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.     

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.     

Remembering left-right orientation of pictures

In a study of recognition memory for pictures, we observed an asymmetry in classifying test items as "same" versus "different" in left-right orientation: Identical copies of previously viewed items were classified more accurately than left-right reversals of those items. Response bias could not explain this asymmetry, and, moreover, correct "same" and "different" classifications were independently manipulable: Whereas repetition of input pictures (one vs. two presentations) affected primarily correct "same" classifications, retention interval (3 hr vs. 1 week) affected primarily correct "different" classifications. In addition, repetition but not retention interval affected judgments that previously seen pictures (both identical and reversed) were "old". These and additional findings supported a dual-process hypothesis that links "same" classifications to high familiarity, and "different" classifications to conscious sampling of images of previously viewed pictures.     

Multiple regression analysis of twin and sibling data

DeFries and Fulker (1985) employed a multiple regression analysis of twin data in which a cotwin's score is predicted from the proband's score, the coefficient of relationship (R = 1.0 for monozygotic twins and 0.5 for dizygotic twins), and their interaction to yield direct estimates of heritability (h²) and the proportion of variance due to common or shared environmental influences (c²). The purpose of the report is to extend this model to allow for the analysis of data from more than two familial relationships simultaneously. Data from identical twins, fraternal twins, and siblings pairs, in which one member of each pair was selected based on low reading performance, were analyzed. To analyze the data simultaneously, additional coefficients were added to the regression equation in order to differentiate shared environmental influences of twins and siblings. When the model was applied to the combined cognitive data, significant estimates for heritability were obtained in three of the six tests analyzed. The results also indicated a lack of justification for the separate twin and sibling environmental parameters, and a discussion of more parsimonious models is included.     

Repeated exposure and the attractiveness of synthetic speech: An inverted-U relationship

Previous experimental investigation of the effects of repeating an unfamiliar stimulus suggests that mere exposure breeds attraction (e.g., Zajonc, 1968). On the other hand, correlational work with naturally occurring stimuli such as names, music, or landscapes suggests that there is also an overexposure effect: the preference function does rise with familiarity at first but then reaches a turning point and diminishes. The study (N=72) demonstrates this inverted-U relationship in an experimental setting. The stimuli were synthetic nonsense speech, permitting exact control of exposure durations and interstimulus intervals. The critical factors for demonstrating the effect are probably (1) the inclusion of a large number of repetitions, and (2) blocked repetition of each stimulus in a homogeneous sequence not interspersed with other more or less frequent stimuli.     

Teaching social skills to emotionally disturbed adolescent inpatients

A social skills training program was evaluated with emotionally disturbed adolescent inpatients. The targeted social skills required an action or reaction within six skill areas. The program was adapted from a commercially available social skills training game that features the use of response specific feedback, self-monitoring, individualized reinforcers, and individualized performance criteria. A peer conducted the baseline and posttraining sessions while the training was conducted by an adult who had no previous interactive history with the subjects. A multiple baseline design across groups demonstrated that the program increased appropriate responding in all skill areas and that these effects generalized during the posttraining peer conducted sessions. A generalization test indicated that the subjects used their newly learned skills with a novel adult outside the training setting. The program appears quite applicable to emotionally disturbed adolescents since it targets skills in a variety of areas and employs standardized procedures to enhance replicability.     

A brainstem “mini-discharge” syndrome (anesthesia dolorosa)

Chronic pain consisting of anesthesia dolorosa secondary to bilateral interruption of the trigeminal nerves is presented as a brain stem reticular denervation syndrome. Electrothalamograms revealed fast frequency discharges in the mesothalamic prerubral and centermedian reticular formation. Mesothalamic electrical stimulation attenuated the discharges. Pain and other symptoms presumably of brainstem origin also were attenuated or abolished by therapeutic electrical stimulation twice daily. It is postulated that brain stem-represented behavioral generators are implicated by the reticular discharges in order to produce the complex symptomatology. Consequently the symptom complex is collectively identified as a brainstem “mini-discharge” syndrome. A theoretical discussion is presented to defend the thesis that reticular denervation-induced low threshold discharge system accounts for the episodic states of pain, dyskinesia, mood, and memory disturbances.