The Effect Of Mental Fatigue On The Size Of Pupil During The Cognition Choice Process

There has been a great increase in the number of white-collar workers with the development in technology, and one of the most important causes for mental fatigue is today’s fast-paced lifestyle. Long simple repetitive tasks during daily work may cause workers to be dreary of the work, the difficulty of the tasks will consume a lot of motivation and eventually lead to mental fatigue which would cause cognition deficiency such as decreases in motivation, increases in error rate and prolonged reaction time. Eyes are the most directly affected organs when human beings receive externally stimulation; the changes in their sizes are influence by the sympathetic and parasympathetic nerve systems, When people feel mentally tired, the nervous system will be affected. The hypothesis of this research was that there’ll be obvious changes in the pupils which indicates the person is experiencing symptoms of mental fatigue.The article chooses university students to be the testees, and the main objective of this essay is to find out whether mental fatigue caused by the length and difficulty of the tasks would have an influence on the size of the pupil during the process of cognition choice, through the experimentation and accessing method.Two experiments were performed for the purpose of this research. The first experiment involved testing twenty university students with no difference in age and sight using self-made ball pictures as stimuli. The stimulation materials were incorporated in the E-prime software to produce a selective test procedure. The total length of this experiment is two hours with each stimulation showing3000milliseconds and intervals of500milliseconds. This experiment was to observe the condition of the pupil through the prolonging of the tasks that caused mental fatigue. The second experiment involved another twenty students. First hour of this experiment was identical to the first experiment as mentioned above, however, in the second hour, the difficulty was increased and the time of each stimulation showing was shortened to2000milliseconds, which requires the testees to finish more difficult tasks within a shorter time.We discovered through the experiments that by the end of the first experiment, the size of the pupil was much smaller than when started, the difference was significant. This means that during long simple repetitive cognition selecting tasks, the difficulty level was low so the testees do not need to pay much effort, with the increase of time the interest were declining which led to mental fatigue and eventually the decrease in pupil size. At the same time, during interviews conducted with the testees after the end of experiments, we found out that the students all described the test as painful, as the experiment progresses, the feelings of "painful" and "irritating" were worsened. In the second experiment, as the difficulty of tasks increased, the size of pupil was increased, and the difference was significant. However comparing with the size of pupil afterwards there’s not much difference. This means, with the increase of task difficulty, the testees paid more effort which lead to a sudden increase of tension with in the nervous system, and the pupil enlarges and was relatively stable for a period of time. To some extend, the length and difficulty of tasks have antagonistic effect on the size of the pupil.