David A. Summers

Negative effects of outcome-feedback in multiple-cue probability learning☆

Abstract Performance in a probabilistic learning task was studied under conditions in which learners received (1) knowledge of results after every trial (outcome-feedback), (2) information about task properties, and (3) both outcome-feedback and information about task properties. Outcome-feedback was not only unnecessary for improved performance, but was found to impede performance as well.

Subjective vs objective description of judgment policy

Subjective descriptions of judgment policy were compared with the descriptions afforded by an objective regression model. It was found that (1) Ss reported using more cues than were indicated by the model, (2) the subjective weights reproduced Ss’ judgments with substantially less accuracy than did the objective regression weights, and (3) Ss communicated the function (linear vs nonlinear) characterizing their policies with better-than-chance accuracy.

A note on intuitive vs analytic thinking

Abstract Brunswiks propositions concerning intuitive vs analytic thinking were investigated by assessing performance in a three-cue inference task presented in one of three ways. In the first condition, cues were presented only as points on a blank, two-dimensional field, thus encouraging an intuitive, or perceptual, mode of thinking. In the second condition, subjects were given only the numerical equivalents of the three cues. Finally, in the third condition, the cues were presented both perceptually and numerically. The resulting error distributions were consistent with Brunswiks theoretical propositions.

Multiple probability-learning with shifting weights of cues.

Mans adjustment to an uncertain environment has been thoroughly studied in the classical experiment on probability-learning, in which the stimulus-situation is characterized by some degree of randomness but is stationary through trials. Uncertainty is associated with the event that occurs on any specific trial, but the probability of which event will occur remains constant over trials.1 Many uncertain situations in the real world are not only partially random, but are also nonstationary. Characteristics of such situations are not stable but change over time. A deviation at any time may be either a random fluctuation or the reflection of a genuine change in the situation. Adjustment to a nonstationary, uncertain environment requires that S detect whether a deviant event is a random fluctuation or the signal of a real change. Responses should ignore random fluctuations, but should react to genuine changes. In the classical experiment on probability-learning, the probability of response stabilizes at, or somewhat above, the stationary probability of the corresponding event. When the probability of an event shifts as a function of trials, a corresponding shift occurs in the probability of the response.2 The present experiment is in the context of multiple probability-learning. Whereas previous experiments have compared the degree to which cue-weights (dependence upon cues) for responses correspond with

A note on nonprofessional judgments of mental health.

Ninety Ss who had either not received or not completed formal diagnostic training made mental health judgments about 60 hypothetical persons, each of whom was represented on a 7-cue behavior profile. A comparison of these judgments with those made by 24 clinical psychologists and psychiatrists failed to reveal a significant difference between groups in terms of scope of cue utilization, magnitude of judgments, or confidence. Differences between groups were obtained, however, in terms of judgment reliability and profile cue utilization. Notable in regard to the latter was the finding that nonprofessional Ss usually ignored information of a “positive” nature (“enthusiasm”), and tended to weight heavily information about violations of legal norms.

The effects of influence conditions and discrepancy upon authoritarian conformity

Having made a series of numerosity judgments, Ss were exposed to judgments presumably made by three other individuals. The discrepancy between Ss’ judgments and those attributed to the others was either small or large and was revealed under conditions that emphasized either group or individual accuracy. When the discrepancy was large, nonauthoritarian Ss changed their judgments in both influence conditions, while the authoritarian Ss showed substantial change only in the group accuracy condition. When the discrepancy was small, no differences between authoritarian and nonauthoritarian conformity were observed.