Finding memory in search: The effect of visual working memory load on visual search

Abstract

There is now substantial evidence that during visual search, previously searched distractors are stored in memory to prevent them from being reselected. Studies examining which memory resources are involved in this process have indicated that while a concurrent spatial working memory task does affect search slopes, depleting visual working memory (VWM) resources does not. In the present study, we confirm that VWM load indeed has no effect on the search slope; however, there is an increase in overall reaction times that is directly related to the number of items held in VWM. Importantly, this effect on search time increases proportionally with the memory load until the capacity of VWM is reached. Furthermore, the search task interfered with the number of items stored in VWM during the concurrent change-detection task. These findings suggest that VWM plays a role in the inhibition of previously searched distractors.

Keywords:

• Visual working memory
• Visual search
• Attention
• Inhibition
• Dual-task interference

Acknowledgments

Thanks to Steve Thomas for help with data collection. This research was supported by Natural Sciences and Engineering Research Council of Canada (NSERC) grants to S.F. and J.P. and a Canadian Institutes of Health Research (CIHR) grant to S.F. (Reference No. 79256).

Notes

¹ The RTs in both the no memory and the memory conditions converge at a set size of one because nothing is inhibited prior to the selection of the first item, and so memory plays no role on establishing the initial RT. Further, the inflection point in RTs (the point at which the slope changes) occurs at one item above capacity—if three items were inhibited, the fourth item is the first item that will be searched with replacement, making it the origin of the change in slope.