, that might also not be the time to test the willingness of the higher-status one to tolerate insults. At the same time, times of change are also precisely when the value of reassessing relationship strength can be at its highest. There’s less of a risk of a person abandoning a friendship when nothing has changed, relative to when it has. In either case, the assessment and management of social relationships is likely the key for understanding the tolerance of insults from friends and intolerance of them from strangers.

“Enjoy your new job, sellout. You used to be cool”

This analysis can speak to another interesting facet of insults as well: they’re directed towards the speaker at times, referred to self-deprecating humor when done in jest (and just self-deprecation when not). It might seem strange that people would insult themselves, as it would act to directly threaten their own status. That people do so with some regularity suggests there might be some underlying logic to these self-directed insults as well. One possibility is that these insults do what was just discussed: signal that one doesn’t hold themselves in high esteem and, accordingly, signal that one isn’t “too good” to be your friend. This seems like a profitable place from which to understand self-depreciating jokes. When such insults directed towards the self are not made in jest, they likely carry additional implications as well, such as that expectations should be set lower (e.g., “I’m really not able to do that”) or that one is in need of additional investment, relative to the joking kind. 

References: Daly, M. & Wilson, M. (1988). Homicide. Aldine De Gruyter: NY.

Semen Quality And The Menstrual Cycle

One lesson I always try to drive home in any psychology course I teach is that biology (and, by extension, psychology) is itself costly. The usual estimate on offer is that our brains consume about 20% of our daily caloric expenditure, despite making up a small portion of our bodily mass. That’s only the cost of running the brain, mind you; growing and developing it adds further metabolic costs into the mix. When you consider the extent of those costs over a lifetime, it becomes clear that – ideally – our psychology should only be expected to exist in an active state to the extent it offers adaptive benefits that tend to outweigh them. Importantly, we should also expect that cost/benefit analysis to be dynamic over time. If a component of our biology/psychology is useful during one point in our lives but not at another, we might predict that it would switch on or off accordingly. This line of thought could help explain why humans are prolific language learners early in life but struggle to learn a second language in their teens and beyond; a language-learning mechanism active during development it would be useful up to a certain age for learning a native tongue, but later becomes inactive when its services are no longer liable to required, so to speak (which they often wouldn’t be in an ancestral environment in which people didn’t travel far enough to encounter speakers of other languages).

“Good luck. Now get to walking!”

The two key points to take away from this idea, then, are (a) that biological systems tend to be costly and, because of that, (b) the amount of physiological investment in any one system should be doled out only to the extent it is likely to deliver adaptive benefits. With those two points as our theoretical framework, we can explain a lot about behavior in many different contexts. Consider mating as a for instance. Mating effort intended to attract and/or retain a partner is costly to engage in (in terms of time, resource invest, risk, and opportunity costs), so people should only be expected to put effort into the endeavor to the extent they view it as likely to produce benefits. As such, if you happen to be a hard “5″ on the mating market, it’s not worth your time pursuing a mate that’s a “9″ because you’re probably wasting your effort; similarly, you don’t want to pursue a “3″ if you can avoid it, because there are better options you might be able to achieve if you invest your efforts elsewhere.

Speaking of mating effort, this brings us to the research I wanted to discuss today. Sticking to mammals just for the sake of discussion, males of most species endure less obligate parenting costs than females. What this means is that if a copulation between a male and female results in conception, the female bears the brunt of the biological costs of reproduction. Many males will only provide some of the gametes required for reproduction, while the females must provide the egg, gestate the fetus, birth it, and nurse/care for it for some time. Because the required female investment is substantially larger, females tend to be more selective about which males they’re willing to mate with. That said, even though the male’s typical investment is far lower than the female’s, it’s still a metabolically-costly investment: the males need to generate the sperm and seminal fluid required for conception. Testicles need to be grown, resources need to be invested into sperm/semen production, and that fluid needs to be rationed out on a per-ejaculation basis (a drop may be too little, while a cup may be too much). Put simply, males cannot afford to just produce gallons of semen for fun; it should only be produced to the extent that the benefits outweigh the costs.

For this reason, you tend to see that male testicle size varies between species, contingent on the degree of sperm competition typically encountered. For those not familiar, sperm competition refers to the probability that a female will have sperm from more than one male in her reproductive tract at a time when she might conceive. In a concrete sense, this translates into a fertile female mating with two or more males during her fertile window. This creates a context that favors the evolution of greater male investment into sperm production mechanisms, as the more of your sperm are in the fertilization race, the greater your probability of beating the competition and reproducing. When sperm competition is rare (or absent), however, males need not invest as many resources into mechanisms for producing testes and they are, accordingly, smaller.

