On the relationship between cognitive load and the efficiency of distractor rejection in visual search: The case of motion-form conjunctions

Abstract

ABSTRACT Search for a target defined by a conjunction of movement and shape (moving X amongst moving Os and static Xs) is efficient, with static distractors contributing little to RT. How search is restricted to the moving items, whilst static items are ignored is not fully understood. Whether, passive bottom-up, or active top-down control processes are recruited is unknown. The current study addressed this question by asking participants to search for a motion–shape conjunction target under a low (one-digit) or high (six-digit) memory load. In Experiment 1, the number of distractors with target motion (moving Os), shape (static Xs), or neither (static O) was varied. RT was most sensitive to the number of moving items, less sensitive to the number of target-shaped items, and insensitive to the number of items without target features. A six-digit load slowed responding, but the effect of increasing distractor numerosity remained unchanged. Experiment 2 compared conjunction against feature (moving X amongst moving and static Os) search. Both searches were slowed by a high memory load but search slope remained unchanged. The results are consistent with the idea that sustained distractor rejection in motion–form conjunction search is largely insensitive to cognitive load.