Abstract
One prominent model of visuo-spatial working memory proposes overlapping mechanisms for the retention of spatial and visual information (Baddeley & Logie, 1999). Although several lines of evidence point to an attention-based rehearsal mechanism (Awh, Jonides, & Reuter-Lorenz, 1998) for the retention of spatial information, there is no obvious way to extend this idea to the retention of visual but non-spatial information such as color. The visuo-spatial working memory model proposes a passive cache for such visual information. One prediction from this model is that distracting auditory secondary tasks performed during the memory delay will have no effect on memory for visual information, since a passive store has no requirement for attention-demanding rehearsal of information. The logic of dual-task experiments is that if requiring completion of a second task during the memory delay for a primary task interferes with performance on the primary task, then both tasks must compete for a single resource or mechanism. We tested this idea by comparing individual observer's memory for color or pattern (Phillip's squares, Phillips & Christie, 1977) in trials with no secondary task during the memory delay with the same individual's dual-task performance. We find that memory for color is remarkably robust against the effects of secondary tasks, whereas memory for patterns is quite vulnerable. This is consistent with a model where color memory is maintained by a passive mechanism and pattern memory requires attentive rehearsal. This may prove to be the same spatial attention mechanism proposed for spatial working memory.
Funding acknowledgements: Visual Knowledge of Objects, R01 MH070850