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Biomedical subjects

G M Redding

Publications and source records attributed to G M Redding.

16 recordsLinked to original sources
PubMed1982

Mechanisms for precuing superiority in visual recognition.

Superior recognition, when similar alternatives are studied prior to brief target pictures of common objects, is usually attributed to selective feature analysis, which is beneficial only when the target is not readily discriminable in the alternatives. The present study found equal precuing superiority, however, for similar and dissimilar alternatives with abstract geometric stimuli, and with pictures of common objects, precuing superiority occurred only when each alternative represented the same semantic category. Precuing effects did not appear when different categories were represented in the alternatives, and performance was similar to other conditions in which only a categorical match between target and alternatives was possible. These results suggest that selective feature analysis and precuing superiority only occur when the target cannot be identified by its semantic category. With dissimilar alternatives activation of the target's category can be used to select a response, and there is no benefit from precuing.

Attention↗
PubMed1981

Processing line location and orientation.

For stimulus dimensions of line location and orientation with both card-sorting and discrete reaction-time trials, facilitation occurred when dimensions were positively correlated, and interference appeared when dimensions varied orthogonally. Interference could not be attributed to differential sensory accrual arising from positional uncertainty or to a repetition-effects advantage for control over orthogonal conditions. Facilitation tended to disappear when the same response was not required for the two dimensions, and when competing responses were required, interference appeared with redundant dimensions (negatively correlated stimulus sets). These data seem consistent with a model that calls for automatic and parallel extraction of features and their locations, with facilitation-interference effects having their locus in postperceptual response processing.

Attention↗
PubMed1981

Effects of homogeneous and variable exposure on magnitude of adaptation to optical tilt.

Repeated exposure to hallway exploration, alternated with periods of either watching the active hand or exploring a different set of hallways, maintains increasing visual adaptation beyond the point in time at which previous studies using homogeneous exposure have found such visual shift (VS) to be asymptotic. Experiment 1 established that this alternation-repetition effect does not depend on an actual change in task (hall to hand) but also occurs when the task context alone is changed (hall to hall). Experiment 2 compared variable (hall-to-hall) exposure with homogeneous (hall) exposure, showing that variable exposure removes the usual limit on adaptation. In both experiments, proprioceptive shift (PS) and total negative aftereffect (NA) both tended to be less than VS, producing substantial overadditivity (i.e., VS + PS greater than NA). General requirements for an attentional explanation of the alternation-repetition effect are outlined, and possible explanations of overadditivity consistent with the linear model are discussed.

Discrimination Learning↗
PubMed1978

Additivity in adaptation to optical tilt.

Tests of proprioceptive adaptation (head-hand), visual adaptation (eye-head), and both components (eye-hand) were made during 15-min exposure to 20 degrees tilt in two experiments. In both experiments, subjects alternated exposures in which they explored hallways (hall) or viewed their active hand (hand), but in Experiment 2 subjects received two exposures to each condition, while in Experiment 1 only one exposure was given. Hall exposure produced greater visual change, and hand exposure produced greater proprioceptive change; but in both conditions, when order of conditions was controlled, the sum of performance on visual and proprioceptive tests was not statistically different from performance on the common test. In Experiment 2, adaptive components appeared to be inversely related, both within and between exposure conditions, thus providing some evidence of a reciprocal relationship, but a reliable negative correlation between components was not found. Finally, adaptation increased over alternation-repetition of exposure tasks in the second experiment, even though adaptation appeared limited within any given exposure. Results are interpreted in terms of the linear model, and the possible role of attentional factors in processing sensory inconsistencies is discussed.

Adaptation, Ocular↗
PubMed1977

Stroop effect: interference and facilitation with verbal and manual responses.

Two groups of 12 volunteers manually (button pushing) or verbally identified the ink color of 5, randomly ordered and tachistoscopically presented, kinds of stimulus conditons, specified by the nature of the noncolor information and the relationship between color and noncolor information: Congruent Color Words, Noncolor Words, Scrambled Color Words, Nonword Geometric Shapes, and Noncongruent Color Words. With verbal response, facilitation of reaction time occurred for Congruent Color Words compared to Scrambled Color Words and Noncolor Words but not when compared to the Nonword Control, while with manual response facilitation appeared for all comparisons. Interference appeared for both groups, with Noncongruent Color Words having the slowest reaction time. The present design corrected for inadequacies in previous studies and more firmly established the conclusion of parallel perceptual processing of color and noncolor information, with facilitation/interference effects being localized in postperceptual decision operations of signal summation and response competition.

Color Perception↗