The latency of the P-300 event related potential is affected by various factors, the most important of which is the ease of interpreting information conveyed by the stimulus. Using an oddball paradigm in which 20% women's names and 80% men's names were presented sequentially on a video monitor, P-300's were obtained from 15 normal subjects. Names were presented under four different viewing conditions: habitual, horizontal phoria neutralized, and with maximum base-in and base-out prism values which still allowed clear, single vision. Results showed that mean P-300 amplitudes did not differ significantly across viewing conditions. There was, however, a significant increase in the mean latencies for the phoria neutralized and base-in and base-out viewing conditions as compared to the habitual viewing condition. Using the P-300 as a measure of cognitive processing speed, this experiment indicates that there is a significant slowing of information processing when normal binocular function is disrupted with prisms.
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