brain science roundup, vol II

1. An old idea in evolutionary psychology is that symmetrical faces are more attractive. Why? The chain of logic is: symmetry indicates good health, good health indicates “good” genes, and “good” genes are desirable in partners. So, because we’re all just here to procreate with the best-gened person we can get to sleep with us, facial symmetry is attractive (that description might be too on the nose). The link between health and facial symmetry has been studied for better than two decades, but the evidence is underwhelming: a meta-analysis shows only a small positive effect linking health markers and facial symmetry. (Though, regardless of its actual link to health, people do judge symmetrical faces as healthier than less symmetrical faces.)

A new study (summarystudy) uses a sample of more than 4000 Englandites (Englanders? Englishmen? English?), and found no correlation between measures of facial symmetry and markers of childhood health:

we found no evidence of associations between facial FA and longitudinal health measures, which suggests that although gross facial asymmetries may be associated with specific pathological processes and injuries, subtle variations in facial symmetry (i.e. FA) are not associated with variations in general health during childhood.

So facial symmetry in general may not be a proxy for a health. Not a banner day for evolutionary psychology. It’s also worth noting that we may not always find symmetry attractive in the first place: one study found that symmetry is only a factor in the attractiveness of male, but not female, faces.

2. Humans automatically and rapidly make judgments about people based on their faces—everything from gender to attractiveness to trustworthiness to competence. Those judgments can be made with just a 1/10 of a second glance at a face, and are remarkably static—meaning a snap judgment is unlikely to change even if you see the face for a second or two and have more time to assess it. And not only are those judgments made quickly, they matter: first impressions of “competence” of faces has predicted, at above chance levels, the outcomes of congressional elections, even when no other information was available (see Todorov et al., 2005).

The implicit assumption of all this work on impressions is that those first impressions are based on unchanging physical features of each individual face. All cliches about the word “assume” hold true: a recent study finds that different pictures of the same face(e.g., from different angles) can lead to wildly divergent first impressions (summary;article). In fact,

there was just as much variability in trait ratings based on different photos of the same individual as there was in trait ratings across photos of different individuals.

In other words, different angles of the same person can produce responses as varied as pictures of different people altogether. Here’s a reliable “first impression” for interesting (if not “good”) research studies: they manage to be both surprising and completely predictable. Which this study is—certainly it raises questions about both what our social media avatars impress upon people looking at them, and more disconcertingly, whether those first impressions are malleable. I’m definitely rethinking the whole “Chevy Chase with a broken noise and crooked bowtie as avatar” thing.

3. Soccer goalkeepers can induce a visual illusion in the shooters, and help to gain themselves a slight edge.

4. Mirror neurons are coming up on twenty years old. Simply put, they are neurons in the motor cortex of monkeys (and humans) that in addition to firing when a monkey performs a particular action (as one would expect from motor cortical neurons), also fire when the monkey watches someone else perform the action. From that ounce of finding comes multiple pounds of speculation, and mirror neurons have become a sort of go-to touchstone for popular science books, which seize on mirror neurons as the essence of empathy and understanding the intentions of others and—therefore—what makes humans “human”. Neuroscientist VS Ramachandran calls them the “neurons that shaped civilization”, and a recent book title proclaims that mirror neurons will save your life (how? I do not know).

So, yeah, mirror neurons are probably oversold, it’s just not clear by how much. Cognitive scientist Gregory Hickock lays out in a short blog post (based on his recent book, The Myth of Mirror Neurons) an interesting, if much more mundane, explanation for the original mirror neuron finding. Rather than being some kind of “innate” empathy centers, he says, what if mirror neurons don’t occur in macaque monkeys unless they are trained in the laboratory? That wouldn’t mean mirror neurons don’t exist—there’s compelling evidence that part of autism spectrum disorder may have to do with problems in mirror neurons—but it certainly makes them less of a neuroscientific panacea, and probably makes a lot of bold, overzealous claims about them look foolish. See here for a good in-depth article on mirror neurons, and here for a real deep dive.

