Inhibition theory and the concept of perseveration. In the past few years several models have been proposed in order to account for the long term trend and the possible interdependency of the responses or reaction times in prolonged work tasks. In a prolonged work task subjects are required to engage in simple, repetitive activities, such as letter cancellation, detecting differences in simple shapes, adding three digits, and so on.
Performance is recorded as a series of reaction times.
Each individual reaction time is modelled as the sum of a series of alternating real working times and distraction times, both of which are latent variables. Only the reaction times are observable. Reaction time curves obtained in overlearned prolonged work tasks usually show an increase at the beginning of the test and, after some time, reach a stationary state. According to inhibition theory, if the initial inhibition at the beginning of the task deviates from its stationary value, then it will be some time for the stationary state to be reached. The phenomenon of increasing reaction time curves can be explained by assuming that the inhibition at the beginning of the task is lower, because in a state of non-work, in the period before the task, the inhibition will fluctuate at a lower level than in a state of work during the task.