Perception of depth in rotating objects: 4. Fluctuating stereokinetic perceptual variants.
Explore the source record for details and available documents.
Depth Perception↗
SEARCH · Search PubMed
Results for “Depth 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.
Perception of depth in rotating objects. 5. Phenomenal motion in stereokinesis.
Explore the source record for details and available documents.
Depth Perception↗
Perception of depth: processing of simple positional disparity as a function of viewing distance.
Explore the source record for details and available documents.
Depth Perception↗
Asymmetries and errors in perception of depth from disparity suggest a multicomponent model of disparity processing.
In three experiments, asymmetries between the processing of crossed and uncrossed disparities were investigated. The target was a luminance-defined circle concentric to a fixation mark, viewed stereoscopically on a computer monitor for 105 msec. Fifteen disparities were presented according to the method of constant stimuli. Observers indicated the apparent direction of target depth relative to fixation. All experiments measured both the accuracy and latency of this response. Experiment 1 showed fewer errors and shorter reaction times for identifying crossed disparities. Experiments 2 and 3 replicated Experiment 1 and also showed that observers may often perceive a target in the direction opposite that prescribed by the disparity information. We propose that the asymmetries and reversals result from differences in computation of sign, not of magnitude. This notion is consistent with a scheme of continuous disparity tuning and accounts for such asymmetries and errors without positing disparity pooling mechanisms.
Adult↗
The effects of binocular and motion-generated information on the perception of depth and height.
Explore the source record for details and available documents.
Depth Perception↗
Binocular eye movements and the perception of depth.
Explore the source record for details and available documents.
Animals↗
The effect of disparity change on binocular visual evoked potential parameters elicited by convergent dynamic random-dot stereogram stimuli in humans.
Binocular visual evoked potentials (VEP) were recorded from the left and right occipital cortices of right-handed subjects in response to six different levels of convergent disparity using the stimulus of dynamic random-dot stereogram (DRDS). The VEP obtained consisted of a negative (N1) and a positive peak (P1) within intervals of 200-400 ms and 400-600 ms, respectively. The latency of the N1 wave decreased with disparity and the amplitude of the same wave displayed a concave-down curve. The tuning-curve of N1 showed that the cortical focus, which produced this wave, was sensitive to mid-disparities. The fact that the tuning-curve of the right hemisphere was sharper than that of the left implied that the right hemisphere was more disparity-selective. In contrast to N1, the change of the latency and the amplitude of the P1 with disparity consisted of concave-up curves. The inverse correlation between the amplitudes of N1 and P1 with disparity made me think that the activation of the neuron population, which gave rise to N1 wave, changed the synchronization level of the cortical focus responsible for the P1 wave. If we keep in mind that the perception of depth is the result of the disparity detection, then we may conclude that N1 is related to disparity detection and P1 is the electrophysiological correlate of a depth percept.
Adult↗
Individual differences in the use of depth cues: implications for computer- and video-based tasks.
This paper reports an experimental study of individual differences in the performance of computer-stimulated and 'real world' versions of an interactive depth perception task. The availability of depth cues (disparity, accommodation, luminance, and texture) was manipulated. Results indicate that ability to perceive depth using binocular cues is not associated with ability to perceive depth using monocular cues. Further, ability to integrate cues was a strong correlate of depth perception when multiple cues were available, and appeared more important in this respect than ability to use individual depth cues. Correlations between psychometric measures of fluid intelligence/spatial ability and depth perception were generally weak, but consistent with the broader pattern of results, suggesting that individual differences in depth perception should currently be regarded as 'cue specific'. Hypothesized facilitative effects of paradoxical monocular stereopsis were not found.
Adult↗
Perceived direction during monocular viewing is based on signals of the viewing eye only.
