Adaptive use of semantic representations and phonological representations in verbal memory maintenance

•Individuals rely on phonological representations in serial recall of words.•The word length effect (WLE) reflects the use of phonological representations.•The WLE disappeared by preventing articulation when keeping high-imageable words.•The same occurred by the instruction to use a semantic strategy.•The latter was clear in participants who are good at keeping semantic representations. Findings from serial recall tasks, such as a recall disadvantage for long words (known as the word length effect or WLE), have suggested that individuals rely on phonological representations to perform immediate serial order recall of words. Findings from synonym recognition tasks suggest that individuals can also use semantic representations in immediate memory. This leads to the idea that individuals can switch from relying on phonological representations to relying on semantic representations according to demands of ongoing cognitive activities. This study investigated the WLE under articulatory suppression and when following the semantic instruction in serial recall of words of high and low imageability. In addition, the study investigated whether the WLE is affected by individual differences in capacity for maintaining semantic representations that are measured by the synonym recognition task. The results demonstrated that the WLE disappeared when maintaining highly imageable words but was still observed when maintaining words of low imageability under articulatory suppression. Moreover, the semantic instruction eliminated the WLE only in individuals who could perform the synonym recognition task well. These results provide clues to understanding the adaptive use of semantic and phonological representations in verbal working memory.