Integration of learning and forgetting processes with the SHERPA model.

The present paper is targeted to address the impact of the learning and forgetting processes on the system performance during the working activities in combination with the human error quantification. The Learning and Forgetting Curves Model (LFCM) has been implemented as a new module in the SHERPA simulator, developed for the human error assessment. The LFCM module assumes, according to the literature, that human performance improves with the increase in cumulative production, leading to a progressive reduction of the processing times. On the contrary, the performance deteriorates when learning sessions are separated by rest breaks that cause knowledge depreciation or forgetting. The paper provides a different model to measure the system performance when the learning and forgetting processes are present, considering at the same time the productivity and the error probability. The model has been applied to a case study showing interesting results in terms of learning and forgetting processes effects on the system performance.