Influences of the experienced outcome density on the probability-of-responding effect in active contingency tasks

Abstract

The present study investigated the influences of experienced outcome density on the P(R) (probability of responding) effect in active contingency tasks. The P(R) effect was explained by assuming that the coincidental experiences of active responses and uncontrollable outcomes would increase the participants' cognitive contingency of the response and uncontrollable outcome. The P(R) effect has been demonstrated by only one other study so far, involving only one value of outcome density that participants experienced in the learning phase. Accordingly, the present study reexamined the P(R) effect by using three values of outcome density: 76%, 24% (Experiment 1), and 10% (Experiment 2). The results showed that the P(R) effect increased in the 76% outcome-density condition, but did not in the other conditions. The results imply that the P(R) effect would increase only when one experiences the high outcome density.