Presentation on evolutionary game theory and cognition

Last week Julian sent me an encouraging email:

did you know that you come up first in google for a search “evolutionary theory mcgill university”? You beat all the profs!

The specific link he was talking about was to my slides from the first time I gave a guest lecture for Tom’s Cognitive Science course in 2009. Today, I gave a similar lecture again; my 3rd year in a row giving a guest lecture for PSYC532. The slides are available here.

I am very happy Tom invited me. It is always fun to share my passion for EGT with students, and I like motivating the connections to cognition. As if often the case, some of the questions during the presentation got me thinking. A particular question I enjoyed, was along the lines of:

If humanitarians cooperate with everyone, and ethnocentrics only cooperate with in-group, then how can we have lower levels of cooperation when the world is dominated by humanitarians?

This was in reference to a result I presented in [Kaz10] about the decrease in cooperative interactions as the cognitive costs of ethnocentrism increases. In particular, even though ethnocentrics are replaced by humanitarians in the population, we don’t see an increase in the proportion of cooperative interactions. In fact, it triggers a decrease in the proportion of cooperative interactions.

I started with my usual answer of the humanitarians allowing more selfish agents to survive, but then realized a second important factor. When the ethnocentric agents are a minority, they no longer form giant same-tag clusters, and are thus much more likely to be defecting (since they are meeting agents of other tags) than cooperating. Thus, the sizable minority of ethnocentrics tend to defect and decrease the proportion of cooperation when living among a majority of humanitarians. On the other hand, when the ethnocentrics are in the majority they are in same-tag clumps and thus tend to cooperate. Of course, I should more closely analyze the simulation data to test this story.

Another attentive student caught a mistake on slide 14 (page 19 of pdf). I have left it for consistency, but hopefully other attentive readers will also notice it. Thank you for being sharp and catching an error I’ve had in my slides for 2 or 3 years now!

To all the students that listened and asked great questions: thank you! If you have any more queries please ask them in the comments. To everyone: how often do you get new insights from the questions you receive during your presentations?

References

[Kaz10] Kaznatcheev, A. (2010) “The cognitive cost of ethnocentrism.” Proceedings of the 32nd annual conference of the cognitive science society. [pdf]