Mate Choices Can Be Complex, But Are They Oedipal Complex?

Theory is arguably the most important part of research. A good theory helps researchers formulate better research questions as well as understand the results that their research projects end up producing.I’ve said this so often that expressing the idea is closer to a reflex than a thought at this point. Unfortunately, “theories” in psychology – if we can even call them theories – are frequently of poor quality, if not altogether absent from research, leading to similarly poorly formulated projects and explanations. Evolutionary theory offers an escape from this theoretically shallowness, and it’s the major reason the field appeals to me. I find myself somewhat disappointed, then, to see a new paper published in Evolutionary Psychology that appears to be, well, atheoretical.

No, I’m not mad; I’m just disappointed…

The paper was ostensibly looking at whether or not human children sexually imprint on the facial traits of their opposite sex parent, or, more specifically (for those of you that don’t know about imprinting):

Positive sexual imprinting has been defined as a sexual preference for individuals possessing the characteristics of one’s parents… It is said to be a result of acquiring sexual preferences via exposure to the parental phenotype during a sensitive period in early childhood.

The first sentence of that definition seems to me to be unnecessary. One could have preferences for characteristics that one’s parents also happen to possess without those preferences being the result of any developmental mechanism that uses parental phenotype as its input. So I’d recommend using the second part of the definition, which seems fine, as far as describing sexual imprinting on parents goes. As the definition suggests, such a mechanism would require (1) a specified developmental window during which the imprinting takes place (i.e. the preferences would not be acquired prior to or after that time, and would be relatively resistant to change afterwards) and (2)  that mechanism to be specifically focused on parental features.

So how did Marcinkowska & Rantala (2012) go about testing this hypothesis? Seventy subjects, their sexual partner, and their opposite sex parent (totaling 210 people) were each photographed from straight ahead and in profile. These subjects were also asked to report about their upbringing as a child. Next, a new group of subjects were presented with an array of pictures: on one side of the array was a picture of one of the opposite sex parents; on the other side there were four pictures, one of which was the partner of that parent’s child and three of which were controls. The new subjects were asked to rate how similar the picture of the parent was to the pictures of the people on the other side of the display.

The results showed that the group of independent raters felt that a man’s mother resembled slightly more closely his later partner than the controls did. The results also showed that the same raters did not feel that a woman’s father more closely resembled her later partner than the control did. Neither of these findings were in any way related to the self-reports that subjects had delivered about their upbringing either. If you’ve been following along so far, you might be curious as to what these results have to do with a sexual imprinting hypothesis. As far as I can tell, the answer is a resounding, “nothing”.

Discussion: Never mind

Let’s consider what these results don’t tell us: they certainly don’t speak to the matter of preferences. As Marcinkowska & Rantala (2012) note, actual mating preferences can be constrained by other factors. Everyone in the population might wish to monopolize the matings of a series of beautiful others, but if those beautiful others have different plans, that desire will not be fulfilled. Since the initial definition of imprinting specifically referenced preferences – not actual choices – the findings would have very little relevance to the matter of imprinting no matter how the data fell out. It’s worse than that, however: this study didn’t even attempt to look for any developmental window either. The authors seemed to just assume it existed without any demonstration that it actually does.

What’s particularly peculiar about this oversight is that, in the discussion, the authors note they did not look at any adoptive families. This suggests that the authors at least realized there were ways of testing to see if this developmental window even exists, but didn’t seem to bother running the required tests. A better test – one that might suggest such a developmental window exists – would be to test preferences of adoptive or step-children towards the features of their biological and adoptive/step-parents. If the imprinting hypothesis was true, you would expect that adoptive/step-children would prefer the characteristics of their adoptive/step-parents, not their biological ones. Further, this research could be run with respect to the time at which the new parent came into the picture (and the old one left). If there is a critical developmental window, you should only expect to see this effect when the new parent entered into the equation at a certain age; not before or beyond that point.

The problems don’t even end there, however. As I mentioned previously, this paper appears atheoretical in nature, in that the authors give absolutely no reason as to why one would expect to find a sexual imprinting mechanism in the first place, why it would operate in early childhood, let alone why that mechanism would be inclined to imprint on one’s close, biological kin. What the precise fitness benefits to such a mechanism would be are entirely unclear to me, though, at the very least, I could see it carrying fitness costs in that it might heighten the probability of incest taking place. Further, if this mechanism is presumably,active in all members of our species, and each person is looking to mate with someone who resembles their opposite sex parent, it would seem that such a preference might actively disincline people from having what would be otherwise adaptive matings. Lacking any theoretical explanation for any of this, the purpose of the research seems very confusing.

On the plus side, you can still add it to your resume, and we all know how important publications are.

