Exploring developmental differences in visual short-term memory and working memory.

Although visuospatial short-term memory tasks have been found to engage more executive resources than do their phonological counterparts, it remains unclear whether this is due to intrinsic differences between the tasks or differences in participants' experience with them. The authors found 11-year-olds' performances on both visual short-term and working memory tasks to be more greatly impaired by an executive suppression task (random number generation) than were those of 8-year-olds. Similar findings with adults (e.g., Kane & Engle, 2000) suggest that the imposition of a suppression task may have overloaded the older children's executive resources, which would otherwise be used for deploying strategies for performing the primary tasks. Conversely, the younger children, who probably never had the capacity or know-how to engage these facilitative strategies in the first place, performed more poorly in the single task condition but were less affected in the dual task condition. These findings suggest that differences in the children's ability to deploy task-relevant strategy are likely to account for at least part of the executive resource requirements of visual memory tasks.