On the motivational effects of positive verbal reinforcement on performance: Toward an inverted-U relationship

The purpose of this study was to ascertain the motivational effects of positive verbal reinforcement on the performance of a qualitative task. Male subjects performed on a task consisting of 24 slides that allowed them to test their decision-making abilities in simulated situations. Subjects performed under one of five noncontingent verbal reinforcement ratios (.00, .25, .50, .75, or 1.00). Subjects' accuracy and reaction times to each of the 24 slide stimuli were recorded and transformed into a total performance index. In line with an inverted-U hypothesis, it was hypothesized that if motivational effects of positive verbal reinforcement exist, they should induce a curvilinear relationship between reinforcement ratio and performance. This hypothesis was supported by the results of a trend analysis that showed that only the quadratic curvilinear term was significant. Inspection of means revealed the presence of an inverted-U curve such that performance gradually increased from ratio 0 and reached a maximum at ratio .50, following which a decrease in performance was obtained for ratios .75 and 1.00. Results support a motivational interpretation of the effects of positive verbal reinforcement on performance. Findings are discussed in light of the interaction between motivational and attentional processes.