Sex differences in change over time in perceptual asymmetry

Male (N = 36) and female (N = 43) subjects were given a 120 trial, fused dichotic word test. Males showed higher right ear advantages on the first 60 trials, that then decreased over the next 60 trials. Females showed lower right ear advantages on the first 30 trials, that then increased. The two groups had equal mean asymmetry scores for the last 60 trials. These data suggest that males respond to the novelty of a new task with relative left hemisphere activation while females respond with relative right hemisphere activation. There are no previous reports of sex differences in changes in asymmetry over time.