Knowledge of results and intertrial correlations in a simple motor task

Lever positioning is a simple motor task, one of a very few, in which the intertrial correlations do not ordinarily show strong superdiagonal patterning. However, if knowledge of results (KR) is withheld, superdiagonal pattern appears. If KR is given every 3rd, 4th, or 10th trial, superdiagonal pattern appears in blocks of trials without KR. The pattern is strongest in the first block of trials without KR and in gradually weakening strength in subsequent blocks. It appears, therefore, that in lever-positioning an inverse relation holds between learning and superdiagonal pattern. In proportion as learning progresses (because KR is given) superdiagonal pattern degenerates. When KR is given after every trial, the pattern is vestigial at best. These results are attributed to the terminal effects of practice in a very simple task.