Effects of interference control on visuospatial working memory

The aim of this study was to estimate the effects on working memory efficiency of interference control mechanisms that act during selective attention on the perception of external stimuli (access) as well as the mechanisms that operate on internal representations of this memory system (deletion). These effects were examined as a function of task difficulty by increasing the memory load. Working memory performance was evaluated when access and deletion functions were active and under noninterference conditions. Subjects were able to efficiently apply the access and deletion functions during trials of low or moderate difficulty, but during trials of high difficulty, they were only able to apply the access functions and failed to activate the deletion functions. These results provide evidence supporting the independency of each of these interference control functions. Only the ability to control interference from internal memory representations is vulnerable to task difficulty and is predictive of working memory performance.