Amplitude of saccades is modulated by the nature of visual stimuli and saccade accuracy in saccadic choice tasks

Studies using saccadic choice task (where participants have to initiate saccades toward a target image presented along with a distractor image in the opposite visual field) showed faster and larger saccades toward face targets than other stimuli. Error saccades were also found to be shorter than correct ones, suggesting an online correction. To better control saccade amplitudes, we did a new saccadic choice experiment in which participants had to saccade toward a central cross added on images. We still observed hypometric saccades (1) for saccades toward vehicles compared to faces and (2) for error saccades which were followed by corrective saccades with very short latencies. These results suggest a parallel programming of saccades toward both images. The two saccade programs interact and interfere with each other and would be weighted by the saliency of the target, affecting saccade amplitude.