The practice block consisted of 12 trials in which each of the four models was presented with a neutral expression. On each trial, gaze was either direct or averted to the farthest positions (nine pixels) to the left or right. During practice trials, participants received feedback indicating whether their responses were correct or not (a cartoon image of a happy face with a 1,000 Hz tone for correct responses and a cartoon image of a sad face with a 400 Hz tone for incorrect responses). Participants were allowed to repeat each practice block up to two times to reach a criterion of 75 % accuracy. Sixteen participants in the ASD group and 15 participants in the typical group met this criterion on the first attempt, for both the upright and inverted blocks. Two participants in the typical group required a second attempt to reach criterion in the inverted block. One participant in the ASD group was replaced for failure to reach this criterion within three