Perceived visual directions are derived from combining retinal signals and oculomotor signals. Up to now the general belief is that the oculomotor signals of the two eyes are first pooled before they become available for perception of depth and direction. In this sense the eyes are believed to act together as one unit known as the cyclopean eye. This study, however, shows that during monocular viewing in daylight conditions, the perceived directions of objects are indicated by their retinal locus in combination with the angular position of the viewing eye only, the angular position of the closed eye being irrelevant. This result indicates that in binocular vision the integration of left and right eye signals first occurs after retinal and oculomotor signals have been integrated of each eye separately. This conclusion challenges the prevailing concept of cyclopean vision and current views about stereoscopic depth perception.
Adult↗
Assessing a VR-based learning environment for anatomy education.
The purpose of the research proposed herein is to develop an empirical, methodological tool for the assessment of visual depth perception in virtual environments (VEs). Our goal is to develop and employ a behaviorally-based method for assessing the impact of VE design features on the perception of visual depth as indexed by the performance of fundamental perceptual-motor activities. Specifically, in this experiment we will assess the affect of two dimensions of VE system design--(1) viewing condition or "level of immersion", and (2) layout/design of the VE--on the performance of an engaging, game-like task. The characteristics of the task to be employed are as follows--(1) it places no demands on cognition in the form of problem solving, retrieval of previously learned information, or other analytic activity in order to assure that (2) variations in task performance can be exclusively attributed to the extent to which the experimental factors influence visual depth perception. Subjects' performance will be assessed in terms of the speed and accuracy of task performance, as well as underlying dimensions of performance such as workload, fatigue, and physiological well being (i.e., cybersickness). The results of this experiment will provide important information on the effect of VE immersion and other VE design issues on human perception and performance. Further development, refinement, and validation of this behaviorally-based methodology will be pursued to provide user-centered design criteria for the design and use of VE systems.
Anatomy↗
The moon illusion: a test of the vestibular hypothesis under monocular viewing conditions.
The results of earlier monocular experiments on the moon illusion have been either negative or confounded. To test the role of vestibular function, 24 subjects made forced-choice distance comparisons between stimuli mounted in translucent tubes. The stimulus tube for standard distance could be positioned in three viewing angles (45 degrees up, horizontal, and 45 degrees down). A comparison tube adjustable for distance was mounted horizontally. There was a greater perception of depth in the downward looking condition. The relatively weak effects are discussed in terms of a two-hypothesis explanation of the real-life moon illusion and the poor cues for depth perception in monocular viewing.
Astronomical Phenomena↗
Eye movements provide the extra-retinal signal required for the perception of depth from motion parallax.
It has been unclear whether the perception of depth from motion parallax is an entirely visual process or whether it requires extra-retinal information such as head movements, vestibular activation, or eye movements. Using a motion aftereffect and static test stimulus technique to eliminate visual cues to depth, this psychophysical study demonstrates that the visual system employs a slow eye movement signal, optokinetic response (OKR) in particular, for the unambiguous perception of depth from motion parallax. A vestibular signal, or vestibularly driven eye movement signal is insufficient for unambiguous depth from motion parallax. Removal of the OKR eye movement signal gives rise to ambiguous perceived depth in motion parallax conditions. Neurophysiological studies suggest a possible neural mechanism in medial temporal and medial superior temporal cortical neurons that are selective to depth, motion, and direction of eye movement.
Depth Perception↗
Binocular disparity can explain the orientation of ocular dominance stripes in primate primary visual area (V1).
In the primate primary visual area (V1), the ocular dominance pattern consists of alternating monocular stripes. Stripe orientation follows systematic trends preserved across several species. I propose that these trends result from minimizing the length of intra-cortical wiring needed to recombine information from the two eyes in order to achieve the perception of depth. I argue that the stripe orientation at any point of V1 should follow the direction of binocular disparity in the corresponding point of the visual field. The optimal pattern of stripes determined from this argument agrees with the ocular dominance pattern of macaque and Cebus monkeys. This theory predicts that for any point in the visual field the limits of depth perception are greatest in the direction along the ocular dominance stripes at that point.
