ERP Study On The Effects Of Mental Fatigue On Selective Attention

When people are working on a cognitively demanding task for aprolonged period of time, they will often experience mental or cognitive fatigue, reflected in deteriorated task performance andreduced motivation to continue to work on the task at hand. Moreover, an increase in the amount and severity of errors being made can generally be observed. The effect of mental fatigue about daily life and work often happened silently.The reserches about mental fatigue started lately in our country.There are little reserches about mental fatigue in the beginning, most of them are the conclusion and analyse of foreign study. Reserches about mental fatigue is getting people’s attention in the1990s. As the development of neuroscience, physiological, and the deeper reserches about mental fatigue, more and more physiologic indexes are using to detect the level of mental fatigue, include heart rate(HR), heart rate varibility (HRV), electroencephalogram (EEG), Event related potenals(ERPs), respiration rate (RR), eye blinke, pupil diameter, skin resistance, body temperature and so on.Selective attention is one of the most developed sector of modern cognitive psychology and nuroscience. The studies of the restrain ability of selective attention are very common in cognitive psychology. The usual attention restrain study paradigm are motor response inhibition and disturbance control.ERP is an sensitive and meanful index of information prcessing, which is wide spread in cognitive psychology and clinical study. It reflected the electroneurophysiology changes in the cognitive progess, which is the brain skin potenials recording while people reacting at some stimlus. ERP is extracted from EEG. As the development of computer science, ERP is using more and more often.ERPs and Fuctional Magnetic Resonance Imaging(FMRI) is playing an important part in recent reserches, espically in the cognitive reserches.However, how the mental fatigue affect the selective attention? There are studies showed selective attention has different restrain and promote progess. Whether mental fatigue has the same kind of effect by these two mechanism? And if the influence of mental fatigue to selective attention is decided by itself or just as regular is wait for reserch.Base on all these stuff, we propose some hypothesis:1, Mental fatigue can be indued by a long term of selective attention, and cause to the subject resistance to continue the experiment.2, The performance of selective attention is effected by mental fatigue.The reaction time will increase and the accuracy will decrease.3, With time on task, mental fatigue gradully produce and influence the early compoment of the ERPs of selective attention.4, P300is a key index of mental fatigue. The amplitude of P300of selective attention will change with the time on task.The effects of mental fatigue on attention were assessed. Subjects performed a visual attention task for1.5h without rest in laboratory environment. Subjective levels of fatigue, performance measures and ERP were recorded and analysed. The main results and conclusions of this study are as follows:1,Subjective fatigue ratings, as well as the time of task increased, suggesting that the almost2h of task performance resulted in an increase in fatigue.2, Reaction times, misses increased with time on task, indicating decreased performance efficiency in fatigued subjects.3, No change in P1amplitude with time on task could be observed. N1amplitude decreased with time on task independent vs stimlus type.4, P300amplitude decreased with time on task. There is no difference in P300amplitude between compatible and incompatible stimulus before the fatigue was induced. With time on task, the P300amplitude of incompatible stimlus decreased slower compair to the compatible stimulus. It may revolved to the decrease of ability of work memory with time on task.