Is the attentional boost effect really a boost?

摘要

When performing two tasks at once, increasing attention to one task typically impairs performance of the other. In contrast, the attentional boost effect suggests that dual-task facilitation can also sometimes occur: Memory for images that coincide with an unrelated stimulus that requires a response (target) is better than memory for images that coincide with a stimulus that requires no response (distractor). This performance advantage reflects a difference in memory for images presented with targets relative to those presented with distractors. As a result, it could reflect either an enhancement triggered by target detection or inhibitory processes triggered by distractor rejection. To determine whether the attentional boost effect is truly a boost, a baseline measure of image memory under dual-task encoding conditions is necessary. In several experiments participants memorized a series of continuously presented faces while monitoring a second series of unrelated squares. The face could appear in three different encoding conditions: on its own, with a square that required a response (target), or with a square that required no response (distractor). Processes associated with both target detection and distractor rejection were minimized when faces appeared on their own, making this condition suitable as a baseline measure of face encoding. Consistent with the claim that the attentional boost effect is triggered by target detection, the data showed that memory for faces coinciding with a target square was enhanced relative to faces in both the baseline and distractor conditions. There was no evidence of a difference in memory for faces in the baseline and distractor conditions. We conclude that detecting a behaviorally relevant event boosts memory for concurrently presented images in dual-task situations.