All that said, even if research did find that people tended to be attracted to the traits of their opposite sex parent, such a finding could, in principle, be explained by sexual selection. Offspring inherent genes from their parents that both contributed to their parent’s phenotype as well as genes that contributed to their parent’s psychological preferences. If preferences were not similarly inherited, sexual selection would be impossible and ornaments like the peacock’s tail could never have come into existence. So, presuming your parents found each other at least attractive enough to get together and mate, you could expect their offspring to resemble them both physically and psychologically to some extent. When those offspring are then making their own mate choices, you might then expect them to make a similar set of choices (all else being equal, of course).

What can be said for the study is that it’s a great example of how not to do research. Don’t just assume the effect you’re looking to study exists; demonstrate that it does. Don’t assume that it works in a particular way in the event that it actually exists either. Most importantly, don’t formulate your research project in absence of a clearly stated theory that explains why such an effect would exist and, further, why it would work the way you expect it might. You should also try and rule out alternative explanations for whatever findings you’re expecting. Without good theory, the quality of your research will likely suffer, and suffer badly.

 References: Marcinkowska, U.M., & Rantala, M.J. (2012). Sexual Imprinting on Facial Traits of Opposite-Sex Parents in Humans. Evolutionary Psychology, 10, 621-630

Intentional Or Not, Incest Is Still Gross (And Wrong)

For a moment, let’s try to imagine a world that isn’t our own. In this world, the intentions behind an act are completely disregarded when it comes to judging that act morally; the only thing that matters is the outcome. In this world, a man who trips and falls down the stairs, accidentally hitting another man on the way down, is just as wrong as the man who walks up to another and angrily punches him right in the face. In another case, a sniper tries to assassinate the president of the country, but since he misses by an inch no one seems to care.

Such a world would be a strange place to us, yet our sense of disgust seems to resemble the psychology of that world to some degree. While intent doesn’t stop mattering altogether when it comes to disgust, it would seem to matter in a different way than is typically envisioned when it comes to the domain of physical harm.

Sure, it may look disgusting – morally or otherwise – but who doesn’t love Red Velvet?

A recent paper by Young & Saxe (2011) set out to examine the role that intentions placed in the contexts of a more physical harm – poisoning – relative to their role in contexts that elicited disgust – the ever popular case of sibling incest. Subjects read stories in which incest was committed or a friend served another friend peanuts despite knowing about their friend’s peanut allergy; for these stories there was a bad intent and a bad outcome. When both acts were committed intentionally, harm tended to be rated as slightly more morally wrong than incest (6.68 vs 6.03, out of 7). However, the story changed when both acts were committed by accident – when there was still a bad outcome, but only neutral intentions. While the harm condition was now rated as not very wrong, the incest condition was still rated as fairly wrong (2.05 vs 4.24, out of 7).

Another study basically replicated the results of the first, but with one addition: there was now an attempt condition in which an actor intends to commit an act (either harm someone or commit incest), but fails to do so. While the intentional condition (bad intent and bad outcome) was rated as the worst for both incest and harm, and the accidental condition (neutral intent and bad outcome) saw incest rated as worse than harm, the attempt condition showed a different pattern of results: while attempted harm was rated to be just as bad as intentional harm (6.0 and 6.5, respectively), attempted incest was rated more leniently than intentional incest (4.2 and 6.4). In other words, moral judgments of incest were more outcome dependent, relative to moral judgments of harm.

One final study on the topic looked at two different kinds of failed attempts concerning incest and harm: the ‘true belief but failed act’ and the ‘false belief but completed act’. The former involved (in the case of incest) two siblings correctly believe they’re siblings and attempt to engage in intercourse but are interrupted before they complete the act. The latter involved two people who incorrectly believe they’re siblings and actually engage in intercourse. The harm contexts were again outcome independent: whether the harm was completed or not didn’t matter. However, the incest contexts told a different story: the ‘true belief but failed act’ condition  was rated as being more immoral than the ‘false belief but completed act’ condition (5.65 vs 4.2). This means subjects were likely rating the act relative to how close it approximated actual incest, and the subjects apparently felt an unconsummated attempt at real incest looked more like incest than a consummated act where the two were just mistaken about their being siblings.

And I think we can all relate to that kind of disappointment…

A further two studies in the paper sought to examine two potential ways to account for this effect. In one case, subjects rated the two stories with respect to how emotionally upsetting they were, how much control over the situation and knowledge of the situation the actors had, and the extent to which the agents were acting intentionally. In no case were there any significant differences, whether concerning disgust or harm, or whether the act was intentional or accidental. The subjects seemed to be assessing the two stories in the same fashion. The second study sought to examine whether subjects were using moral judgments to express the disgust they felt about the story, rather than actually judging the act to be immoral. However, while subjects rated intentional incest as worse than accidental incest, they rated both to be equally as disgusting. Accordingly, it seems unlikely that people were simply using the morality scale as a proxy for their disgust.