Animals↗
The perception of depth and slant from texture in three-dimensional scenes.
The perception of depth and slant in three-dimensional scenes specified by texture was investigated in five experiments. Subjects were presented with computer-generated scenes of a ground and ceiling plane receding in depth. Compression, convergence, and grid textures were examined. The effect of the presence or absence of a gap in the center of the display was also assessed. Under some conditions perceived slant and depth from compression were greater than those found with convergence. The relative effectiveness of compression in specifying surface slant was greater for surfaces closer to ground planes (80 degrees slant) than for surfaces closer to frontal parallel planes (40 degrees slant). The usefulness of compression was also observed with single-plane displays and with displays with surfaces oriented to reduce information regarding the horizon.
Computer Graphics↗
Vergence eye movements facilitated by saccades.
This study was carried out to determine whether the vergence velocity is influenced or not by the richness in visual cues for the perception of depth and by the association of saccade. Vergence eye movements associated with and without saccades were recorded in 4 normal subjects with two CCD cameras in both dark and illuminated rooms. Subjects fixated between the targets, which differed in direction and in depth. The peak vergence velocity was 50 degrees to 90 degrees per second for 10 degrees vergence change and 30 degrees to 70 degrees per second for 5 degrees vergence change. Transient vergence change was found during horizontal or vertical saccade. Even after deleting this transient vergence change, the peak velocity of vergence became faster when it was associated with vertical or horizontal saccade. Trajectories of fixation locus were calculated when the vergence and saccade were required simultaneously. Whether or not the room was rich in visual cues for depth perception seemed to have no effect on vergence velocity. Blinking also speeded up divergence. Most eye movements in daily life are the combination of vergence and saccade, and this vergence facilitation by saccade helps to attain prompt binocular fixation on the new target.
Adult↗
Visual characteristics of clay target shooters.
A comprehensive battery of standardised visual tests was administered to 11 skilled and 12 novice clay target shooters in an attempt to determine the distinctive visual characteristics of expert performers in this sport. The static and dynamic visual acuity, ocular muscle balance, ocular dominance, depth perception and colour vision of each of the subjects was measured in addition to their performance on simple and choice reaction time, peripheral response time, rapid tachistoscopic detection, coincidence timing and eye movement skills tasks. Expert superiority was observed on the simple reaction time measure only, and the novices actually outperformed the skilled subjects on a number of the other visual measures (viz., static acuity at near distance, dynamic acuity, vertical ocular muscle balance, choice reaction time and rapid target detection discriminability). Scores on all measures for both groups were within the expected normal range indicating that normal and not necessarily above-average basic visual functioning is sufficient to support skilled clay target shooting. An important implication of the finding that skilled shooters are not characterised by supranormal levels of basic visual functioning is the recognition that any attempt to improve shooting performance through training of general attributes of vision to supranormal levels is likely to be unproductive.
Adolescent↗
Learning arthroscopy.
Problems have been uncovered in learning arthroscopy at the resident level or for the beginner at any level of orthopedic practice. The problems are varied, and are not all present in the same individual. This study delineates problems involving vision impairments, depth perception, spatial recognition, speed of accommodation, and data confrontation requiring immediate action. Speed is an additional factor in relation to accomplishing a task within an acceptable time limit. Through testing mechanisms, surgeons can discover their own inadequacies and thus learn to perform well in this new field.
Arthroscopy↗
Binocular chromatic rivalry and single vision.
Depth perception is known to be impaired for chromatic equiluminant patterns. To investigate this phenomenon I have compared the effects of binocularly presented stimuli in the form of stripes, which contain only luminance information with similarly presented stimuli which contain only chromatic information. Observations of the reported percepts for the two conditions demonstrate that mechanisms of colour vision can impede stereopsis based on binocular fusion when the chromatic stripes are at, or even near, equiluminance, provided that their saturation is high. This observation is consistent with inhibitory interactions within the chromatic-sensitive neuronal groupings in the visual cortex.
Color Perception↗