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 (summary; study) 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.

 

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

 

4. Mirror neurons 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 in the ~20 years since that original finding, 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. A neat article about the genetics or non-genetics of creativity, from Maria Konnikova.

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