Abstract
Post-exposural directional scanning and cerebral dominance are major postulates which account for lateral differences in tachistoscopic perception. These ideas can be integrated when tachistoscopic perception is viewed as a short-term memory task. Briefly exposed stimuli not only have to be scanned, but also rehearsed, subvocally, before they can be encoded. Since most Ss are left-hemisphere dominant for language, scanned information arriving in the right hemisphere has to be sent to the left hemisphere for rehearsal. This transmission effects a loss of scanned information because it is held in a rapidly dissipating storage. These ideas account for lateral differences found with vertically and horizontally oriented targets, but methodological considerations are discussed which indicate that these notions are more clearly demonstrable with the former than latter displays.