Automatic activation of attribute knowledge in heuristic inference from memory

In memory-based decision making, people often rely on simple heuristics such as take-the-best (TTB; Gigerenzer & Goldstein, Psychological Review, 103, 650-669, 1996), which processes information about the alternatives sequentially and stops processing as soon as a decision can be made. In this article, we examine the memory processes associated with TTB-in particular, to what degree the selective memory retrieval of relevant information required by TTB is accompanied by automatic activation of associated but irrelevant information. To address this question, we studied the fan effect (Anderson, Cognitive Psychology, 6, 451-474, 1974), which is assumed to arise from automatic spread of activation, in inferences from memory. Participants were instructed to use TTB when making decisions about objects on the basis of previously memorized attribute information. Both the number of attributes required by TTB and the number of attributes associated with an object (i. e., fan level) were manipulated. As it turned out, response times and the correct execution of TTB were a function not only of the number of required attributes, but also of the number of associated attributes. This suggests that information that TTB "ignores" is nevertheless activated in memory.