Tales of the unexpected: Attentional awareness, goal relevance, and prior exposure to an unexpected change.

Abstract

We report an experiment where we examine whether an unexpected stimulus change that occurs whilst performing an engaging task is more likely to be noticed if it is relevant or irrelevant to the goal of that task. The goal was to count the number of times moving targets (white letters) hit the side of the frame on a computer screen but to ignore similarly moving distractors (black letters). We found that a highly goal- relevant change (i.e., a black distractor changing into a white target) was more likely to be noticed than a less-relevant change (a white target turning into a black distractor). However, people with high working memory were more likely to notice the goal- relevant change but less likely to notice the goal-irrelevant change. High working memory capacity appears to be associated with the more efficient strategy, which is to notice the change when it is goal-relevant but to inhibit it when it is not relevant to prevent the possibility of interference with the goal of the primary task. We then investigated whether previous exposure to an unexpected change influenced the likelihood that a different change (an unexpected red cross in a standard dynamic inattentional blindness task) would be noticed. We observed prior experience of a change reduced the incidence of Inattentional Blindness. These findings are discussed in terms of dual-route model of Inattentional blindness, in which the failure to notice the unexpected stimulus may result from a lack of processing or from inhibition.