The Effect of Mental Fatigue on the Response-Time and Error-Rate of Cyclic Tasks in ACT-R Cognitive Architecture

This study was designed to investigate the effect of mental fatigue on response-time and error-rate of cyclic tasks using a simulated model in ACT-R cognitive architecture. The effects of fatigue on cyclic tasks with high frequency and long duration have not thus far been systematically studied. In the present study، an unvarying cyclic task was modeled in ACT-R (Adaptive Control of Thought-Rational) environment. For each run، the average response-time per cycle and total error-rate were obtained through dividing the total working time and total number of incorrect responses، respectively by the total number of cycles after eliminating the learning phase. Then، the effect of mental fatigue was studied in the cognitive architecture and a fatigue-based multiplier was incorporated into the model. This multiplier was a concentration index which was declined when response-time and error-rate increased. Next، real data were collected through experiments on volunteers and compared with simulated results using analysis of variance (ANOVA). After validation of the model، the impact of fatigue-based multipliers on the response-time and error-rate were analyzed for different iteration numbers. Using an F test at α=0. 05، no significant disagreement between virtual and real data and the validity of the model was shown. Final results for 3-sec cycle tests revealed up to 0. 5 sec increase in the average response-time for each cycle and 12% in the average error-rate. After 1000 iterations of the sample task، the average response-time for each cycle and the average error-rate are increased by 0. 43 sec and 8%، respectively. This confirms the negative impact of mental fatigue on such indices. Such an effect can be administered and controlled by proper rest breaks.