females. To emphasize the difference in the shapes, in contrast to the sizes, of the trajectories of males and females the data is also presented in the form of relative values in the middle row: each trajectory is rescaled and recentered in terms of the ratio of each of its values to the mean of the values of the trajectory taken over the entire age range of 12 to 25. The difference between the values at the beginning and at the end of the age range is the developmental change as a proportion of the mean value of the quantity represented, rather than as an absolute difference as shown in the top row. The steeper slopes of males in the relative values of theta ERO trajectories show clearly that males decrease by a much larger proportion of their mean values than females over this age range. The slopes of the male and female trajectories are explicitly shown in the bottom row, a plot of the rates of change of the mean values (developmental rates) in both the visual and auditory modalities. The male slopes are much larger in absolute value than the female slopes until about age 20. In order
