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When two jointly presented cues predict different outcomes, people respond faster to the conjunction/overlap of outcomes. Two explanations exist. In the joint account, people prioritize conjunction. In the serial account, people process cues serially and incidentally respond faster to conjunction. We tested these accounts in three experiments using novel web based attention-tracking tools. Participants learned colour-location associations where colorus predicted target locations (Experiment 1). Afterward, two cues appeared jointly and targets followed randomly. Exploratory data showed participants initially prioritized locations consistent with the conjunction, shifting later. Experiment 2 presented complex color-category associations during exposure. Upon seeing joint cues, participants' responses indicated both serial and joint processing. Experiment 3, with imperfect cue-outcome associations during exposure, surprisingly showed robust conjunctive predictions, likely because people expected exceptions to their predictions. Overall, strong learning led to spontaneous conjunctive predictions, but there were quick shifts to alternatives like serial processing when people were not expecting exceptions. [ABSTRACT FROM AUTHOR]

Given a prior distribution over a finite outcome space, how is the distribution updated when one outcome is excluded (i.e., assigned probability 0)? We describe two experiments in which estimated probabilities seem to “stick” to salient events. The probabilities of such events remain relatively invariant through updating. Our results suggest that the credence assigned to a salient category is sometimes more basic than the credence assigned to the constituents that comprise the category. [ABSTRACT FROM PUBLISHER]

Abstract: Bayesian orthodoxy posits a tight relationship between conditional probability and updating. Namely, the probability of an event A after learning B should equal the conditional probability of A given B prior to learning B. We examine whether ordinary judgment conforms to the orthodox view. In three experiments we found substantial differences between the conditional probability of an event A supposing an event B compared to the probability of A after having learned B. Specifically, supposing B appears to have less impact on the credibility of A than learning that B is true. [Copyright &y& Elsevier]

Jeffrey (1983) proposed a generalisation of conditioning as a means of updating probability distributions when new evidence drives no event to certainty. His rule requires the stability of certain conditional probabilities through time. We tested this assumption ('invariance') from the psychological point of view. In Experiment 1 participants offered probability estimates for events in Jeffrey's candlelight example. Two further scenarios were investigated in Experiment 2, one in which invariance seems justified, the other in which it does not. Results were in rough conformity to Jeffrey's (1983) principle. [ABSTRACT FROM AUTHOR]

Abstract: In standard treatments of probability, is defined as the ratio of to , provided that . This account of conditional probability suggests a psychological question, namely, whether estimates of arise in the mind via implicit calculation of . We tested this hypothesis (Experiment 1) by presenting brief visual scenes composed of forms, and collecting estimates of relevant probabilities. Direct estimates of conditional probability were not well predicted by . Direct estimates were also closer to the objective probabilities defined by the stimuli, compared to estimates computed from the foregoing ratio. The hypothesis that arises from the ratio fared better (Experiment 2). In a third experiment, the same hypotheses were evaluated in the context of subjective estimates of the chance of future events. [Copyright &y& Elsevier]