Articulatory Rehearsal Modulates Word Frequency Effect in Working Memory Tasks

Previous research has shown that long-term memory (LTM) knowledge can support working memory (WM) performance. However, the exact mechanisms remain unclear. The present study investigated the role of two WM maintenance mechanisms, attentional refreshing and articulatory rehearsal, in the short-term retention of words that are more or less easily retrievable from LTM, high- versus low-frequency words. Young adults studied a series of five (Exp. 1) or three (Exp. 2) high- versus low-frequency words in Brown-Peterson tasks. In Experiment 3, the number of words in the series varied from two to six. The opportunity to use refreshing was manipulated by varying the attentional demand of the concurrent task. Orthogonally, the use of rehearsal was either strengthened by instructions or impaired by concurrent articulation. The results showed that, when three or fewer words had to be maintained, the word frequency effect, i.e., better correct recall of high- relative to low-frequency words, was reduced in the condition where the use of rehearsal was strengthened relative to the articulatory suppression condition (Exp. 2 and 3). However, when more than three words had to be maintained, the frequency effect was evident in both conditions (Exp. 1 and 3). Finally, the frequency effect was never moderated by opportunities for attentional refreshing (Exp. 1 and 2). These findings suggest that articulatory rehearsal is at least partly responsible for the impact of LTM knowledge on WM recall performance.