Models of social preferences explain departures from pure self-interest as a
consequence of either outcome-based or intention-based other-regarding motives.
Various experimental studies lend support to the conclusion that subjects behave as
if they conditioned their behaviour on the perceived intentions of others. We
present a new experiment that explores this as if clause by making the ability to
detect intentions a treatment variable. We compare normally developing children
with autistic children – typically unable to perceive intentions – and find differences
consistent with the hypothesis that behaviour responds to intentions, especially if
unkind.