The varying nature of semantic effects in working memory.

Several studies have demonstrated an influence of semantic knowledge on verbal working memory (WM) performance, such as shown by the observation of semantic relatedness (related vs. unrelated words) and word imageability (high vs. low imageability words) effects in working memory. The present study extends these observations by examining in four experiments the extent to which semantic knowledge can protect WM representations against interference. We assessed immediate serial recall performance for semantically related vs. unrelated word lists and for high vs. low imageability word lists, with memory lists being followed by an interfering task after encoding or not. Results show that semantic relatedness leads to a stronger protective effect against interference than word imageability at the item level. Furthermore, the semantic relatedness had a stronger impact on WM performance than word imageability; this was further supported by a meta-analysis of all relevant studies in the field. These results suggest that inter-item associative semantic knowledge can protect WM content against interference, but less so item-level semantic knowledge. This protective effect may result from between-item recurrent reactivation or from reduced cognitive load via the compression of memoranda into conceptual units, as further supported by a series of computational simulations.