Objectives: The study aimed to investigate whether there was any difference in perception of interactional synchrony between PDD and non-PDD groups.
Methods: 26 adults(14 with PDD and 12 without PDD) with typical IQ participated in a visual task. They were shown a movie assembled from three sectional videos located in the middle left, the upper right and the lower right of the movie screen. In the experimental condition, the left video showed one of the two interactants while each of the right videos showed the other one. In the control condition, the left video showed the bottom-side of a drum being hit with a drumstick while each of the right videos showed small pieces of paper being scattered on the top-side of the drum. In both conditions, the two right videos were muted and only one of them was synchronized to the left video. The task of participants was to find out which of the right videos synchronized. Reaction time (RT) and eye movement during the task were recorded.
Results: In the experimental condition, RT in the PDD group was significantly longer than in the non-PDD group. In the control condition, RTs in both groups were not significantly different. In the experimental condition, the number of fixations in the PDD group was significantly bigger than in the non-PDD group. In the control condition, the numbers of fixations in both groups were not significantly different. In both control and experimental conditions, fixation durations in both PDD and non-PDD groups were not significantly different.
Conclusions: The findings suggested that in the experimental condition, the perception of synchrony was worse in the PDD group than in the non-PDD group.