Spatial working memory load impairs signal enhancement, not attentional orienting

Abstract

The current study examined the effect of spatial working memory load on spatial cuing effect. It is well known that spatial working memory and spatial attention functionally overlap or share a common resource. Awh et al. (1998) showed visual selection played a critical role in the maintenance of spatial information. Based upon this finding, we expected that the improvement in behavioral performance by attention would interact with spatial working memory. Two experiments were conducted to test this hypothesis. Participants were given a transient cue predicting the location of a relevant item and they had to perform a visual discrimination task with or without maintaining four locations in working memory. Cuing effect measured by reaction time did not differ either in the presence or in the absence of spatial working memory load. However, spatial working memory load reduced cuing effect in accuracy. This discrepancy can be explained by distinction between channel selection and channel enhancement by attention (Prinzmetal et al., 2005). The benefit in RT by attention shows prioritization of the attended location (channel selection), whereas the improvement in accuracy under data-limited conditions reflects the enhancement of perceptual representation on the attended location (channel enhancement). Given the fact that spatial working memory load reduced only the attentional advantage in accuracy, we conclude that spatial working memory load impairs signal enhancement on the attended location, but seems to be irrelevant with attentional orienting per se.