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At least 685 records · Page 38Linked to original sources
PubMed1991

The height + width = area of a rectangle rule in five-year-olds: effects of stimulus distribution and graduation of the response scale.

This study attempts to account for disparities between the Anderson and Cuneo (1978), Leon (1982), and Lautrey, Mullet, and Paques (1989) studies in regard to children's area judgment. Two task variables were manipulated: stimulus distribution (biased/unbiased) and the type of response scale (graduated/ungraduated). Three age groups (5, 6, and 7 year olds) were tested. The mean integration pattern for 5-year-olds presented a negatively biased stimulus distribution, and an ungraduated response scale was highly convergent and suggested the use of a centration rule (replication of the Lautrey et al. results). When 5-year-olds were presented with an unbiased stimulus distribution and a graduated scale, the integration pattern was only slightly convergent (as in Leon). The effects of two factors (age and graduation) were significant and combined additively: The older the child, the more graduated the response scale and the more the integration pattern tended to form three ascending parallel lines (the Anderson & Cuneo results).

Child Development↗
PubMed1983

The brain as a geometer.

The fragmentary cues we have on the geometric aptitudes of the brain (e.g., in evaluating shapes or appreciating depth) do not lead to a unified model of perceptual geometry. In parallel with physiological studies, aimed at explaining how perception works, I suggest developing the study of the geometrical capabilities of the brain, in order to learn precisely what is accomplished.

Brain↗
PubMed1993

Spatial localization of motion-defined and luminance-defined contours.

Thresholds for the vernier alignment of contours defined by luminance and coherent random-dot motion were measured. The luminance-defined contours were localized with a precision better than the receptor grain, while the motion-defined contours were localized more poorly than this limit. When motion-defined and luminance-defined targets were matched for dot density, vernier thresholds were equivalent at low densities. When the targets were also equated for perceived contrast, the vernier thresholds became equivalent at higher densities as well. These results suggest that the precision with which motion-defined contours are localized is contrast and sample limited. Next, the localization mechanism for motion-defined targets was investigated. Length summation limits were similar for motion-defined and luminance-defined targets, suggesting that these targets could be localized by a common mechanism. Vernier targets were then flanked by two additional bars. Motion-defined flanks interfered with the localization of motion-defined targets and luminance-defined flanks interfered with the localization of luminance-defined targets. However, motion-defined and luminance-defined bars did not interact to produce spatial interference. This result indicates that the mechanisms for localizing luminance-defined and motion-defined targets are independent. We suggest that parallel mechanisms govern the vernier localization of motion-defined and luminance-defined targets.

Contrast Sensitivity↗
PubMed2007

Is there a general task switching ability?

Participants were tested on two analogous task switching paradigms involving Shape/Size tasks and Vertical/Horizontal tasks, respectively, and three measures of psychometric intelligence, tapping fluid, crystallized and perceptual speed abilities. The paradigms produced similar patterns of group mean reaction times (RTs) and the vast majority of the participants showed switching cost (switch RT minus repeat RT), mixing cost (repeat RT minus single-task RT) and congruency effects. The shared intra-individual variance across paradigms and with psychometric intelligence served as criteria for general ability. Structural equations modeling indicated that switching cost with ample preparation ("residual cost") and mixing cost met these criteria. However, switching cost with little preparation and congruency effects were predominantly paradigm specific.

Female↗
PubMed2004

Asymmetry in the perception of motion-in-depth.

We investigated the anisotropic responses between the detection of motion toward and motion away from the observers with expanding/contracting shaded circles. Our experiments followed visual search paradigm with two exceptions: (1) the stimulus presentation time was fixed for 300 ms and (2) the mean error rates were adopted as a dependent variable. In Experiment 1, targets and distractors were defined by expanding (or contracting) convex/concave circles. Results of Experiment 1 suggested that the human visual system is more sensitive to expanding convex circles (which create the impression of approaching objects) than others. In Experiment 2, the targets and distractors were defined by expanding (or contracting) step gradient (top-lighting/bottom-lighting) circles. The results of Experiment 2 suggest that the anisotropy for the perception of motion-in-depth should not be caused by change of luminance polarity but by change of shading cue.

Adolescent↗
PubMed1985

Positional differences in performance on members of confusable and nonconfusable letter pairs.

A parafoveally presented letter is more accurately identified when flanked by a letter to its foveal side than when flanked by one to its peripheral side, but only if the two letters are nonconfusable. With confusable letters there is no such relative position effect. Four experiments indicated that the basis for this confusability-asymmetry interaction is not criterion or response bias, but rather that it occurs earlier in visual processing. In Experiment 1 the interaction was found when only one pair member was reported, thus eliminating response bias requiring the report of both letters as the source of the effect. In Experiment 2 the data were subjected to signal detection analysis, and the interaction persisted. In Experiment 3 pair members were presented simultaneously or in rapid sequence, and the interaction was found only with simultaneous presentations. In Experiment 4 letters were used with upper- and lowercase counterparts that were quite different in shape. Uppercase letters that were most and least confusable for each subject were paired for presentation in their upper case form or in mixed-case form. The interaction occurred only with upper-case pairs.

