Adaptation in the constancy of visual direction measured by a one-trial method

Adaptation to field displacement during head movements in the direction with the head rotation and in the direction against it was produced under otherwise identical conditions and compared; the field displacement rate was also varied. A rapid training procedure was used, and a novel one-trial test was employed that could measure the adaptation well enough to compare the effects of various training conditions. The one-trial test measured the magnitude of one of the manifestations of adaptation, the apparent displacement of a stationary target during head movements. This apparent horizontal target displacement was transformed into an oblique one by having the head movements that brought forth the apparent target displacement simultaneously cause an objective vertical target displacement. The slant of the resultant apparent motion path varied with the magnitude of the apparent horizontal target displacement. It was measured by having S reproduce its slant angle. It was found that adaptation to field displacement in the direction with the head rotation was consistently greater than adaptation to the opposite displacement conditions. An explanation for this result is offered.     

The effect of abnormal displacement of the retinal image during eye movements

The displacement of the images on the retina that results from a turning of the eye does not lead to an apparent motion of what is seen, It has been generally assumed that this is due to a compensating process which takes eye movement into account and serves to discount those image displacements that result from eye movements, It follows from this view that an abnormal image displacement, that is, an image displacement that is larger or smaller than the causing eye movement would warrant, should lead to an experienced displacement of the target. Abnormal image displacement was produced by placing the eye in the converging or diverging bundle of rays from a point source that form behind a strong positive lens; this arrangement yielded a disc-shaped image, the projection of the pupil onto the retina, which displaced abnormally during eye movements. By changing the position of the eye along the axis of the lens in relation to the crossing point of the bundle, the degree to which the displacement was abnormal could be varied, For various displacement rates ranging from 25% to 120 and 400% of normal, abnormal displacements produced by incidental eye movements remained unnoticed, Only where eye movements were intentional did some of our Ss report shifts of the perceived image. It is suggested that the organism copes with the image displacement resulting from the ever-present incidental eye movements not by compensation but by ignoring them.     

Evaluation of visual display surfaces by real users early in the design stage

Groups of non-computer scientists were tested to evaluate the potential of an as yet non-existent interactive terminal with a screen diagonal of one meter. A simulated large image terminal provided limited realistic interactions using software developed to give close proximity to the predicted visual effect. Subjective responses from 101 subjects were elicited from a questionnaire designed to evaluate specific aspects of the “terminal” in use. From this data, two types of screen (lenticular and plain) and two types of interaction devices (touch and remote pointer) were analyzed experimentally using a two-way factorial design. Potential end-users provided positive feedback concerning future use of the Large Image Terminal. Building a realistic mock-up revealed screen contaminations which would not have been discovered until a much later stage. Although statistical analysis of screen evaluations was equivocal, the questionnaire was sufficiently penetrating to separate the positive and negative features. This methodology was invaluable in guiding the design process. Copies of the questionnaire may be obtained from the authors at the Heriot-Watt address.     

Assisting At-Risk College Students With Attributional Retraining and Effective Teaching1

Attributional retraining appears to be an effective remedial intervention for college students. However, the potential moderating effects of student and classroom characteristics have not yet been investigated systematically. In two studies, attributional retraining was provided to low- and high-risk students, followed by a videotaped lecture presented by either an ineffective or effective instructor. Attributional retraining enhanced achievement on a lecture-based achievement test only when combined with effective teaching, improving the achievement of students who had previously performed poorly (Experiment l), and of low-achieving externals (Experiment 2). The intervention provided no advantage for previously successful students and low-achieving internals. Moreover, attributional retraining induced a more internal attribution profile in students with an external locus, and increased expectations of future success in both externals and internals, but again only when students also received effective instruction. These results suggest that contextual factors related to the classroom, such as quality of instruction, and individual differences have to be considered when developing attributional retraining programs.     

An extension of the concept of specific objectivity

Comparisons of subjects are specifically objective if they do not depend on the items involved. Such comparisons are not restricted to the 1-parameter logistic latent trait model, but may also be defined within ordinal independence models and even within the 2-parameter logistic model.     

How valid is the psychoticism scale? A comment on the Van Kampen critique

Van Kampen (1993) has published a paper in which he criticizes the concept of psychoticism and the use of the P scale as a measuring device, and advances measures for his own S scale and its validity. This reply attempts to clarify the notion of ‘validity’, and to demonstrate that there is a considerable body of experimental evidence to show that P has a high degree of construct validity, whereas the Van Kampen S scale lacks completely any degree of construct validity. Several examples are given of how the experimental evidence legitimates both the P scale, and the theory (nomological network) on which it is based.     

Optimism and coping as determinants of psychosocial adjustment to rheumatoid arthritis

Psychosocial adjustment in 66 patients with chronic rheumatoid arthritis, with a mean duration of 12 years with the disease, were evaluated in a prospective design, with 62% of the sample followed up 16 months later. It was predicted that dispositional optimism would predict adjustment over time and that perceived support and perceived control would be related to psychosocial adjustment at the time of concurrent measurement. At Time 1, psychosocial adjustment was associated with greater optimism and perceived support and less disability. Optimism at Time 1 was the only significant predictor of changes in adjustment at Time 2 controlling for Time 1 adjustment and Time 2 disability. It was found that optimism temporally precedes increases in psychosocial adjustment. In terms of coping strategies, wishful thinking was related to poorer social adjustment, whereas problem-focused coping was marginally related to positive adjustment. Neither coping strategy predicted adjustment across time. Optimism at Time 1 did predict problem-focused coping at Time 2. Perceived social support regarding a specific circumstance at a given point in time enables one to persist in solving a task. Interventions to enhance the quality of life of individuals coping with progressive deteriorative disease must look at the influence of their behavior and attitude on those who provide care for them.     

Sparing and recovery of function in spinal larval frogs (Rana catesbeiana): effect of level of transection.

Bullfrog tadpoles with cervical or midthoracic transection of the spinal cord were allowed to recover for 5 weeks, at which time axonal growth across the transection site was assessed by transport of horseradish peroxidase. Weekly behavioral tests included those for posture, spontaneous locomotion, cutaneously elicited swimming, and intersegmental coordination. Behavioral and electrophysiological assessments suggest that behavioral recovery depends, at least in part, on the growth of fibers across the transection site. Anatomical and behavioral recovery does not appear to differ with the level of spinal transection, but there was greater sparing of posture, spontaneous locomotion, and stimulus-induced locomotion in tadpoles with thoracic transection of the spinal cords.