A secondary task is not always costly: Context-based guidance of visual search survives interference from a demanding working memory task

Abstract

Repeatedly encountering a visual search display with the target located at a fixed position relative to the distractors facilitates target detection, relative to novel displays - which is attributed to search guidance by (acquired) long-term memory (LTM) of the distractor 'context' of the target. Previous research has shown that this 'contextual cueing' effect is severely impeded during learning when participants have to perform a demanding spatial working memory (WM) task concurrently with the search task, though it does become manifest when the WM task is removed. This has led to the proposal that search guidance by LT context memories critically depends on spatial WM to become 'expressed' in behaviour. On this background, this study, of two experiments, asked: (1) Would contextual cueing eventually emerge under dual-task learning conditions if the practice on the task(s) is extended beyond the short training implemented in previous studies? and given sufficient practice, (2) Would performing the search under dual-task conditions actually lead to an increased cueing effect compared to performing the visual search task alone? The answer is affirmative to both questions. In particular, Experiment 1 showed that a robust contextual cueing effect emerges within 360-720 dual-task trials as compared to some 240 single-task trials. Further, Experiment 2 showed that when dual- and single-task conditions are performed in alternating trials blocks, the cueing effect for the very same set of repeated displays is significantly larger in dual-task blocks than in single-task blocks. This pattern of effects suggests that dual-task practice eventually leads to direct, or 'automatic', guidance of visual search by learnt spatial LTM representations, bypassing WM processes. These processes are normally engaged in single-task performance might actually interfere with direct LTM-based search guidance.

Keywords: contextual cueing; search guidance; visual search; working memory.