Attention↗
PubMed1995

Comparing depth from motion with depth from binocular disparity.

The accuracy of depth judgments that are based on binocular disparity or structure from motion (motion parallax and object rotation) was studied in 3 experiments. In Experiment 1, depth judgments were recorded for computer simulations of cones specified by binocular disparity, motion parallax, or stereokinesis. In Experiment 2, judgments were recorded for real cones in a structured environment, with depth information from binocular disparity, motion parallax, or object rotation about the y-axis. In both of these experiments, judgments from binocular disparity information were quite accurate, but judgments on the basis of geometrically equivalent or more robust motion information reflected poor recovery of quantitative depth information. A 3rd experiment demonstrated stereoscopic depth constancy for distances of 1 to 3 m using real objects in a well-illuminated, structured viewing environment in which monocular depth cues (e.g., shading) were minimized.

Adult↗
PubMed1980

Laterality effects, levels of processing, and stimulus properties.

Two hypotheses of hemispheric specialization are discussed. The first stresses the importance of the kind of processing to which the stimulus is subjected, and the second stresses the importance of the nature of the stimulus. To test these hypotheses, four experiments were carried out. In Experiment 1 verbal material was employed in a same-different classification task, and an overall right visual field superiority was found. Experiment 2, in which verbal stimuli were subjected to visuospatial transformations (i.e. mental rotations), yielded no laterality effect. In Experiment 3 geometrical figures were employed in a classification task similar to that of Experiment 1, and an overall left visual field superiority was found. In Experiment 4 both verbal and geometric stimuli were employed. The results showed a significant interaction between field of presentation and nature of the stimulus and no interaction between field of presentation and level of processing.

Discrimination Learning↗
PubMed1981

Congruity and the perceptual comparison task.

The effects of congruity between comparatives and the relative magnitudes of to-be-compared stimuli were investigated in six perceptual comparison experiments. Experiments 1-5 failed to obtain congruity effects in purely perceptual tasks even when subjects had extensive practice with a relatively small stimulus set. Experiment 6 obtained a congruity effect with perceptual stimuli but only when the stimuli were described as representing real-world objects. All of the results indicated that congruity effects occur only in tasks that include major symbolic or memorial components; a review of the perceptual comparison literature reveals consistent support for this position. These findings are discussed in terms of expectancy and semantic coding interpretations of the congruity effect.

Discrimination Learning↗
PubMed1984

Given versus induced category representations: use of prototype and exemplar information in classification.

Acquisition of category-level information can be based on experience with category members (induced) as well as on direct presentation of prototypical values (given). To investigate the effects of these two types of information, a relational coding model of categorization was developed in which classification is based on a mixture of exemplar and prototype information. In two experiments, subjects learned about two ill-defined categories. Stimuli were geometric shapes varying along four binary-valued dimensions. For three groups of subjects, training consisted of (a) experience with exemplars only, (b) learning prototype values followed by exemplar experience, or (c) learning prototype values concurrently with exemplar experience. Following training, all subjects received classification tests on prototype values as well as on old and new exemplars. By varying the relative use of prototype and exemplar information, the mixture model accurately accounted for category judgements in all three groups. For subjects directly presented with prototype values, classification was based on a mixture of similarity to prototypes and to stored exemplars. In contrast, subjects who only received experience with exemplars appeared to base their category judgements solely on similarity to stored exemplars, even though they could accurately judge the prototype values. The two components of the mixture model are related to subjects' classification strategies and the nature of abstracted, category-level information.

Adult↗
PubMed1989

A model of perceptual classification in children and adults.

The developmental trend from overall-similarity to dimensional-identity classifications is explained by a quantitative model. I begin with the assumption that objects are represented in terms of constituent dimensions and that the representation of objects changes little with development. Given this assumption, the model has three major parts. First, the similarity between objects is a function of the combination of the constituent dimensional differences. I propose developmental change in the likelihood that dimensions are differentially weighted in the calculation of similarity. Second, the perceived similarities between objects are valued for the purpose of constructing classifications. I propose that similarities are valued more dichotomously with age, such that identity becomes increasingly special. Third, the valued similarities are used to choose the best classification of those possible. The model provides good qualitative fits to the extant data. Three experiments examining classifications in 2- to 8-year-olds and in adults support specific new claims of the model. The data and the model provide new insights about development, classification, and similarity.

Adult↗
PubMed1997

Stimulus modality and stimulus-response compatibility in absolute identification.

Accuracy and response time (RT) were measured in the absolute identification (AI) of 10 unidimensional perfectly pairwise discriminable stimuli. One group of 20 subjects performed a visual AI task involving line segments of variable length. A second group of 20 subjects participated in an auditory task with the stimuli composed of pure tones of variable intensity. Subjects performed the task under two conditions: a spatially compatible and a spatially incompatible stimulus-response mapping. Results showed greater accuracy for the visual modality and longer RT for the incompatible mapping. The experimental factors did not substantially alter the bowing observed when performance was plotted according to the ordinal position of the stimuli. The data do not support the hypothesis that the bow effect is attributable to motor programming or motor adjustment stages.

Acoustic Stimulation↗