As Time Goes By

Working memory is the system devoted to the simultaneous processing and storage of information needed to perform many cognitive tasks. We present a theory that assumes that time constraints constitute the main limitation of working memory. According to our theory, processing and storage compete for attention, which constitutes a limited resource. As soon as attention is switched away, memory traces suffer from temporal decay, but they can be refreshed by bringing them back into the focus of attention. Because a central bottleneck constrains controlled cognitive activities that require attention so that they must take place one at a time, memory traces decline when the central bottleneck is occupied by processing activities. This results in a sequential functioning of working memory that alternates between processing and maintenance, leading to a trade-off between these two activities. We review empirical evidence of this trade-off and discuss its implications for the increase in working memory capacity over the course of development.