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Biomedical subjects

W L Shebilske

Publications and source records attributed to W L Shebilske.

14 recordsLinked to original sources
PubMed1997

Competition and performance on a computer-based complex perceptual-motor task.

Employees of temporary agencies practiced Space Fortress, a complex video game task, for 10 sessions, each consisting of 8 practice and 2 test games of 3 min each. Trainees practiced individually, in dyads, or in tetrads, and they were classified as having high or low aptitude based on computer attitude scores and baseline performance. Competition for monetary prizes was introduced early in training, late in training, or not at all. Competition facilitated high-aptitude trainees but not low-aptitude trainees. Group size and the timing of competition instructions had no main effects or interactions. The results are discussed in terms of social facilitation theory, according to which competition facilitates dominant responses, which helps high-skill trainees but not low-skill trainees.

Adolescent↗
PubMed1996

Effectiveness of individual and dyadic training protocols: the influence of trainee interaction anxiety.

The present study focuses on the consequences of the social dynamics that are created whenever two or more individuals are brought together for the purpose of training. An investigation of the role of individual differences in interaction anxiety on training outcomes demonstrated that the comparative effectiveness of dyadic versus individual protocols for computer-based training is moderate by trainees' level of interaction anxiety. Specifically, assignment to a dyadic protocol adversely affected the performance of high-interaction-anxiety participants but appeared to be advantageous for low-interaction-anxiety participants. Implications are discussed for changing the design and implementation of computer-based protocols for training groups and individuals in military and industrial training centers.

Adult↗
PubMed1991

The perception and metaperception of architectural designs communicated by video-computer imaging.

Non-architects answered multiple-choice questions about depth, size, shape, texture, and conformation in exterior building scenes presented by manual rendering or video-computer techniques including a single viewpoint, multiple viewpoints, and animation. They also rated (a) confidence in their answers, (b) overall judgments of clarity, and (c) overall impressions of realism. The viewing time needed for judgments was also measured. Presentation technique did not affect the viewing time, but it did affect perceptual accuracy and ratings of confidence, clarity, and realism. Animation yielded higher ratings in all categories. It also produced the highest accuracy for depth perception, but the lowest accuracy for size and texture perception. The low accuracy for size and texture was exacerbated by high confidence in the wrong answers. Multiple viewpoints caused neither false confidence nor reduced accuracy in any category, and yielded the highest accuracy in two categories: size and texture. The combined effects on perception and metaperception (knowledge about one's own perceptual processes) suggest that animation creates the best overall impression and is the best for conveying depth information. However, multiple viewpoints are better than animation for conveying size and texture information. These results are discussed with respect to theories of perceptual representation.

Adult↗
PubMed1991

Phoria, Hering's laws, and monocular perception of direction.

By recording eye movements while subjects fixated a stationary stimulus and reported on its apparent position, four experiments tested whether Hering's laws of visual direction describe monocular perception of egocentric direction. Experiments 1, 2, and 3 alternately covered each eye. Experiments 1 and 2 showed that the stimulus appeared to displace leftward when the left eye was occluded, and vice versa. The apparent displacement was correlated with lateral heterophoria in the occluded eye, and phoria was necessary for the illusory displacement. As a descriptive model, these results expand the range covered by Hering's laws, but they leave open several process models, including ones based on retinal image displacements without reference to extraretinal information. Experiment 4 eliminated retinal image displacements and found apparent target displacements that imply processing of extraretinal information.

Adult↗
PubMed1984

Efferent factors in natural event perception can be rationalized and verified: a reply to Turvey and Solomon.

Contrary to the view that ambient light information unequivocally specifies phenomenal events, recent research suggests that natural event perception is determined by processes that pick up and combine visual and motor information. This thesis is challenged by Turvey and Solomon (1984). The present article responds to their misgivings by elaborating empirical methods and theoretical arguments of past work. A control experiment is also presented on pointing measurements of distance illusions related to esophoric shifts of eye convergence that are induced by near work. The soundness of both the empirical methodology and the theoretical arguments in support of the original thesis is upheld.

Distance Perception↗
PubMed1983

Induced esophoric shifts in eye convergence and illusory distance in reduced and structured viewing conditions.

Two experiments measured distance judgments in reduced and structured viewing conditions before and after induced phoria. Experiment 1 induced phoria shifts with three 5-min. intervals of close handwork (i.e., needle threading) that had naturalistic characteristics of observers (a) choosing their own viewing distance, (b) moving their heads freely, and (c) viewing in a well-illuminated, structured environment. The handwork induced a 1.20-diopter esophoric shift and a 1.22-cm overestimation of distance under reduced test conditions. The handwork induced no measurable illusion under structured viewing conditions. Experiment 2 induced phoria shifts with 10 min. of fixation on a target 11 cm away. This procedure induced a 4.65-diopter esophoric shift, a 6.34-cm overestimation of distance in reduced conditions, and a 2.31-cm overestimation of distance in structured conditions. We argue that visual and motor information interact to determine perceptions and that induced esophoric shifts in everyday situations may shape the nature of that interaction.

Adaptation, Ocular↗
PubMed1981

Habituation of visual attention in infants with minor physical anomalies.

Human and geometric forms were presented to 12-month-old male infants to determine if those with a large number of minor physical anomalies would show different habituation than infants with a small number. Results from a procedure using human forms in a random order failed to yield differences, but differences in dishabituation did appear when geometric forms were presented in a standard habituation procedure, and in response decrement when subgroups were created to test for differences in infant state as a function of task demands. Slower response decrement found in high-anomaly infants tested in a low task-demand condition was consistent with Lewis's findings in infants with various forms of brain pathology.

Attention↗