Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SIZE PERCEPTION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed1981

Perception of runway image shape and approach angle magnitude by pilots in simulated night landing approaches.

One cue for visual judgments of glidepath angle has been referred to as form ratio. Form ratio is defined as the ratio of vertical height of the runway to width of the far end in the runway retinal image. The ability of pilots to judge form ratios was compared with the ability to judge approach angles in the nighttime "black hole" situation in two experiments. Responses in both static and dynamic simulated approach conditions indicated a general tendency to overestimate form ratios and approach angles less than 3 degrees. Intersubject and intrasubject variability of form ratio and approach angle responses were comparable. These findings (i) do not support the utility of form ratio judgments as an aid in selecting approach angle, (ii) add to the empirical evidence of visual illusions and the danger of reliance on visual information for judgment of approach angle in the nighttime "black hole" situation where only runway light are visible, and (iii) point to variability in perception of approach angle as an important part of the problem.

Adult↗
PubMed1998

Eight-and-a-half-month-old infants' reasoning about containment events.

The present research examined whether 8.5-month-old infants take into account the width and compressibility of an object when determining whether it can be inserted into a container. The infants in Experiment 1 saw 2 test events. At the start of each event, a tall container rested on the apparatus floor. Next, the container was hidden by a screen, and a large ball attached to the lower end of a rod was introduced into the apparatus and lowered behind the screen into the container. Finally, the screen was removed to reveal the ball's rod protruding above the container's rim. The only difference between the 2 test events had to do with the width of the containers: in 1 event (large-container event), the container was slightly wider than the ball; in the other event (small-container event), the container was only half as wide as the ball, so that it should have been impossible for the ball to be lowered into it. Infants in a control condition saw identical test events except that a small ball was used that could fit into either the large or the small container. The infants in the experimental condition looked reliably longer at the small- than at the large-container event, whereas those in the control condition tended to look equally at the 2 events. These results suggested that, although the infants never saw the ball and the container simultaneously, they realized that the large ball could fit into the large but not the small container, whereas the small ball could fit into both containers. In Experiment 2, the large ball used in Experiment 1 was replaced with an equally large but compressible ball. The results were negative, suggesting that the infants understood that the large compressible ball could be inserted into either the small or the large container. Finally, Experiment 3 confirmed the results of the experimental condition in Experiment 1, with a slightly different procedure. Together, the present results indicate that, by 8.5 months of age, infants are already capable of sophisticated reasoning about containment events.

Attention↗
PubMed2002

Perception of two-body center of mass.

Participants estimated the perceptual center of mass between two horizontally oriented black dots varying in size and distance. Experiment 1 showed that estimates, measured as distance from the larger dot's center, decreased with an increase in size ratio between the dots and a decrease in the distance between them, as predicted by the physical center-of-mass equation. The results were replicated and extended in further experiments with different ratios and distances. In all experiments, the true center was consistently overestimated, either because the stimuli were perceived in a low dimensionality or because of a hesitancy to place estimates near the larger dot's edge. In Experiment 4, the center was deliberately placed near this edge for one- and two-dimensional solutions. Participants still overestimated, indicating an "edge effect" as responsible.

Adolescent↗
PubMed1979

An exploration of perception of body boundary, personal space, and body size in elderly persons.

A study of 108 elderly persons using the Body Distortion Questionnaire and the personal space simulation technique test did not support hypotheses that elderly persons with a large personal space will have a larger distortion of body boundary, a larger perception of large body size, a smaller perception of small body size, a larger distortion of body size, and a larger body distortion than elderly persons with a small personal space. The analyses with one-tail t tests showed elderly persons with a small personal space have a larger perception of large body size and a larger distortion of body size than elderly persons with a large personal space. When the extremes of personal space were used the results were the same. Males have a larger personal space and greater distortion of skin perceptions than females.

Aged↗
PubMed1983

Depth perception in Pandora's box and size illusion: evolution with age.

The aim of the experiment was to study the evolution with age (6, 8, 11 and 14 years) of pictorial depth perception in Pandora's box and to compare it with the evolution of size illusion with the same subjects and the same pictorial backgrounds. In addition to familiar size and relative position, each pictorial stimulus contained one or more of the following depth cues: linear perspective, texture gradient, and interposition. The two kinds of measurements produced different results. Size illusions, although present, did not vary with age but increased with the number of cues. Estimates of distance in Pandora's box increased with age and varied according to the type of cue present: texture gradient seemed to be critical to the amount of depth perceived. The correlation between size adjustments and distance adjustments was significant only for the two oldest groups of subjects (11 and 14 years).

Adolescent↗
PubMed1993

Anisotropies in the perception of stereoscopic surfaces: the role of orientation disparity.

We measured stereoscopic slant detection thresholds for surfaces slanting about a horizontal or a vertical axis. For random-dot covered surfaces, 1.25 deg of slant was required to detect slant about a horizontal axis, whereas 2.1 deg of slant was required to detect slant about a vertical axis. This anisotropy could be due to the fact that orientation disparities, which contain information about surface slant, are generally smaller for surfaces slanting about a vertical axis. To test this possibility, slant thresholds were measured for surfaces whose orientation disparity content was manipulated independently of the other slant information present. When the magnitude of orientation disparity was the same for surfaces slanting about a horizontal and a vertical axis, both surface orientations required about 1.5 deg of slant to be detected; thus the anisotropy became negligible. In contrast, when the orientation disparity content of a surface slanting about a vertical axis was zero, 3-4 deg of slant was required for detection; thus the anisotropy became larger. Under the conditions of these experiments, it appears that the visual system utilizes orientation disparities.

Depth Perception↗
PubMed1995

Object representation by cores: identifying and representing primitive spatial regions.

We propose a model of the spatial visual processes underlying the identification and representation of the shape of primitive spatial regions. We propose that a region's boundaries are sensed at multiple scales by boundariness detectors that give graded responses, that stimulated boundariness detectors of similar scale, sigma, connect to one another across a distance that is proportional to their scale, and that they connect via cores, where a core encodes the middles and widths of the region and hence is a trace in (chi, gamma, sigma), i.e. 3-D scale space.

Form Perception↗
PubMed1988

Brain potentials during mental distance judgments.

Visual event-related potentials were recorded from a group of 10 normal subjects while they judged the proximity of two letters of the alphabet. Subjects viewed singly the letters A, D, G, L, N, T, W and Z and indicated by button press whether the letter displayed occurred before or after the comparison letter M. Reaction times to close letters (L and N) were longer than ordinally more distant letters (A, D, G, T, W, Z). A late parietally positive potential of approximately 475 ms covaried in latency and amplitude with these judgments. Late potentials were delayed in latency and reduced in amplitude to close letter (L and N) judgments compared to the other letters. The results suggest that mental processes, such as alphabetic distance judgments, may be usefully studied by examining their associated event-related potentials.

Adult↗