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Results for “SIZE PERCEPTION”

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PubMed1979

[The role of the pupil's size in the perception of other persons].

Studies by Hess (1975) show that the pupil serves as a source of information in perception of the emotional state of another person. Large pupils are interpreted in a positive sense. Basing on the results of Hess, the hypothesis that pupil size does not become a relevant variable in person perception until after puberty, was formed. The following result would be interpreted as supporting the hypothesis: since girls reach puberty before boys, more girls should react to pupil size than boys of the same age. 121 students between the ages of 11 and 16 years judged in several statements which of two face photos of a teacher expressed a greater degree of positive attention and esteem towards the students. The two face photos were identical with the exception of pupil size. All age groups rated the photos with larger pupils more positively. Sex differences occurred in the ratings of the 11 to 12-year-olds. Some basic differences between this experiment and that of Hess are discussed.

Adolescent↗
PubMed1992

The effects of colour adaptation and stimulus size on white perception as a function of eccentricity in man.

We studied how much desaturating complementary colour had to be added to blue, green or red after homochromatic adaptation of short duration in order to perceive white or grey at eccentricities of 0-15 deg in the nasal visual field. The CIE 1931 (x,y) chromaticity coordinates corresponding to achromatic perception were subtracted from the chromaticity coordinates of blue, green and red in order to obtain the threshold differences (dx, dy) in chromaticity coordinates. When the stimulus size was constant at all visual field locations, the absolute values of dx and dy decreased with increasing eccentricity, which means that the desaturation threshold for white or grey perception was higher at the fovea than in the periphery. However, when the stimulus size was M-scaled magnifying its size with increasing eccentricity in inverse proportion to the lowest local sampling density of the human retina (cones and ganglion cells at eccentricities 0-10 and above 10 deg, respectively), dx and dy with blue became independent of visual field location except for the very centre of the fovea. However, M-scaling was unsuccessful with green and red. Although M-scaling with green reduced the change in dx and dy as a function of eccentricity, it had no effect on dx and dy with red colour.

Adaptation, Ocular↗
PubMed1997

The effects of class size and form of assessment on nursing students' performance, approaches to study and course perceptions.

Class sizes in nursing education have increased enormously as a consequence of a number of structural changes. This paper reports a study of a large modular nursing degree programme involving the performance of 11799 students on 177 modules over 5 years and the use of the Module Experience Questionnaire on small and large enrollment modules. The study found that nursing students performed less well in large enrollment modules and that they performed better when there was more coursework assessment. Students adopted a surface approach (attempting to memorize material) to a greater extent and a deep approach (attempting to understand material) to a lesser extent on large enrollment modules where pure sciences were being taught. The implications for course design and teaching and assessment methods are discussed.

Clinical Competence↗
PubMed1996

Relative size disparities and the perception of surface slant.

Perceived slant produced by size disparities in random-dot displays was measured by tactile matching. For a 60 deg surface, slant produced by vertical-size disparity (the induced effect) was opposite to that produced by horizontal-size disparity. Overall-size disparity produced a little slant. With small displays, effects of horizontal and vertical disparities were reduced but not those of overall disparity. A zero-disparity surround increased effects of horizontal and overall disparities but reduced the induced effect. A mixture of horizontally disparate and zero-disparity dots produced two slanted surfaces. Vertically disparate and zero-disparity dots produced one slanted surface. Abutting opposite horizontal disparities produced surfaces with a sharp boundary. Abutting vertical disparities produced surfaces with a gradual boundary. Perceived slant depends on the difference between horizontal-size disparity detected locally and mean vertical-size disparity over a relatively large area.

Depth Perception↗
PubMed2002

Heaviness perception. II. Contributions of object weight, haptic size, and density to the accurate perception of heaviness or lightness.

The present study investigated the contributions of object weight, haptic size, and density to the accurate perception of heaviness or lightness in the process of discriminating differences in weight between pairs of cubes with cue conflicts such as that resulting from the size-weight illusion. Fifteen subjects, with visual input blocked and relying on the input gained by grasping the cubes with only their fingertips, attempted to accurately discriminate possible differences in weight factor between the two respective cubes in each step of the trials. Three sets - one set each of copper (CP), aluminum (AL), and plastic (PL) - of seven cubes of various weight (0.10-0.74 N) were used. All of the cubes were covered with smooth, thin vinyl to eliminate possible input concerning density or material per se. Screens were strategically placed to eliminate any visual cues. One hundred and ninety-six trials with 37 combinations were pseudorandomly presented to subjects in the following conditions: PL versus AL, AL versus CP, and CP versus PL. Trials included 2 x 3 combinations on the basis of density (98 trials for higher and 98 for lower conditions) and weight (84 ascending trials for heavier, 28 for identical, and 84 descending for lighter conditions). The response for each trial given by each subject was regarded as correct when it accurately identified the weight relationship between the first and second cube. It was found that the subjects fairly accurately identified the weight relationship when density and weight both increased for the second cube (95.6% for given trials), and when density and weight both decreased (94.6%). The current results were markedly greater than those in the constant-density conditions obtained previously, suggesting that changes in density may be as much of an aid in the perception of heaviness and lightness as is weight. Whenever two cues conflicted directionally with each other, however, accuracy fell dramatically to 33.6% for lower density/ascending weight, and to 22.7% for higher density/descending weight. These results indicate the possibility of two different cues contributing to the perception of heaviness and lightness. Cue conflict such as the size-weight illusion naturally occurs when discriminating weight between objects. The present results, however, suggest that a person may perceive heaviness on the basis of the well-regulated relations between changes of density, size, and weight. The way in which these two cues are related through the haptic size is discussed.

Adolescent↗
PubMed2000

Velocity constancy in a virtual reality environment.

During everyday life the brain is continuously integrating multiple perceptual cues in order to allow us to make decisions and to guide our actions. In this study we have used a simulated (virtual reality--VR) visual environment to investigate how cues to speed judgments are integrated. There are two sources that could be used to provide signals for velocity constancy: temporal-frequency or distance cues. However, evidence from most psychophysical studies favours temporal-frequency cues. Here we report that two depth cues that provide a relative object--object distance--disparity and motion parallax--can provide a significant input to velocity-constancy judgments, particularly when combined. This result indicates that the second mechanism can also play a significant role in generating velocity constancy. Furthermore, we show that cognitive factors, such as familiar size, can influence the perception of object speed. The results suggest that both low-level cues to spatiotemporal structure and depth, and high-level cues, such as object familiarity, are integrated by the brain during velocity estimation in real-world viewing.

Cues↗