The Effect Of Mental Fatigue Upon Attentive Characteristics

Driving fatigue is the one of important factors in the traffic accidents ,because it can harm a series of psychology manipulation level:the level of arouse and cognition are reduced by fatigue,especially for the attention. Moreover,the ability of attention and response will decline toward exterior environment,consequently the rate of occurring about accidents will increase. Due to the reason of causing driving fatigue is very complex,so evaluation and monitoring methods are remained in the study.With the development of brain imaging methods and cognition neuroscience, it's possible to study systematically the process of cognition and the neural mechanism of fatigue and to establish a reliable fatigue assessment system. Under experiment conditions,the method that using driving simulation to induce mental fatigue of 16 drivers was employed in the present study were used to compare the subjective evaluation with changes of objective attentive ability before and after fatigue and explore the possibility to establishing fatigue model by driving simulation,and the difference among varies methods of evaluating fatigue.The experiment consisted of three parts:(1)The Fatigue subjective scale and VAS were employed to evaluate the subjects' state of fatigue.(2)Using behavior methods,including divided attention,shifting of attention and attention span test,study the effect of attentive characteristics under the condition of driving sitmulation.(3)Different ERP modes were used to assess the features of attention in the mental fatigue.We discussed the influence of fatigue on the conflict-control and selected attention.The main conclusions of the present study are as follows:(l)The subjective evaluation did not show the significant difference,it indicated that drivers did not perceive the feelings of fatigue after driving simulation.But the attentive characteristics of drivers showed the significant difference,it suggested that six-hour driving simulation can induce fatigue,and therefore impair the function of attention.These results also suggest that subjects don not accurately and objectively evaluate their fatigue state.(2)The amplitudes of P3a and P3b were decrease after fatigue.The peak of P3a was located at frontal cortex,and the obvious advantages of the frontal cortex could be seen before fatigue,however,such advantages disappeared after fatigue. The decline of amplitudes of P3a showed the impaired function of performance after fatigue.Therefore fatigue can damage the function of performance,and impair the ability of involuntary attention and selective attention.The impairment of orient response indicated that the awareness and judgment of the signal of danger were damaged after fatigue,and the self-protection was also absent.Further,the reduction of selective attention demonstrated that the ability to respond to relative mission was declined after fatigue. (3)The amplitudes of NOGO-N2/P3 were decrease after fatigue.The obvious advantages of the frontal cortex could be seen before fatigue,however,such advantages disappeared after fatigue.It showed the impaired function of performance after fatigue.The results also support the response inhibition hypothesis.The ability to supervise the conflict information and restrain the response was attenuated,indicating that less psychological resources were allocated for performance after fatigue.Thereby,it limits the process of response inhibition,and impair the deeply processes of conflict information.These results show that mental fatigue can impair varies response process and decline the function of information process.To sum up,the attentive characteristics of drivers were changed by fatigue, say,they were impaired,even though they did not perceive the feelings of fatigue. Especially ERP as an indicator is more objective and sensitive,and can indicate the generation mechanism about fatigue.It's believable that human beings will get more systematic understanding about neurobiological bases of driving fatigue and fund more scientific evaluation indicator and monitor method for driving fatigue with the development of cognitive neuroscience,brain neuroimaging and electrophysiological technology.