Is visual working memory capacity driven by mental imagery strength?

Abstract

Visual working memory provides an essential link between past and future events. Here we measured visual working memory using a two alternative forced choice paradigm. To assess capacity observers were required to remember the orientation of each element in a circular array of different set sizes, composed of small Gabor patterns. We then assessed the strength of mental imagery in each observer using the previously documented binocular rivalry technique. Individuals with strong visual mental imagery had a greater visual working memory capacity than those with intermediate or poor imagery. However, mental imagery strength did not predict the capacity limits in a number working memory task. In addition, increasing the background luminance during the retention interval reduced the visual working memory capacity (of good imagers), but not their number working memory capacity. Likewise, increased background luminance during imagery generation attenuated the effects of mental imagery on subsequent perception (only for good imagers). This suggests that luminance signals were disrupting visual sensory-based mechanisms and not a general working memory system. These results suggest that visual working memory, but not number working memory capacity is closely related to an individual’s imagery strength. We hope these findings might help reconcile current controversy regarding the mechanism and neural location of visual mnemonic storage. Meeting abstract presented at VSS 2012