Find the sperm competition

This logic can be extended to matters other than sperm competition. Specifically, it can be applied to cases where a male is (metaphorically) deciding how much to invest into any given ejaculate, even if he’s the female’s only sexual partner. After all, if the female you’re mating with is unlikely to get pregnant at the time, whatever resources are being invested into an ejaculate are correspondingly more likely to represent wasted effort; a case where the male would be better off investing those resources to things other than his loins. What this means is that – in addition to between-species differences of average investment in sperm/semen production – there might also exist within-individual differences in the amount of resources devoted to a given ejaculate, contingent on the context. This idea falls under the lovely-sounding name, the theory of ejaculate economics. Put into a sentence, it is metabolically costly to “buy” ejaculates, so males shouldn’t be expected to invest in them irrespective of their adaptive value.

A prediction derived from this idea, then, is that males might invest more in semen quality when the opportunity to mate with a fertile female is presented, relative to when that same female is not as likely to conceive. This very prediction happens to have been recently examined by Jeannerat et al (2017). Their sample for this research consisted of 16 adult male horses and two adult females, each of which had been living in a single-sex barn. Over the course of seven weeks, the females were brought into a new building (one at a time) and the males were brought in to ostensibly mate with them (also one at a time). The males would be exposed to the female’s feces on the ground for 15 seconds (to potentially help them detect pheromones, we are told), after which the males and females were held about 2 meters from each other for 30 seconds. Finally, the males were led to a dummy they could mount (which had also been scented with the feces). The semen sample from that mount was then collected from the dummy and the dummy refreshed for the next male.

This experiment was repeated several times, such that each stallion eventually provided semen after exposure to each mare two or three times. The crucial manipulation, however, involved the mares: each male had provided a semen sample for each mare once when she was ovulating (estrous) and two to three times when she was not (dioestrous). These samples were then compared against each other, yielding a within-subjects analysis of semen quality.

The result suggested that the stallions could – to some degree – accurately detect the female’s ovulatory status: when exposed to estrous mares, the stallions were somewhat quicker to achieve erections, mount the dummy, and to ejaculate, demonstrating a consistent pattern of arousal. When the semen samples themselves were examined, another interesting set of patterns emerged: relative to dioestrous mares, when the stallions were exposed to estrous mares they left behind larger volumes of semen (43.6 mL vs 46.8 mL) and more motile sperm (a greater percentage of active, moving sperm; about 59 vs 66%). Moreover, after 48 hours, the sperm samples obtained from the stallions exposed to estrous mares showed less of a decline of viability (66% to 65%) relative to those obtained from dioestrous exposure (64% to 61%). The estrous sperm also showed reduced membrane degradation, relative to the dioestrous samples. By contrast, sperm count and velocity did not significantly differ between conditions.

“So what it was with a plastic collection pouch? I still had sex”

While these differences appear slight in the absolute sense, they are nevertheless fascinating as they suggest males were capable of (rather quickly) manipulating the quality of the ejaculate they provided from intercourse, depending on the fertility status of their mate. Again, this was a within-subjects design, meaning the males are being compared against themselves to help control for individual differences. The same male seemed to invest somewhat less in an ejaculate when the corresponding probability of successful fertilization was low.

Though there are many other questions to think about (such as whether males might also make long-term adjustments to semen characteristics depending on context, or what the presence of other males might do, to name a few), one that no doubt pops into the minds of people reading this is whether other species – namely, humans – do something similar. While it is certainly possible, from the present results we clearly cannot say; we’re not horses. An important point to note is that this ability to adjust semen properties depends (in part) on the male’s ability to accurately detect female fertility status. To the extent human males have access to reliable cues regarding fertility status (beyond obvious ones, like pregnancy or menstruation), it seems at least plausible that this might hold true for us as well. Certainly an interesting matter worth examining further.   

References: Jeannerat, E., Janett, F., Sieme, H., Wedekind, C., & Burger, D. (2017). Quality of seminal fluids varies with type of stimulus at ejaculation. Scientific Reports. 7, DOI: 10.1038/srep44339

 

The Connection Between Economics and Promiscuity

When it comes to mating, humans are a rather flexible species. In attempting to make sense of this variation, a natural starting point for many researchers is to try and tackle what might be seen as the largest question: why are some people more inclined to promiscuity or monogamy than others? Though many answers can be given to that question, a vital step in building towards a plausible and useful explanation of the variance is to consider the matter of function (as it always is). That is, we want to be asking ourselves the question, “what adaptive problems might be solved by people adopting long- or short-term mating strategies?” By providing answers to this question we can, in turn, develop expectations for what kind of psychological mechanisms exist to help solve these problems, explanations for how they could solve them, and then go examine the data more effectively for evidence of their presence or absence.

It will help until the research process is automated, anyway

The current research I wanted to talk about today begins to answer the question of function by considering (among other things) the matter of resource acquisition. Specifically, women face greater obligate biological costs when it comes to pregnancy than men. Because of this, men tend to be the more eager sex when it comes to mating and are often willing to invest resources to gain favor with potential mates (i.e., men are willing to give up resources for sex). Now, if you’re a woman, receiving this investment is an adaptive benefit, as it can be helpful in ensuring the survival and well-being of both yourself and your offspring. The question then becomes, “how can women most efficiently extract these resources from men?” As far as women are concerned, the best answer – in an ideal world – is to extract the maximum amount of investment from the maximum amount of men.

