Contiguity and the outcome density bias in action-outcome contingency judgements. 
In cause-outcome contingency judgement tasks, judgements often reflect the actual contingency but are also influenced by the overall probability of the outcome, P(O).  Action-outcome instrumental learning tasks can foster a pattern in which judgements of positive contingencies become less positive as P(O) increases.  Variable contiguity between the action and the outcome may produce this bias.  Experiment 1 recorded judgements of positive contingencies that were largely uninfluenced by P(O) using an immediate contiguity procedure.  Experiment 2 directly compared variable versus constant contiguity.  The predicted interaction between contiguity and P(O) was observed for positive contingencies.  These results stress the sensitivity of the causal learning mechanism to temporal contiguity.