Semantic characteristics do not influence spatialization in working memory

Serial order has been suggested to be represented spatially along a working memory line, oriented from left to right in Westerners. Such spatial coding of order is evidenced by the SPoARC (Spatial Positional Association of Response Codes), showing faster left-hand responses to early items in a sequence and faster right-hand responses to late items. Although this effect has been preferentially linked to semantic processing, the origin of the phenomenon remains unclear. In this study, we investigated the contribution of semantic content and semantic richness in the emergence of the effect. We asked 141 participants to perform a recognition task with stimuli whose semantic properties were manipulated using pseudowords, abstract words, and concrete words. We observed a spatialization effect using pseudowords, challenging the semantic hypothesis suggested in the literature. In addition, we did not detect any differences in spatialization between abstract and concrete words, suggesting that semantic richness does not influence this process. These results tend to indicate that semantic characteristics do not contribute to the emergence of spatialization in working memory. We suggest instead that the SPoARC would primarily stem from phonological processing.