5. neat article about the genetics or non-genetics of creativity, from Maria Konnikova.

brain science roundup, vol I

A roundup of recent findings and articles—mostly brain-related—that I found intriguing.

1. The gambler’s fallacy is the belief that random events “balance out”, like thinking a coin that came up heads five times in a row is due for tails or that George Lucas is due for a good movie. New work suggests soccer goalies fall victim to that belief when trying to save penalty kicks (summaryarticle):

…the goalkeeper must guess the likely direction of the kick, and dive in anticipation, if they are to have a chance of saving the shot. …Following repeated kicks in the same direction, goalkeepers became increasingly likely to dive in the opposite direction on the next kick.

Humans are pattern-seekers, and we’re bad both at perceiving and generating randomness, so it’s not surprising that goalies would have this bias. The more surprising thing is that the shooters are able kick to random locations—they don’t have the same bias. But that’s not a universal: TJ Oshie is hockey shootout savant who excels precisely because he’s able to avoid tendencies and preferences in his shots. I wonder if the ability to “generate” randomness is a skill on which people differ, and if so, can we train people to get better at it?

2. I wrote a few months ago about how anti-discrimination policies at institutions can have the ironic or paradoxical effect of making white people less likely to “see” events as being discriminatory. A recent study (summaryarticle) finds that white participants shown sets of mugshots with greater proportions of black individuals are more likely to later support punitive sentencing policies:

we found that, ironically, exposure to extreme racial disparities may make the public less, and not more, responsive to attempts to lessen the severity of policies that help maintain those disparities.”

Pointing out discriminatory outcomes may not just be an ineffective way to reduce prejudice and discrimination, but actually a counterproductive one. Humans are clannish, and while that tribalism is often subconscious, it’s also automatic. If simply telling people further retrenches that tribalism, then perhaps the best question is simply this: what are the circumstances or situations in which it’s possible to tamp down or ignore those subconscious “lizard brain” pings of xenophobia or sexism or outgroup hatred? Can they be ignored?

3. There’s a well-supported theory that leaded gas increased global lead exposure and caused increased crime in the 1970s onward, owing to neurological deficits from lead poisoning (specifically in impulse control). A new report shows that mice whose mothers were exposed to even low levels of lead have more body fat and less insulin production than their no-lead counterparts, suggesting a role of environmental lead in weight/metabolism issues (summaryarticle).

Perinatal Pb exposure at blood lead levels between 4.1 µg/dL and 32 µg/dL is associated with increased food intake, body weight, total body fat, energy expenditure, activity, and insulin response in mice.

It’s a little surprising that lead could be linked not just to impaired cognitive abilities, but also impaired metabolism issues as well. But it’s intriguing because it suggests that lead could be one of the chemical causes for increasing obesity rates, which are going up not just in humans, but also in animals—suggesting some kind of environmental cause. I strongly recommend this recap of that phenomenon, which includes a description of a theory that capitalism underlies rising obesity rates (is there anything capitalism can’t do?).

 Studies that throw two different groups of people (men and women, liberals and conservatives) in a brain scanner and look for anatomical differences are like pop-science catnip. Neuroskeptic is skeptical of a study showing brain differences between sciences and humanities scholars.

Specifically, the scientists had more grey matter in the medial prefrontal cortex (p=0.035), but their humanist counterparts had a higher white matter density around the right hippocampus (p=0.018). On average.

The authors suggest that these brain regions are associated with autism—essentially arguing that from an anatomical perspective, scientists are all on the autism spectrum. Studies like these, though, often end up providing each “side” with “hard” evidence (the seductive allure of brain pictures) of the other’s innate defect. But it is not a shocking revelation that two groups that act differently have different brains, is it? There might be no greater disconnect between the media play a study gets and its utility than this class of “group brain comparison” studies.

 Finally, some very good and strongly recommended science reporting: Maria Konnikova on the paradox of how even having nothing but good choices available can be anxiety-inducing (see my discussion of Barry Schwarz’s The Paradox of Choice for more); a depressing read on sexual harassment in the sciences; Olga Khazan on the possible uselessness of the “trolley problem”, a moral dilemma used in almost all research on moral psychology.