Computational behavior theory and cultural evolution

Category Archives: Uncategorized

Empirical support for openness-persuasiveness dynamics

A recent study by Aral & Walker provides support that the openness-persuasiveness dynamics we suggested a few years ago actually goes on in cultural evolution. In short, we had put forward mathematical and simulation models to support the notion that learning from others produces individuals that, over time, become more conservative (less likely to learn from others) and more persuasive (more likely to convince others of one’s own ideas). These predictions have been confirmed by Aral & Walker, who showed that older Facebook users are more difficult to convince do adopt a Facebook app than younger users, and yet are better at convincing others to adopt the app. Up to now, we only had indirect evidence about openness (older people score low on openness in personality tests), and no evidence on persuasion.

We have submitted a comment to the journal relating Aral & Walker’s intriguing findings to our theory. You can find a slightly extended version here, essentially with more references to relevant work.

Human Cognitive Uniqueness conference videos are online!

Watch them here!

Understanding Human Uniqueness: Full Program

The program for Understanding Human Uniqueness has been finalized and is available here. See the conference page or the invitation flyer for more details.

Cultural variation in face perception!

My cousin alerted me of this paper about the cross-cultural perception of facial expressions, by Rachel Jack and colleagues. The study uses an innovative method to uncover how we perceive facial expressions, and more specifically whether `Westerners’ (Europe, North America) and ‘East Asians’ (China, Japan, Korea, Mongolia, Thailand, Taiwan) use the same criteria.

The authors find several differences, such as that Westerners pay more attention to the lower part of the face, while East Asians to the eyes. Also, East Asians attach more significance to the immediate signs of emotion, while Westerners pay more attention to later parts of facial displays. While more work is neededd to understand the reasons for these differences (the authors have some ideas in their Discussion), the data show clear variation in how emotions are perceived (and, presumably, produced) across cultures. The implication is that our emotion recognition mechanism cannot be wholly innate, but it must be open to learning the specifics of each culture.

This conclusion agrees with the fact that other aspects of facial perception, such as the perception of attractiveness, may vary across cultures. Many years ago (on my timescale, it was 2002), some colleagues and I tried to figure out how much nature and how much nurture we should expect in the perception of attractiveness. We concluded, based on what we know about perceptual mechanisms and about the evolution of biological signals, that people’s criteria of attractiveness should be mostly learned, thus leaving space for cross-cultural variation also in this domain. The paper is here.

Method. In case your are still reading, the method employed to reconstruct the criteria of Westerners and East Asians is as follows (simplifying a bit). A computer software generates short (1.25 s) animation of faces by combining randomly selected “facial action units” (AUs), which represent how different muscles move parts of the face. These movies (lots of them) were rated by observers for intensity and quality (sadness, happiness, anger, etc.). The idea is that, although the movies show random combinations of AUs, statistical analysis of people’s responses allow the reconstruction of each AU’s role. For example, the analysis might pick up that expressions including AU 6 (raising the cheeks) are typically rated as happier than expressions without AU6.

New evidence for early learning of sexual preferences

We have recently posted on our sex research blog the results of our latest survey on sexual preferences. We surveyed sexual attraction to such traits as tattoos, eyeglasses, eye color, skin tone, stature, heir lenght, hair color, body type, long nails, painted nails, eyeglasses, tattoos, body hair, facial hair, armpit hair, and smoking. We found evidence that heterosexual individuals often prefer traits they have seen during their childhood in the parent of the other sex. That is, heterosexual males appear to prefer traits found in their mother, while heterosexual females trait found in their father.

A summary of this study and of previous ones on early learning of sexual prefernces is provided in Hanna Aronsson’s Ph.D. thesis introduction.