Why does memory span improve with age? A review of the evidence for two current hypotheses

Abstract

Evidence for two major hypotheses that attempt to explain the development in memory span with age is reviewed: the identification time hypothesis and the rehearsal hypothesis. The rehearsal hypothesis is also strongly related to the recent application of the working memory model to memory development. In this model, rehearsal is assumed to occur from an extremely young age. This assumption is critically evaluated. It is concluded that there is no strong support for the identification time hypothesis, except as a facet of familiarity. Neither was there good evidence that very young children use verbal rehearsal, although it did appear to be a factor later on. A revised model is proposed, based on three factors. The first is a speech perception system and phonological store; the second is a speech output system which can be used for sublexical segmentation and later rehearsal. The third system is long-term memory with links to both the speech perception and speech output systems. These links enable active strategies to be developed.