MENTAL FATIGUE AND THE EFFICIENCY OF INFORMATION-PROCESSING IN RELATION TO WORK TIMES

Mental fatigue was studied by analysing performance and mental effort in a memory search task in relation to the temporal structuring of pre ceding work periods. Performance was measured by reaction time and err or rate. Mental effort was measured via spectral analysis of the 0.10 H-2 component in the heart rhythm signal. It was shown that subjects p rotected their performance by spending more effort in the unfavorable conditions: after several hours of work and after continuous work with out short rest breaks. In the most unfavorable condition, after 8 h of work combined with sleep loss, the efficiency of information processi ng broke down. Performance could no longer be protected by invested ef fort. This breakdown phenomenon is interpreted as a serious sign of me ntal fatigue.