Circular vection as a function of the relative sizes, distances, and positions of two competing visual displays

In studies where it is reported that illusory self-rotation (circular vection) is induced more by peripheral displays than by central displays, eccentricity may have been confounded with perceived relative distance and area. Experiments are reported in which the direction and magnitude of vection induced by a central display in the presence of a surround display were measured. The displays varied in relative distance and area and were presented in isolation, with one moving and one stationary display, or with both moving in opposite directions. A more distant display had more influence over vection than a near display. A central display induced vection if seen in isolation or through a 'window' in a stationary surrounding display. Motion of a more distant central display weakened vection induced by a nearer surrounding display moving the other way. When the two displays had the same area their effects almost cancelled. A moving central display nearer than a textured stationary surround produced vection in the same direction as the moving stimulus. This phenomenon is termed 'contrast-motion vecton' because it is probably due to illusory motion of the surround induced by motion of the centre. Unequivocal statements about the dominance of an eccentric display over a central display cannot be made without considering the relative distances and sizes of the displays and the motion contrast between them.     

Induced motion: isolation and dissociation of egocentric and vection-entrained components.

Induced motion (IM) is illusory motion of a stationary test target opposite to the direction of the real motion of the inducing stimulus. We define egocentric IM as an apparent motion of the test target relative to the observer, and vection-entrained IM as an apparent motion of a stationary object along with an apparent motion of the self (vection) induced by the same stimulus. These two forms of IM are often confounded, and tests for distinguishing between them have not been devised. We have devised such tests. Our test for egocentric IM relies on evidence that this form of IM is due mainly to a misregistration of eye movements when optokinetic nystagmus (OKN) is inhibited, and on evidence that OKN is evoked only by stimuli in the plane of convergence. Our test for vection-entrained IM relies on evidence that vection is evoked only by the more distant of two superimposed inducing stimuli. Thus we found egocentric IM to be induced without vection or vection-entrained IM when subjects converged on a foreground moving display with a stationary display in the background, and vection-entrained IM to be induced without egocentric IM when subjects converged on a stationary-foreground display with a moving display in the background. The two types of IM were evoked in opposite directions at the same time when subjects converged on a foreground moving display while a background display moved in the opposite direction. The two forms of IM showed no signs of interaction, and we conclude that they rely on independent motion mechanisms that operate within distinct frames of reference. A control experiment suggested that the depth adjacency effect in IM is determined by the depth adjacency of the inducing stimulus to convergence, not just to the test target.     

Serial pattern learning by event observation.

Serial pattern learning was investigated in a variation of the task introduced by Nissen and Bullemer (1987). We presented an asterisk at 1 of 4 spatial locations on each trial, and Ss either responded with a keypress or observed the event. The first 4 blocks contained 10 repetitions of a 10- or 16-element pattern, and the 5th block contained a random sequence. The difference in response time on the 5th random block and the previous patterned block served as an indirect measure of pattern learning. A direct measure was obtained in a final test block in which Ss predicted the next asterisk position. Equivalent learning occurred for responding and observing with indirect measures, but observation was superior with direct measures. These findings indicate that knowledge of serial order can develop through simple perceptual experience, and this is more available to deliberate recall than is knowledge acquired while responding.     

“Snips and snails and puppy dog tails”: Gender of agent,recipient, and observer as determinants of perceptions of discipline

This study examined the role of gender of observer, parent, and child on judgments of the severity, appropriateness, and consequences of various forms of discipline. Young adults read stories describing a disciplinary encounter between parent and child and made required judgments. Consistent gender differences emerged. Females judged the discipline more harshly than males, rating it as more severe, more abusive, less appropriate, and more likely to result in emotional harm. Discipline of daughters was judged to be harsher than identical treatment of sons, particularly when the discipline was administered by the father. The implications of differential judgments are discussed.     

Factors associated with juvenile detention truancy

Factors influencing truancy from a juvenile court treatment facility were investigated. Youth born in 1962 (N = 124) who were placed in the facility were compared for number of truancies, background, and personality variables. Results showed that males with prior adjudication for home or school truancy had a 65% probability of eloping from the court facility as compared to a 34% probability for youth adjudicated for other offenses. Most females were adjudicated for truancy offenses and showed a 62% probability of truancy while in the court facility. Further, for females who eloped and were returned, the probability of a subsequent truancy was above 80%. Personality characteristics of truants varied with sex: male truants were more likely to be conduct disordered youth for which impulsivity and disregard for social norms is prevalent; female truants appear more likely to be in conflict over autonomy issues.     

Inhibition of return in a selective reaching task: an investigation of reference frames.

Most previous studies of inhibition of return (IOR) have examined reaction time (RT) and accuracy. These effects have been observed via saccades to targets or with key-press responses. In this study the authors examined, for the first time, IOR in components of a selective reaching task in which participants directly reached for and depressed target keys. When the interval between cue and target was 600 ms, robust IOR effects were observed in RT to begin the reach, but no effects were observed in the movement components (movement time to complete the reach and the path of the reach). However, when the cue-target interval was short (200 ms), hand paths deviated toward the cue. The results suggest that although RT measures of IOR appear to reveal perceptual rather than action-based processes, action-based representations may be briefly activated by irrelevant cues, which can be observed via analysis of three-dimensional reach path.