Learning conditional frequencies in a probability learning task

The study was prompted by a theoretical discussion of probability learning by Estes (1976). In three separate experiments, subjects were presented with frequency information in the form of wins and losses among 3 teams, and later predicted future wins and losses. Frequencies were devised so that conditional win frequencies for a pair of teams were either inconsistent or consistent with marginal win frequencies for each team. In experiment 1, when subjects predicted future events on the basis of known past frequencies, predictions were generally based on conditional frequencies. In experiment 2 six blocks of observations were presented, with predictions following each block. What little learning did occur was in the direction of the conditional frequencies. Subjects in experiment 3 were able to learn conditional frequencies when given explicit instructions to do so. Results were discussed in terms of a two-stage hypothesis generation model that might operate within the framework of an associative theory of probability learning.     

On construct validity: A critique of Miniard and Cohen's paper

Miniard and Cohen's conclusion that our measures of attitudes and subjective norms lack construct validity is rejected. It is shown that the data from their study are entirely consistent with data from previous investigations and that the data provide additional evidence for the predictive validity of our theory and for the construct validity of our operations.     

The effects of consensus requirements and multiple decisions on mock juror verdict preferences

After watching a simulated rape trial, prerecorded on videotape, mock jurors either did or did not expect to sentence a defendant following deliberation with or without a group verdict required. Both sentencing expectation and verdict requirement significantly elevated jurors' preference for conviction (and average ratings of guilt likelihood). Closer analyses of personal changes (before and after deliberation) in the distribution of opinions suggested that majorities favoring not guilty were more influential than guilty-favoring majorities; and, somewhat unexpectedly, minorities in juries which deliberated without a verdict required were more likely to change personal opinions than minorities in juries required to render a verdict. The overall social decision scheme confirmed earlier observations about the importance of the initial majority in determining the verdict; but the majority did not always prevail and there was a marked asymmetry (“defendant protection”) in its action.     

Disfluent speech associated with brain damage

The frequency and type of disfluencies in the spontaneous speech of 15 people with Broca's aphasia and right hemiplegia was studied. Two aged-matched control groups (15 nonaphasic stroke patients with left hemiplegia and 15 normals) were also studied. The frequency of disfluencies in the speech of aphasics was three times greater than that in the speech of either control group. However, most of the disfluencies uttered by aphasics were of the types commonly found in speech of normals.     

Crossed aphasia: analysis of four cases

Data from the Rehabilitation Institute of Chicago was used to contrast a sample of 358 aphasics with data from a Boston aphasia and aging study (L. Obler, M. Albert, H. Goodglass, and F. Benson, Brain and Language, 6, 318–322, 1978). Unlike the females, Chicago males showed remarkable similarity to the Boston male sample for the Broca, Wernicke, and Global groups with ratios of approximately four Broca's to every two Wernicke's and Global aphasics. Similar to the Boston Sample, Wernicke's aphasics were 11.6 years older (p < .001) than Broca's aphasics.     

Increasing achievement motivation and work productivity in a chronic psychiatric population

The major goal of this study was to determine if social reinforcement for behavior in a simulated work activity would increase achievement motivation, work interest, and simulated work activity production. Forty-five chronic psychiatric patients were randomly assigned to one of three groups: work sample with praise, work sample without praise, and a no-treatment control group. A 3 (between) × 2 (within) analysis of variance was run for each dependent measure, that is, achievement imagery, work interests, and simulated work production. The main effect for the interaction between trials and treatment was significant on each dependent measure. Follow-up Duncan Multiple Range Tests indicated that the praise group showed a significant improvement on each dependent measure, pre to post, as well as significantly greater improvement than the no-treatment control group and/or the work sample without praise group. These results are discussed in terms of the procedure used as a method for increasing motivation and in terms of possible generalization of results to other treatment situations.