Spatial-positional association of response codes is modulated by the number of items in working memory.

The SPoARC (spatial-positional association of response codes) effect refers to a mental spatialization of ordinal information in working memory. In the present study, we investigated how spatialization can be modulated by the number of items to be maintained in working memory. In Experiment 1, 139 participants performed a spatialization task with sequences of either two, three, four, or five items using a between-subjects design. The results showed a significant spatialization effect for all sequence lengths except for sequences of five items. In Experiment 2, 96 participants performed the same spatialization task for sequences of three, four, and five items, but using a within-subject design. The results confirmed the absence of a SPoARC effect for sequences of five items, and showed a greater effect for sequences of four items. Overall, our findings suggest that working memory load is a moderator of the spatialization effect. In addition, we found that spatialization was in part modulated by participants' spatial abilities.