Adjusting the Spanner: Testing an Evidence Accumulation Model of Decision Making

An experiment examined two aspects of performance in a multi-attribute inference task: i) the effect of stimulus presentation format (image or text) on the adoption of decision strategies; and ii) the ability of an evidence accumulation model, which unifies take-the-best (TTB) and rational (RAT) strategies, to explain participants’ judgments. Presentation format had no significant effect on strategy adoption at a group level. Individual level analysis revealed large intraparticipant consistency, including some participants who consistently changed the amount of evidence considered for a decision as a function of format, but wide inter-participant differences. A unified model captured these individual differences and was preferred to the TTB or RAT models on the basis of the minimum description length model selection criterion.