EFFECTS OF EXPOSURE TIME ON FACE RECOGNITION LATENCY TASK AND OBJECT NAMING LATENCY TASK PERFORMANCE

Sergent (1982a, 1982b) has suggested that the cortical hemispheres are differentially specialized for the analysis of high and low stimulus intensities. The right hemisphere is believed to be specialized for processing low stimulus intensities, while the left hemisphere is dominant for processing high stimulus intensities. According to this view, shorter exposure times favor better right than left hemisphere performance, while longer exposure times favor better left than right hemisphere performance on tachistoscopic laterality tasks. This effect is believed to be independent of the verbal or nonverbal nature of the experimental stimuli. Sergent's views, while indeed provocative, are not adequately supported by the laterality literature. Results of previous research suggested a possible alternative hypothesis (herein referred to as the Efron hypothesis) which proposed that conditions of low stimulus intensity (short exposure times) would increase the magnitude of the visual half-field effects typically obtained with a given task. Conversely, conditions of increased stimulus intensity would result in a decrease in the magnitude of the usual visual half-field effects. The present study examined the effects of a three-fold variation (40 msec versus 120 msec) in exposure duration, with constant 3 mL luminance, on face recognition and object naming laency task performance. These are the same stimulus parameters employed by Sergent (1982b) in a task with which she demonstrated an exposure time influence on performance asymmetries. Present results demonstrated the expected left visual field superiority for the face recognition task and right visual field superiority for the object naming latency task. There was, however, no influence of exposure duration on the performance of either task. This finding is inconsistent with Sergent's position and also provides no support for the Efron hypothesis. It was concluded that these tasks, which tap established lateralized processing asymmetries, are very robust and resistant to exposure time influence.