Spatial information with pictures and words in visual short-term memory

In a delayed matching task, the influence of spatial congruence between study and test on visual short-term memory for geometric figures and words was investigated. Subjects processed series of pictures which showed three words or three geometric figures arranged as rows or as triangular configurations. At test, the elements were presented in the identical or in the alternative configuration as at study. In the non-matching case, one of the studied elements was exchanged. The delay was 5 s. Subjects judged whether the elements were the same as during study, independent of their configuration. In Exp. 1, pictures of figures and words were mixed within one list. For both modalities, the response times were longer if the configuration at test was incongruent to the one at study. This contradicts the results of Santa, who observed effects of spatial congruency for figures, but not for words. In Exp. 2 we therefore presented the same material as in Exp. 1, but now the lists were modality-pure, as in the experiment of Santa--i.e., words and figures were shown in different lists. This time, spatial incongruency impaired recognition of the figures, but not recognition of the words. These results show that in a non-verbal context, isolated visually presented words are spatially encoded as non-verbal stimuli (figures) are. However, the word stimuli are encoded differently if the task is a pure verbal one. In the latter case, spatial information is discarded.