Modulation of microsaccade rate by task difficulty revealed through between- and within-trial comparisons

Microsaccades (MSs) are small eye movements that occur during attempted visual fixation. While most studies concerning MSs focus on their roles in visual processing, some also suggest that the MS rate can be modulated by the amount of mental exertion involved in nonvisual processing. The current study focused on the effects of task difficulty on MS rate in a nonvisual mental arithmetic task. Experiment 1 revealed a general inverse relationship …