THE EFFECTS OF MEMORY LOAD IN VISUAL SEARCH ARE MODULATED BY SIMULARITY BETWEEN THE MATIRIALS INVOLVED
The effect of memory load in visual search has shown a high heterogeneity of results: while some researchers have found an impairment of performance under high memory load conditions (eg. Lavie & De Fockert, 2006), others have found no effect of memory load (eg. Woodman, Vogel & Luck, 2001), and even others have found an improvement of performance under high memory load conditions (Smilek, Enns, Eastwood, & Merikle, 2006). In the present research we propose that the relationship between the material retained in working memory (WM) in a secondary memory load task and the target and distractors involved in the visual search task might be a key factor for explaining the discrepancies in the results. We tested our hypothesis manipulating that relationship in four experiments. The results show that the relationships between the material in WM and the target and distractors in the attentional task may be a crucial factor in modulating the effect of memory load in visual search. If the items retained in WM are similar to those presented as targets in the attentional task, visual search performance improves under high memory load conditions. On the contrary, if the items retained in WM are similar to those employed as distractors in the visual search task, there is no modulation of memory load in visual search. Finally, we discuss the theoretical implications in the context of the endogenous and exogenous attentional processes involved in visual search.