It is my great displeasure to have to make this criticism of a paper again, but here goes: while the results are interesting,Young & Saxe (2012) really could have used some theory in this paper. Here’s their stated rationale for the current research:

Our hypothesis was initially motivated by an observation: in at least some cultures, people who commit purity violations accidentally or unknowingly are nevertheless considered impure and immoral.

Observing something is all well and good, but to research it, one should – in my opinion – have a better reason for doing so than just a hunch you’ll see an effect. The closest the authors come to a reasonable explanation of their findings – rather than just a restatement of them – is found in the discussion section, and it takes the form of a single sentence, again feeling like an afterthought, rather than a guiding principle:

…[R]ules against incest and taboo foods may have developed as a means for individuals to protect themselves, for their own good, from possible contamination.

Unfortunately, none of their research really speaks to that possibility. I’d like to quickly expand on that hypothesis, and then talk about a possible study that could have been done to examine it.

Finding an act disgusting is a legitimate reason to not engage it yourself. While that would explain why someone might not want to have sex with their parents or siblings, it would not explain why one would judge others as morally wrong for doing so. For instance, I might not feel inclined to eat insects, but I wouldn’t want someone else punished because they enjoyed doing so. However, within the realm of disgust, the threat of contamination looms large, and pathogens aren’t terribly picky about who they infect. If someone else does something that leads to their becoming infected, they are now a potential infection risk to anyone they interact with (depending on how the pathogen spreads). Accordingly, it’s often not enough to simply avoid engaging in a behavior yourself; one needs to avoid interacting with other infected agents as well. One way to successfully deter people from interacting with you just happens to be aggressive behavior. This might, to some extent, explain the link between disgust and moral judgments. It would also help explain the result that disgust judgments are outcome dependent: even if you didn’t intend to become infected with a pathogen, once you are infected you pose the same risk as someone who was infected more intentionally. So how might we go about testing such an idea?

One quick trip to the bookstore later…

While you can’t exactly assign people to a ‘commit incest’ condition, you could have confederates that do other potentially disgusting things, either intentionally or accidentally, or attempt to do them, but fail (in both cases of the false or true beliefs). Once the confederate does something ostensibly disgusting, you assign them a partner in one of two conditions: interacting at a distance, or interacting in close proximity. After all, if avoiding contamination is the goal, physical distance should have a similar effect, regardless of how it’s achieved. From there, you could compare the willingness of subjects to cooperate or punish the confederate, and check the effect of proximity on behavior. Presumably, if this account is correct, you’d expect people to behave less cooperatively and more selfishly when the confederate had successfully done something disgusting, but this effect would be somewhat moderated by physical distance: the closer the target of disgust is, the more aggressive we’d expect subjects to be.

One final point: the typical reaction to incest – that it’s morally wrong – is likely a byproduct of the disgust system, in this account. Incestuous acts are, to the best of my knowledge, no more likely to spread disease than non-incestuous intercourse. That people tend to find them personally rather disgusting might result in their being hooked onto the moral modules by proxy. So long as morally condemning those who engaged in acts like incest didn’t carry any reliable fitness costs, such a connection would not have been selected against.

References: Young, L., & Saxe, R. (2011). When ignorance is no excuse: Different roles for intent across moral domains Cognition, 120 (2), 202-214 DOI: 10.1016/j.cognition.2011.04.005

Was Freud Right? Are You Sexually Attracted To Your Parents?

No, you probably are not.

Well, that was easy. Given that sexual reproduction evolved specifically to introduce some genetic diversity to future generations in order to remain ahead of the more quickly evolving parasites (Ridley, 1993), the suggestion that humans would also have some adaptations that predisposed them to breed with their immediate relatives seems misguided. Freud – I’m told – had suggested that children really did want to have sex with their parents, and it was only through imposition of a cultural taboo against incest that such drives were thwarted. It’s just one of the many things he was wrong about.

“I don’t always talk about your mother, but when I do… wait, never mind; I do always talk about your mother”

Might there have been something to that notion of Freud’s though? No. Go read the introduction again if you’re still confused on that point. However, there is at least one recent research paper in which the authors suggest that there may in fact be some forces at work that generate sexual attraction to closely related family members that a societal taboo is needed to stand in the way of. In a series of three experiments, Fraley & Marks (2010) attempt to demonstrate that possibility.

