They come to play: supply effects in an economic experiment

Our experiment challenges the standard, social preference, interpretation of choices in the double blind dictator game played in the lab without any context. We present treatments formulated to minimize the social preference reasons to give and, despite this, the allocations are identical to our replication of the standard double blind game, implying that altruism might be the wrong interpretation of giving. Instead, we hypothesize that giving might be driven by participants coming to the lab ready ‘to play’. The fact that there are strong correlations between participant responses to an attention deficit, hyperactivity disorder questionnaire and both the rate and level of giving provides direct sup-port for the hypothesis that lab participants impulsively give money away. However, we also show that having players earn their endow-ments attenuates the bias. KEY WORDS • demand effect • dictator game • experiment • impulsivity • social preferenc