Why are the batteries in the microwave?: Use of semantic information under uncertainty in a search task

Abstract

A major problem in human cognition is to understand how newly-acquired information combines with long-standing beliefs about the environment to make decisions and plan behaviors. While considerable attention has been given to studying how beliefs derived from past experience are updated with new evidence, less is known about how new evidence can modify expectations derived from long-standing beliefs about the environment. Resistance to modifying such beliefs may be a significant source of suboptimal decision-making. The present study examined the role of long-standing semantic beliefs during active search through visual scenes. Target locations were either congruent with scene semantics (semantic priors), incongruent with what would be expected from scene semantics (inverted priors), or random. The incongruent condition requires that semantic beliefs be preserved, but used in unconventional ways. The ability to adjust expectations to the task environment was evaluated by determining the likelihood of search decisions under three different Bayesian models, one based on semantic priors, another on inverted priors, and a third on a uniform prior. Half of the 10 subjects were able to invert semantic priors over repeated experimental sessions, with limited success, but the remaining subjects either failed to invert semantic priors, or searched at random. These results indicate that structural modification of semantic beliefs derived from knowledge of scenes is possible when the modification is systematic and beneficial, but that strong beliefs are resistant to structural modification, suggesting there are limits on our ability to modify the use of long-established knowledge structures to accomplish task goals.