Rating Causal Relations: Role of Probability in Judgments of Response-Outcome Contingency

We investigated the possible role of the conditional probabilities of an outcome given a response P(O|R) and of an outcome given the absence of a response P(O|NoR) in mediating college students' judgments of response-outcome contingency. A total of 150 subjects in three experiments was asked to describe the effect that telegraph key tapping had on the brief illumination of a lamp. Subjects' ratings along a prevent-cause scale closely approximated the scheduled contingencies between response (R = key tap) and outcome (O = lamp illumination), as measured by the delta coefficient ΔP = P(O|R) − P(O|NoR) (Experiments 1 and 3). Subjects also sensitively rated the conditional probabilities of an outcome when they tapped the key and when they refrained from doing so (Experiments 2 and 3). Nevertheless, the evidence failed to support the hypothesis that causal ratings were mediated by subjective judgments of P(O|R) and P(O|NoR) because the errors made in judging the conditional probabilities were not consistent with the errors made judging ΔP. We suggest that an associative explanation derived from a model devised by R. A. Rescorla and A. R. Wagner (1972) might account for these and other results.