Figure 2

The temporal dynamics of the microsaccade rate and the modulations of perceptual load on the microsaccade rate during different time periods. (A–C,E–G) Temporal dynamics of the microsaccade rate during the easy (blue) and hard (pink) tasks for monkeys G (top panels) and N (bottom panels). The four vertical black lines indicate cue onset, cue offset, stimulus onset and target color change, respectively. The two horizontal dashed lines represent the baseline rate of microsaccades that occurred 150 ms before the cue onset (blue for the easy task and pink for the hard task). The gray lines at the top show the times of the Control and Periods 1, 2 and 3 in Fig. 1. The black lines at the bottom of each plot denote the periods in which the microsaccade rate under the two conditions differed significantly (p < 0.05, Student t test). (D,H) Comparisons of the perceptual load modulation on the microsaccade rate during different periods. For each monkey, the top panel shows the average microsaccade rate during the easy (blue) and hard (pink) tasks within different periods. The bottom panel shows the perceptual load modulation induced by task difficulty on the microsaccade rate (DMI). Error bars in all panels indicate SEM, and asterisks represent statistical significance (***p < 0.0001, **p < 0.001, *p < 0.05).