Abstract: The oculo-motor reflects the viewer's ability to process visual information. This paper examines whether the oculo-motor was affected by two factors: rstly task dif culty and secondly eye-movement frequency. In this paper, oculo-motor indices were de ned as measurements of pupil size, blink and eye-movement. For the purpose of this study, two experiments were designed based on previous subsequential ocular tasks were subjects were required to solve a series of mathematical problems and to orally report their calculations. The results of this experiment found that pupil size and blink rate increased in response to task dif culty in the oral calculation group. In contrast however both the saccade occurrence rate and saccade length were found to decrease with the increased difficulty of the task. The results suggests that oculo-motor indices respond to task difficulty. Secondly, eye-movement frequencies were elicited by the switching frequency of a visual target. Pupil size and the saccade time were found to increase with the frequency however, blink and gazing time were found to decrease in response to the frequency. There was a negative correlation between blinking and gazing time. Additionally, the correlation between blinking and saccade time appeared in the higher frequencies.These results indicate the oculo-motor indices are affected by both task difficulty and eye-movement frequency. Furthermore, eye-movement frequency appears to play a different role than that of task difficulty.