The representation of nonuniform motion: induced movement

Induced motion occurs when there is a misallocation of nonuniform motion. Theories of induced motion are reviewed with respect to the model for uniform motion recently proposed by Swanston, Wade, and Day. Theories based on single processes operating at one of the retinocentric, orbitocentric, egocentric, or geocentric levels are not able to account for all aspects of the phenomenon. It is therefore suggested that induced motion is a consequence of combining two different types of motion signals: one provides information by registering the motion with respect to the retina, orbit, and egocentre; the other provides information only on the relational motions between the pattern elements. Simple rules are given for defining a frame of reference for the relational motion process, which can result in a reallocation of the motion signals. It is proposed that the two signals in combination are weighted differentially, with the greater influence coming from the relational signals. Procedures for determining the weighting factors are described, and predictions from the model are examined.     

The perception of continuous curves in dot stimuli

Two categorisation experiments are reported in which the perceptual phenomenon that some simple arrays of discrete dots appear as a continuous curve whereas others are perceived as an angular contour or as consisting of separate groups of dots was investigated. Triplets of dots were presented in the first experiment, and complete or incomplete regular dot polygons (ie dots positioned on the vertices of imaginary regular polygons) in the second. In both experiments the perception of a curve versus an angle was determined mainly by the relative orientations of the dots, ie by the angles between successive virtual lines, whereas the lengths of the virtual lines had relatively little influence. In experiment 2 the number of displayed dots was shown to be a second independent factor for perceiving continuity. These results are in agreement with results from experiments on dipole textures discrimination, and suggest the psychological existence and importance of virtual lines in the visual processing of dot stimuli.     

Individual differences and measures of aggression in laboratory studies

After inducing hostility toward a confederate by threatening subjects' self-esteem, subjects were then given the opportunity either to deliver shocks (Experiment 1) or to withhold rewards (Experiment 2) from their confederate. Physiological measures were taken prior to the hostility induction, shortly after the induction and, finally, after the opportunity to aggress. Measures of individual differences relating to aggressive behavior were also considered. While the experimental manipulation was the best predictor in the ‘withholding rewards’ condition, measures of dissipation-rumination tendencies and emotional vulnerability were the best predictors in the ‘shock administration’ condition. In both conditions, systolic blood pressure seemed to reflect differences in arousal as a function of the hostility induction procedure, while subjects in the withhold rewards procedure also showed a decrease in systolic pressure after having an opportunity to aggress toward the confederate. It was concluded that not only is the withholding of rewards a more ethically acceptable procedure than shock administration, but it is also more likely to reflect experimental rather than individual difference affects.     

Difficulty and familiarity norms for 192 single-solution word fragments

Normative data are presented for the probability of successfully completing 192 single-solution word fragments. Normative data on the familiarity of college students with the solution words are also given, along with estimates of word frequency from existing norms. Regression analyses were performed in order to predict fragment completion difficulty from familiarity, frequency, and several structural characteristics of the fragments. Familiarity, whether or not first and/or last letters appeared in the fragment, and the ratio of letters to missing letters in the fragment were included in the regression equation as significant predictors of difficulty for this fragment set.     

Learning and motivation: Computer simulations of the Rescorla-Wagner,Solomon-Corbit,and Schull models

A suite of programs is described for simulating the Rescorla-Wagner (1972) model of associative learning, the Solomon and Corbit (1974) opponent-process theory, and Schull’s (1979) extension of the latter. The programs are written for the Commodore 64 computer.     

Parent-child communication about sex and young adolescents' sexual knowledge and attitudes

Previous studies indicate that adolescents whose parents talk to them about sex tend to be less sexually active and more likely to use an effective means of contraception. This study sought to determine the relationship between parent-child communication about sex and young adolescents' reproductive and contraceptive knowledge and sexual attitudes. Twenty-two 12- to 14-year-olds and their parents completed sexual-knowledge, sexual-attitude, and contraceptive-choice questionnaires. Families were divided into high-communication and low-communication groups. There were no significant differences in the sexual knowledge, attitudes, or contraceptive choices of the children in the two groups, but the correlation between parents' and children's sexual attitudes in the high-communication group was significantly higher than that of the low-communication group. Although this was a correlational study, it seems likely that the similarity in sexual values was the result of parent-child discussion about sex.     

Biofeedback, cognitive training and relaxation techniques as multimodal adjunct therapy for hospitalized adolescents: a pilot study

Modifications and adjuncts to traditional therapy techniques appear to be necessary for successfully treating hospitalized adolescents with impaired social and verbal skills, and a history of acting-out behavior. Modified therapy groups were combined with a structured biofeedback and cognitive training program to help these adolescents control anger and modify their behavior. Used in conjunction with training and practice in relaxation techniques, this multimodal treatment approach appeared to be helpful in both reducing incidents of acting out on residential units, and in reaching individualized therapeutic goals. The present paper describes use of this multimodal approach within selected residential settings, and outlines the structured materials developed by the authors.