Semantic similarity interacts with serial order processing in short-term memory

Background: Verbal short-term memory (VSTM) is a cognitive function allowing the temporary storage of linguistic information. This function strongly rely on stored long-term memory (LTM) knowledge: verbal items associated with richer LTM representations are better recalled in VSTM. These LTM aspects are generally considered as being independent from serial order processing, that is, the ability to maintain the order in which verbal items appear within a sequence. The purpose of this study was to demonstrate that serial order processing in VSTM can also interacts with LTM knowledge, focusing more specifically on the interactions with semantic knowledge.

Method: Forty participants performed a VSTM task in which they were invited to listen and recall in the correct serial order lists composed of 6 words; verbal lists were either semantically related or they were not. The words were grouped by groups of 3 semantically related words (e.g. three, leaf, branch, cloud, sky, rain) in the related condition.

Results: We observed no effect of semantic grouping on the proportion of order errors. However, semantic grouping dramatically influenced the pattern of transposition errors: while statistically less inter-group transpositions (i.e. erroneously recalling one item from one semantic category to another) were observed in the related condition, we also observed statistically more intra-group transpositions (i.e. transposing two items within the same semantic category).

Discussion: These results show that semantic knowledge can influence serial order processing in VSTM. They also support recent theoretical proposals stating that serial order processing strongly interact with the activation within the semantic system.