Similarity Effects in Visuospatial Working Memory

Between-item similarity strongly impacts working memory (WM) performance. Similarity effects in verbal WM have largely been documented as increasing item memory, while also decreasing memory for order. Despite the importance of stimulus similarity for theories of WM, the way similarity impacts WM performance in the visuospatial domain remains poorly understood. In one experiment, we asked thirty participants to encode sequences of 7 dots presented at different time points and different spatial locations. Between-item similarity was manipulated by modulating the spatial proximity between locations. At test, participants had to reconstruct the order of the spatial locations (memory for order) or recall the sequences from memory (item memory). While similarity decreased memory for order, it increased item memory. These findings reproduce the typical similarity effect as observed in the verbal domain, and support theories considering that visuospatial and verbal WM are characterized by the same representational properties.