The relationship of the latency of the visual P100 wave to gender and head size.

Six separate recordings of the pattern-reversal visual evoked potentials of 8 male and 8 female healthy adults were made. The average resulting latencies to P100 (LP100) were correlated with head length and circumference as well as with gender and latency to N70 (LN70). There was better correlation of LP100 with head circumference than with gender, and no significant correlation of LP100 with head length or with LN70. Also, using head circumference as a predictor of LP100, the addition of gender to the regression equation did not improve the prediction. These results indicate that a major determinant of differences in LP100 in adults is head size rather than gender. These differences are suggested to be due to differences in the geometry of the head rather than to more general biological differences between males and females.