Visual similarity effects in immediate verbal serial recall

The role of visual working memory in temporary serial retention of verbal i nformation was examined in four experiments on immediate serial recall of w ords that varied in visual similarity and letters that varied in the visual consistency between upper and lower case. Experiments 1 and 2 involved wor ds that were either visually similar (e.g. fly, cry, dry; hem, new, few) or were visually distinct (e.g. guy sigh, lie; mho, blue, eme). Experiments 3 and 4 involved serial recall of both letter and case from sequences of let ters chosen such that the upper- and lower-case versions were visually simi lar, for example Kk, Cc, Zz, Wm, or were visually dissimilar, for example D d, Nh, Ru, Qq. Hence in the latter set, case information was encoded in ter ms of both the shape and the size of the letters. With both words and lette rs, the visually similar items resulted in poorer recall both with and with out concurrent articulatory suppression. This visual similarity effect was robust and was replicated across the four experiments. The effect was not r estricted to any particular serial position and was particularly salient in the recall of letter case. These data suggest the presence of a visual cod e for retention of visually presented verbal sequences in addition to a pho nological code, and they are consistent with the use of a visual temporary memory, or visual "cache", in verbal serial recall tasks.