PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Distance Perception”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 199 records · Page 11Linked to original sources
PubMed1977

Inappropriate constancy scaling as a factor in the Müller-Lyer illusion.

The inappropriate constancy theory of geometrical illusions assumes the existence of implicit depth cues which automatically set constancy scaling. In the present study the phenomenon of cue conflict has been employed to test for latent depth cues in the Müller-Lyer figures. The technique consisted in introducing a stereoscopic disparity between the figures by means of an aniseikonic lens and measuring the perceived depth between the figures. The magnitude of the stereoscopic effect depends on whether the perspective cues augment or inhibit the stereoscopic depth cues. The results were inconsistent with the misapplied constancy theory, but confirmed Pike & Stacey's (1969) observation that the illusion of size may act as a depth cue.

Adult↗
PubMed1999

Auditory localization of nearby sources. Head-related transfer functions.

Although researchers have long recognized the unique properties of the head-related transfer function (HRTF) for nearby sources (within 1 m of the listener's head), virtually all of the HRTF measurements described in the literature have focused on source locations 1 m or farther from the listener. In this study, HRTFs for sources at distances from 0.12 to 1 m were calculated using a rigid-sphere model of the head and measured using a Knowles Electronic Manikin for Acoustic Research (KEMAR) and an acoustic point source. Both the calculations and the measurements indicate that the interaural level difference (ILD) increases substantially for lateral sources as distance decreases below 1 m, even at low frequencies where the ILD is small for distant sources. In contrast, the interaural time delay (ITD) is roughly independent of distance even when the source is close. The KEMAR measurements indicate that the direction of the source relative to the outer ear plays an important role in determining the high-frequency response of the HRTF in the horizontal plane. However, the elevation-dependent characteristics of the HRTFs are not strongly dependent on distance, and the contribution of the pinna to the HRTF is independent of distance beyond a few centimeters from the ear. Overall, the results suggest that binaural cues play an important role in auditory distance perception for nearby sources.

Dichotic Listening Tests↗
PubMed1970

Underwater vision.

Explore the source record for details and available documents.

Adaptation, Ocular↗
PubMed1971

Perception.

Explore the source record for details and available documents.

Afterimage↗
PubMed1973

Perception.

Explore the source record for details and available documents.

Adaptation, Ocular↗
PubMed1975

Perception.

Explore the source record for details and available documents.

Adaptation, Ocular↗
PubMed2004

Binocular cues and the control of prehension.

The present study was designed to assess the importance of binocular information (i.e. binocular disparity and angle of convergence) in the control of prehension. Previous studies which have addressed this question have typically used the same experimental manipulation: comparing prehensile movements executed either under binocular conditions to those executed when one eye was occluded (monocular). However this may not be the correct comparison as in addition to depriving the subject of binocular depth cues. it also deprives the subject of any visual information in one eye. Therefore we determined the prehensile performance when the subject viewed the target object and scene with either (i) two different views (binocular), (ii) two identical views (bi-ocular), or (iii) one view only (monocular). Overall, the qualitative and quantitative performance in the bi-ocular and monocular control conditions was very similar on all the main measures (and different from the performance in the binocular condition). We conclude that the deficits in performance observed found for 'monocular' reaches should be attributed to the lack of local depth information specified by the binocular cues. In addition we speculate that convergence angle and binocular disparity, although involved in both the pre-movement and movement-execution phases of the reach, the cues may be weighted differently in both phases of a prehension movement depending on the behavioural strategy involved.

Adult↗
PubMed1994

Shifting visual attention in stereographic displays: a time course analysis.

According to a growing number of studies, the stereographic presentation of three-dimensional information improves overall performance relative to displays with only monocular depth cues. Based on studies using real-world, three-dimensional stimuli, however, the efficiency (i.e., speed) of shifting attention between objects located at different depths is impaired relative to that of attention shifts between objects located at the same depth. In the present study we tested whether similar impairments occur when attention is shifted in stereographic space. We compared the time course of attention shifts across and within depth planes using a spatial cuing task. Contrary to the results from studies of real-world stimuli, we found no difference between the time course of within-plane and across-plane attention shifts.

Adult↗
PubMed2001

Runway width effects in the visual approach to landing.

The effect of changes in runway width on the perception of glide-slope has been the subject of extensive investigations. Despite considerable research, an explanation of this effect has been elusive. A mathematical model for glide-slope perception was published recently based on the premise that a desirable goal of perception is to form a perception with minimal uncertainty. One of the qualitative predictions of that model was that changes in the aspect ratio of the runway would affect the perceived glide-slope. In this article, the predictions of the model are quantified and are shown to be in close agreement with experimental results in the literature.

Aerospace Medicine↗
PubMed1985

Changing target size is a stimulus for accommodation.

Accommodation was monitored by using a high-speed infrared optometer while subjects viewed a target that appeared to approach and recede in a sinusoidal manner. The target was presented under open-loop conditions to prevent blurring because of accommodation. The experiments suggest that changing target size can be an effective stimulus on its own. This supports the view that accommodation responds to both dioptric and nondioptric stimuli.

Accommodation, Ocular↗
PubMed1998

Localization of virtual objects in the near visual field.

We examined errors in the localization of nearby virtual objects presented via see-through helmet-mounted displays as a function of viewing conditions and scene content in four experiments using a total of 38 participants. Monocular, biocular, and stereoscopic presentation of the virtual objects, accommodation (required focus), participants' age, and the position of physical surfaces were examined. Nearby physical surfaces were found to introduce localization errors that differ depending on the other experimental factors. These errors apparently arise from the occlusion of the physical background by the optically superimposed virtual objects, but they are modified by participants' accommodative competence and specific viewing conditions. The apparent physical size and transparency of the virtual objects and physical surfaces, respectively, are influenced by their relative position when superimposed. The design implications of the findings are discussed in a concluding section. Head-mounted displays of virtual objects are currently being evaluated as aids for mechanical assembly and equipment maintenance. Other applications include telesurgery, surgical planning, telerobotics, and visualization aids for robotic programming.

Accommodation, Ocular↗
PubMed1968

The bisection of a spatial interval by the pigeon.

Pigeons pecked two response keys to move a white dot until it was equidistant from two other dots on a screen. Continuous records of dot position showed the effects of reinforcement and stimulus parameters upon the accuracy with which the dot was positioned. The method may prove useful for studying the perception of distance in non-human organisms.

Animals↗