Att människor i viss mån har sociala preferenser och bryr sig om andra än sig själva har visats i ett antal experiment, som emellertid har kritiserats för att vara just experiment. Tänk om det är så att personer som deltar i experiment anpassar sig och beter sig som de tror att forskaren vill att de ska bete sig? I så fall blir resultaten missvisande. Sådana farhågor har bl.a. uttrycks av John List och Steven Levitt. En ny studie, ”Can We Infer Social Preferences from the Lab? Evidence from the Trust Game”, antyder att deras oro kan stillas en smula:

In order to test whether individuals who are reciprocal in the real-world are also reciprocal in the lab, we compare the MBA students’ donation behavior to a measure of reciprocity obtained in the lab: their behavior as the responder in the Berg et al. (1995) trust game. In this game, the amount returned by the responder is a measure of her other-regarding preferences. To address any concern about a potential experimenter effect, we measure each subject’s sensitivity to social pressure via the Crowne-Marlowe (1960) social desirability scale. Social desirability is commonly thought of as an individual’s tendency to project favorable images of herself during social interaction, which allows us to control for the influence of social pressure or reputational concerns.

We find that responder behavior in the trust game predicts the amount donated to the university. A one standard deviation increase in the fraction of the amount returned to the sender by the responder increases the amount of donation by $31, equal to 31% of the average amount donated. This effect is robust to controlling for wealth and other demographic characteristics.

Interestingly, the amount returned by the responder in the trust game is not correlated with the social desirability scale, whereas the amount donated to the university is. This finding indicates that social pressure has a larger effect in the field than in the lab. As a result, this evidence suggests that, at least in our case, reciprocity is better measured in the lab than the field.

Fascinerande, på åtminstone två sätt:

1. Studien visar att laboratorieexperiment förmår generera bra mått på verkliga sociala preferenser — och att sådana preferenser är en realitet.
2. Deltagarna var MBAs från University of Chicago, en bastion för homo economicus-modellen. Även dessa beter sig alltså prosocialt, vilket inte minst är intressant mot bakgrund av diskussionen om huruvida nationalekonomin drar till sig eller skapar egoistiska människor.