Information combination in two-step decisions.

Abstract

Research examined information combination in both choice and pre-choice (screening) phases of decision making. Three experiments required subjects to review a set of multiattributed options for a possible purchase. Each option had either high or low expected probability of availability, and a set number of positive or negative attributes. In the first experiment, subjects were asked to indicate their preferred choices. Analysis showed that the majority of subjects multiplicatively combined the probability of option availability with other option attributes, as predicted by expected utility theory. In the second experiment, subjects were asked to eliminate unacceptable options, but not choose. Analysis showed that the majority of subjects additively combined information on negative option attributes (violations) with low probability of option availability, as predicted by image theory. The third experiment showed that when choice immediately followed screening, 28% of the subjects used multiplicative information combination to make the choice, 28% used additive combination, and both types of combination were equally dominant in the remaining 44% of the subjects.