Stepping Stone: Identifying self-image concerns from motivated beliefs: Does it matter how and whom you ask?

Beliefs are increasingly recognised as an important driver of behaviour, but measuring beliefs is not straightforward. We design a giving experiment to compare beliefs using different elicitation mechanisms when motivated reasoning may be present. We propose a new means of identifying self-image concerns through beliefs about the behaviour of others. Consistent with a simple theoretical framework, we find evidence of self-image biases for non-donors when beliefs are not incentivised, while donors' beliefs are more accurate, irrespective of the incentive mechanism. Offering a binary incentive does not reduce non-donors' pessimism about others, however, a variation of the Becker-DeGroot-Marschak (BDM) procedure does appear to "debias" their beliefs. Our results also show that belief biases do not vary with the timing of belief elicitation.