The inhibition-of-return task procedure followed that of Butcher et al. [ 19].
On the other hand, in the inhibition-of-return task, the central fixation was replaced by targets.
However, regarding the leftward movements during inhibition-of-return task, the latency of eye was smaller than that of head.
However, these responses in the inhibition-of-return task are thought to be exogenously-driven automatic responses and to mark activity of the phylogenetically ancient superior colliculus [ 17].
A qualitative analysis of the trajectory of these responses revealed that head movement trajectories were steeper in the anti-saccade than in the inhibition-of-return task.
Besides, head movements of responses observed in the anti-saccade task looked steeper than those observed in the inhibition-of-return task.
Only responses occurring after the cue onset in the anti-saccade task and after the target onset in the inhibition-of-return task were included.
On the other hand, in the anti-saccade task, the medullary reticular site contributes more to the head movements than in the inhibition-of-return task.
This speculation and the functional asymmetry observed for interference with shifts of attention might support the present leftward bias of eye movements in the inhibition-of-return task.
When we compare the responses toward the side opposite the cue during the inhibition-of-return task with anti-saccades, one of the findings is that infants tend to move eyes before their head towards the left in the inhibition-of-return task.
With regard to the reaction time data of the inhibition-of-return task (Table 2), ANOVA was applied with the following factors: side (non-cued, cued), organ (eye, head), direction (leftward, rightward), and age (younger, middle, older).
