Consolidation: How information limits visual working memory capacity

Abstract

Previous research suggests that visual information exerts an impact on working memory and visual search. For example, as visual information per item increases, the number of items that can be remember decreases (Alvarez & Cavanagh, 2004; but see Awh, Barton & Vogel, 2007). Some have suggested that this is because both visual search and VWM are information-limited. But what if this is not true?What if a third factor mediated the role of information in these tasks?Here, we investigated whether consolidation time for single objects of different categories correlated with the effects of information on VWM and visual search. First, we replicated the VWM and visual search effects for a famous set of stimuli (Alvarez and Cavanagh, 2004) that included several different categories (e.g., letters, line drawings, Chinese Character, 3-D cubes, etc). Next, we assessed each person’s rate to consolidate single items from each category. We reasoned that, if consolidation time is the mediating mechanism by which information load influences both VWM capacity and visual search, then we should see systematic differences in the rate for consolidation across the various categories and these differences should correlate with measures of VWM capacity and visual search rate. To test the consolidation rate of visual information, participants saw a single target item randomly selected from one of the categories. After a variable delay, a mask appeared to disrupt consolidation, then the participant was asked to identify the item they saw from an array of options. Consistent with our predictions, consolidation rates correlated with both VWM capacity and visual search rate for these same items. This suggests that the consolidation rate could be a mechanism through which visual information influences working memory performance.