In the first experiment, subjects were either primed with a picture of their opposite sex parent, or were controls that were unrelated to that parent. Subjects were then asked to rate a few pictures of opposite sex strangers for their sexual attractiveness. The results showed a slight tendency for those who saw a picture of their parent to rate others as more attractive (a difference of about 0.2 on a scale of 1 to 7). The second study went a bit deeper. This time, participants had their own face morphed from 0 to 40% with those of opposite sex strangers and rated the new photos for attractiveness; the control group rated the same pictures, but were not the person being morphed into the photos. The results showed a similar pattern: there was a slight tendency for people who’s faces had been morphed into the photos to rate them as more attractive (a difference of about a 0.4 on the same scale), relative to the controls. Finally, in the third experiment, the researchers lied to the participants about how much of their face had been morphed into the photos and mentioning the study was examining incestuous tendencies. This time, the effect reversed; participants rated the pictures with self-morphs as being slightly less attractive, relative to controls.

So where does that leave us?

Hiding in our closest, aka “The Shame Cave”?

Are we to admit Freud was onto something? No, and stop asking that silly question. Since I’m a big fan of theory, naturally my first question was: what was theory guiding this research? According to Fraley & Marks, the following findings need an explanation: (1) people tend to enter into relationships with others who are similar physically on a variety of traits, (2) that people tend to enter into relationships with those who live around them and are familiar, and (3) people find those who they are exposed to more frequently more attractive than those they’re exposed to less frequently. However, those three findings do not a theory make; they need a theory to explain them, preferably one that doesn’t cut again incest avoidance. Here’s a simple and probable one that accounts for at least part of the picture here: sexual selection.

Take any species; since I like peacocks, I’ll use them. When mating season roles around, the peacocks flaunt for the peahens, they have steamy bird sex, and soon after a new generation of birds are hatched into this world. The peacocks will inherit their father’s sexy tails, and the peahens will inherit something else: their mother’s preferences for those sexy tails. If those sexual preferences weren’t inherited, mating in the next generation would be random with respect to the tails. Since it isn’t, we can safely assume that, to at least some extent, the preferences are hereditary.

Just like the inter-generational preference for hunting equipment. I’m a shotgun man, myself.

So let’s return to the facts in need of an explanation. Picture your mother and father having sex to conceive you – make Freud proud. Whatever physical traits your parents had will be passed onto you. Additionally, whatever preferences your parents had for those traits that attracted them to each other will be passed on as well. That would seem to be able to explain (1) and the results of the photo manipulation study fairly well. By morphing in your own traits to the picture to some degree, you’re morphing in those same traits that you’re going to tend to have a preference towards. The result? You find those pictures slightly more attractive.

How about the first experiment that primed pictures of the parents? It seems at least plausible that if one truly found their opposite sex parent attractive, ratings of strangers would go down by comparison, not up. Concluding that one found strangers more sexually appealing because of that sexual aversion to their parents would be just as consistent with the data; at the very least, it can’t be ruled out by the results found here. As for the third experiment, admitting a sexual attraction to one’s own family can be quite socially damning, so it hardly seems surprising that people would avoid doing so.

“You look just like my sister and that is so hot! Would you mind wearing her clothes?”

Now I want to look at how the authors explain their results. Fraley & Marks (2010) suggest the following:

…the mechanisms that promote familiarity, bonding, and attraction are most likely to operate on inputs experienced in the early family environment. For example, if sexual imprinting really takes place in humans, then one’s early interactions with primary attachment figures can play an influential role in shaping the “ideal” for what kinds of people one will find attractive…

A tempting suggestion for some, no doubt, until one asks some perfectly relevant questions, like: why would the sexual imprinting take place during early interactions in childhood? Why would the stimulus that the imprinting responds to be the caregivers in the house (especially them, given the costs of inbreeding), as opposed to the environment outside the family? Combining the two questions gives us the following: Why would anyone suppose evolution had designed our psychology to become sexually attracted (in the long term) to the physical traits of our close genetic relatives at a time that we are pre-reproductive? Frankly, I can’t think of a reason we would expect that to happen, and one isn’t suggested in the paper.

On the same token, Fraley & Marks (2010) go on to suggest that the aversion to incest is simply a matter of habituation – as opposed to the Westermarck effect – but again offer no reason as to why habituation would have this particular effect. At the same time, habituation would also seem to make people more attractive the more familiar they were, according to the author’s interpretation of their work, and while Fraley & Marks (2010) note this contradiction, they don’t do a good job of explaining it away. They try to draw on some kind of distinction between the conscious and unconscious recognition of the familiar, but I don’t think they make a case for it.

On the whole, that is a very unsatisfying explanation, especially compared to other models of incest aversion. Point: Westermark. Freud is still wrong.

References: Fraley, R.C. & Marks, M.J. (2010). Westermarck, Freud, and the incest taboo: does familial resemblance activate sexual attraction? Personality and Social Psychology Bulletin, 36, 1202-1212

Ridley, M. (1993). The Red Queen: Sex and the Evolution of Human Nature. Harper: New York.