Interaction between lateralization of memory and probe stimulus in the recognition of verbal and spatial visual stimuli.

The aim of the study was to sort out whether in normal subjects hemispheric asymmetries in memory encoding arise at the input or at the recognition stage of verbal (diagrams of letters) and spatial patterns (diagrams of stars) in a 3 X 3 virtual matrix. Target and probe stimuli were tachistoscopically presented to the same or the opposite hemisphere. Letters, but not stars, were better recognized in a crossed condition in which targets were flashed to the right and probes to the left hemisphere. The finding suggests that the right hemisphere (but not the left) is capable of adding specific, possibly mnestic, resources to the first stage of letter processing.