However, men have their own interests too; while they might be willing to pay-to-play, as it were, the amount they’re willing to give up depends on what they’re getting in return. What men are looking for (metaphorically or literally speaking) is what women have: a guarantee of sharing genes with their offspring. In other words, men are looking for paternity certainty. Having sex with a woman a single time increases the odds of being the father of one of her children, but only by a small amount. As such, men should be expected to prefer extended sexual access over limited access. Paternity confidence can also be reduced if a woman is having sex with one or more other men at the same time. This leads us to expect that men adjust their willingness to invest in women upwards if that investment can help them obtain one or both of those valued outcomes.

This line of reasoning lead the researchers to develop the following hypothesis: as female economic dependence on male investment increases, so too should anti-promiscuity moralization. That is, men and women should both increase their moral condemnation of short-term sex when male investment is more valuable to women. For women, this expectation arises because promiscuity threatens paternity confidence, and so their engaging in mating with multiple males should make it more difficult for them to obtain substantial male investment. Moreover, other women engaging in short-term sex similarly makes it more difficult for even monogamous women to demand male investment, and so would be condemned for their behavior as well. Conversely, since men value paternity certainty, they too should condemn promiscuity to a greater degree when their investment is more valuable, as they are effectively in a better position to bargain for what they want.

In sum, the expectation in the present study was that as female economic dependence increases, men and women should become more opposed to promiscuous mating.

“Wanted: Looking for paternity certainty. Will pay in cash”

This was tested in two different ways: in the first study, 656 US residents answered questions about their perceptions of female economic dependence on male investment in their social network, as well as their attitudes about promiscuity and promiscuous people. The correlation between the measures ended up being r = .28, which is a good proof of concept, though not a tremendous relationship (which is perhaps to be expected, given that multiple factors likely impact attitudes towards promiscuity). When economic dependence was placed into a regression to predict this sexual moralization, controlling for age, sex, religiosity, and conservatism in the first step, it was found that female economic dependence accounted for approximately 2% of the remaining variance in the wrongness of promiscuity ratings. That’s not nothing, to be sure, but it’s not terribly substantial either.

In the second study, 4,626 participants from across the country answered these same basic questions, along with additional questions, like their (and their partner’s) personal income. Again, there was a small correlation (r = .23) between female economic dependence and wrongness of promiscuity judgments. Also again, when entered into a regression, as before, an additional 2% of the variance in these wrongness judgments was predicted by economic dependence measures. However, this effect became more substantial when the analysis was conducted at the level of the states, rather than at the level of individuals. At the state level, the correlation between female economic dependence and attitudes towards promiscuity now rose to r = .66, with the dependence measure predicting 9% of the variance of promiscuity judgments in the regression with the other control factors.

Worth noting is that, though a women’s personal income was modestly predictive of her attitudes towards promiscuity, it was not as good of a predictor as her perception of the dependence of women she knows. There are two ways to explain this, though they are not mutually exclusive: first, it’s possible that women are adjusting their attitudes so as to avoid condemnation of others. If lots of women rely on this kind of investment, then she could be punished for being promiscuous even if it was in her personal interests. As such, she adopts anti-promiscuity attitudes as a way of avoiding punishment preemptively. The second explanation is that, given our social nature, our allies are important to us, and adjusting our moral attitudes so as to gain and maintain social support is also a viable strategy. It’s something of the other side of the same social support coin, and so both explanations can work together.

The dual-purpose marriage/friendship ring

Finally, I wanted to discuss a theoretical contradiction I find myself struggling to reconcile. Specifically, in the beginning of the paper, the authors mention that females will sometimes engage in promiscuous behavior in the service of obtaining resources from multiple males. A common example of this kind of behavior is prostitution, where a woman will engage in short-term intercourse with men in explicit exchange for money, though the strategy need not be that explicit or extreme. Rather than obtaining lots of investment from a single male, then, a viable female strategy should be to obtain several smaller investments from multiple males. Following this line of reasoning, then, we might end up predicting that female economic dependence on males might increase promiscuity and, accordingly, lower moral condemnation of it, at least in some scenarios.

If that were the case, the pattern of evidence we might predict is that, when female economic dependence is high, we should see attitudes towards promiscuity become more bi-modal, with some women more strongly disapproving of it while others become more strongly approving. As such, looking at the mean impact of these economic factors might be something of a wash (as they kind of were on the individual level). Instead, one might be interested in looking at the deviations from the mean instead, and see if those areas in which female economic dependence is the greatest show a larger standard deviation from the average moralization value than those in areas of lower dependence. Perhaps there are some theoretical reasons that this is implausible, but none are laid out in the paper.

References: Price, M., Pound, N., & Scott, I. (2014). Female economic dependence and the morality of promiscuity. Archives of Sexual Behavior, 43, 1289-1301.