The constancy of object orientation: Compensation for ocular rotation

When a thin horizontal line is displaced, either left or right of straight ahead, or when a vertical line is displaced up or down, systematic changes occur in the binocular disparity associated with the target. In threeexperiments, Ss matched the orientation of displaced targets with a variable comparison line. Estimates of apparent displacement with a pointing technique were also made. Since head position was fixed, apparent displacement was mediated by the angle of ocular rotation. Near perfect matches were made with vertical targets, but horizontal targets produced errors suggestive of underestimation of apparent displacement. However, the pointing data did not yield clear evidence for this view. Control data denien the possible role of the induced effect (IE) in matching the horizontal targets, and the result were discussed in the context of orientation constancy based upon compensation for displacement.     

Perceptual aftereffects of sustained convergence

Attention, Perception, & Psychophysics - Fixating a target for 6 or 8 min was shown to produce distance aftereffects that varied in direction (i.e., over- or underestimation) and magnitude as a...     

Further evidence for an orientation constancy based upon registration of ocular position

Summary In four experiments Ss were exposed to wedge prisms or maintained an asymmetrical eye and head posture in order to induce a shift in the apparent direction of gaze. Systematic changes in the apparent orientation of a line target were obtained as inferred from an assumed algorithm relating optical input and registered direction of gaze.This research was supported by Grant MH13006 from the National Institute of Mental Health to the first author.The aid of Ms. Janine Pyrek and Ms. Lynne Shebilske is gratefully acknowledged.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

Distance perception for points at equiconvergence and equidistance loci

Subjects viewed luminescent targets placed at an equidistance (ED) locus or on a comparable equiconvergence locus, the Vieth-Müller circle (VMC). In darkness, subjects moved the index finger to the apparent distance of the visible target. This was repeated at leftward eccentricities of 0 degrees (straight ahead), 15 degrees, 22.5 degrees, 30 degrees, 37.5 degrees, and 45 degrees. Contrary to theoretical expectations, apparent distance to points on the VMC did not describe an equidistance locus, but diminished significantly with increasing eccentricity, whereas ED settings increased slightly but significantly. Binocular and monocular groups performed equivalently. Veridicality of results appears to be the outcome of an accommodation-convergence conflict with a dominant role for accommodation.     

Psychological skills and mindfulness training effects on the psychological wellbeing of undergraduate music students: An exploratory study

This study explored the efficacy of psychological skills and mindfulness training intervention on the psychological wellbeing of undergraduate music students. Participants were undergraduate music students (n = 36) from the Department of Music at a South African university, 21 of whom were elected to take the psychological skills and mindfulness training intervention. Data on their self-reported psychological wellbeing, psychological skills, mindfulness and performance anxiety levels were collected pre-and post-intervention. The analysis applied non-parametric procedures to determine changes in students’ psychological wellbeing after the seven-week intervention programme. Findings suggest improvements in psychological wellbeing, psychological skills, mindfulness and performance anxiety with training. Psychological skills and mindfulness training may have benefits to the psychological wellbeing of music students.