European Human Behaviour and Evolution Association Conference 2013

Last week I attended EHBEA2013 in Amsterdam.  This was the eighth meeting of the association, the ninth will be held in Bristol.

EHBEA is not an exclusive evolutionary psychology organization but rather one that encourages contributions from evolutionary psychology, human behavioural ecology, cultural evolution, behavioural economics and other traditions.  The only stipulation is that the hypotheses are drawn from evolutionary theory.  This year's meeting conformed to this ambition (click on the EHBEA2013 link above for more details).

One thing that caught my imagination was work on public goods games (PGG). PGG work as follows:

(1) A group of people each have individual pots of money;
(2) They are asked to make a contribution to the common pot;
(3) When all contributions are made the pot is multiplied (the multiplier varies from experiment to experiment);
(4) The new amount in the common pot is divided equally between all the players.

A key thing to note is that players do not have to contribute to the common pot and most games are conducted anonymously.

Free-riding in this game is a rational strategy under neo-classical economic assumptions and also possible fitness maximizing assumptions of a certain sort. Make no contribution, but still yield a return and watch your money grow!  Given anonymity one might predict a zero contribution would be the normative response, but in fact this has been shown not to be the case time and time again.  People make 'generous' contributions that do fall off over repeated plays but still remain well above zero.  Of course, there are some free-riders, but it is not a majority strategy.

This paper by Simon Gachter, one of the keynote speakers this year, takes you through some interesting details.  One detail that he discussed at the meeting was the effect of social contact.  If players get to meet, with no proper interaction, for 30 seconds or so just before they go to their anonymized computer terminals to play, the average contribution goes up and remains higher than normal, in spite of a standard decline in contribution over repeated plays.  This social meeting is minimal, with no conversation or any information exchanged.  They just see each other for a short spell.

This is of interest to evolutionary theorists because cooperation of any sort is a hard thing to stablize in populations.  Check this paper out for a clear-sighted view on the field.  It might also be interesting to those managing people to solve a collective action problem.  Our department is one such space with parallel iterated collective action games ongoing.  Whether or not they are all technically public goods games is something to ponder, as is the possibility of rendering them so, should they fail to conform.

I had some other thoughts about the trip which can be found here.

Tom Dickins