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British Journal of Psychology (London,... Feb 2021Depth perception is essential for effective interaction with the environment. Although the accuracy of depth perception has been studied extensively, it is unclear how...
Depth perception is essential for effective interaction with the environment. Although the accuracy of depth perception has been studied extensively, it is unclear how accurate the depth information is stored in working memory. In this study, we investigated the accuracy and systematic biases of depth representation by a delayed estimation task. The memory array consisted of items presented at various stereoscopic depth positions, and the participants were instructed to estimate the depth position of one target item after a retention interval. We examined the effect of spatial configuration by comparing the memory performance in the whole-display condition where non-target memory items were present during retrieval with that in the single-display condition where non-target memory items were absent. In the single-display condition, we found an overestimation bias that the depth estimates were farther than the corresponding depth positions defined by disparity, and a contraction bias that the stored depth positions near the observer were overestimated and those far from the observer were underestimated. The magnitude of these biases increased with the number of to-be-stored items. However, in the whole-display condition, the overestimation bias was corrected and the contraction bias did not increase with the number of to-be-stored items. Our findings suggested that the number of to-be-stored items could affect the accuracy of depth working memory, and its effect depended crucially on whether the information of spatial configuration of memory display was available at the retrieval stage.
Topics: Bias; Depth Perception; Humans; Memory, Short-Term; Visual Perception
PubMed: 32621652
DOI: 10.1111/bjop.12456 -
Vision Research May 2022The ability to visually perceive distances in depth was evaluated in two experiments. In both experiments, the observers were required to bisect a distance interval...
The ability to visually perceive distances in depth was evaluated in two experiments. In both experiments, the observers were required to bisect a distance interval oriented in depth (8 m total extent in Experiment 1 and 7 m in Experiment 2). The purpose of Experiment 1 was to examine the effects of environmental context (indoors in the dark, indoors in the light, and outdoors) and monocular versus binocular viewing. The purpose of Experiment 2 was to manipulate linear perspective to determine its importance for perceiving depth interval magnitudes. In the outdoor environment, the observers' bisection judgments indicated perceptual compression of farther distances similar to that obtained in many previous studies. In contrast, the observers' judgments in the indoor lighted environment were consistent with the perceptual expansion of farther distances. There was also a beneficial effect of binocular viewing upon the precision of the observers' repeated judgments, but the size of this effect was large only within the dark environment. Finally, linear perspective was found to significantly modulate the observers' bisection judgments such that they became accurate only when perspective was available.
Topics: Depth Perception; Distance Perception; Humans; Judgment; Vision, Binocular; Vision, Ocular; Visual Perception
PubMed: 35030510
DOI: 10.1016/j.visres.2021.107992 -
Seminars in Ophthalmology Feb 2020Multiple sclerosis (MS) is an acquired demyelinating and inflammatory neurodegenerative disease affecting the central nervous system (CNS). Clinical and subclinical... (Review)
Review
Multiple sclerosis (MS) is an acquired demyelinating and inflammatory neurodegenerative disease affecting the central nervous system (CNS). Clinical and subclinical ocular disturbances occur in almost all patients with MS. The objective of this narrative review was to collect and summarize the available scientific information on oculomotor, accommodative and binocular alterations that have been reported in MS. A systematic search strategy with the following descriptors was carried out: multiple sclerosis, ocular motility disorders, internuclear ophthalmoplegia, nystagmus, vergences, fixation, pupil reflex, accommodation and stereopsis. According to the search, some oculomotor alterations were found to be commonly reported in MS, such as alterations in saccades and nystagmus. In contrast, accommodative, vergence and stereopsis alterations have not been comprehensively studied despite their relevance, with only minimal evidence showing a potential negative impact of the disease on these aspects. In conclusion, oculomotor impairment is a common component of disability in MS patients and should be considered when managing this type of patients. More research is still needed to know the real impact of this disease on binocular vision and accommodation.
Topics: Accommodation, Ocular; Depth Perception; Humans; Multiple Sclerosis; Ocular Motility Disorders; Saccades; Vision, Binocular
PubMed: 32228341
DOI: 10.1080/08820538.2020.1744671 -
The Journal of Neuroscience : the... Feb 2015As an observer translates, objects lying at different distances from the observer have differential image motion on the retina (motion parallax). It is well established...
As an observer translates, objects lying at different distances from the observer have differential image motion on the retina (motion parallax). It is well established psychophysically that humans perceive depth rather precisely from motion parallax and that extraretinal signals may be used to correctly perceive the sign of depth (near vs far) when binocular and pictorial depth cues are absent or weak. However, the neural basis for this capacity remains poorly understood. We have shown previously that neurons in the macaque middle temporal (MT) area combine retinal image motion with smooth eye movement command signals to signal depth sign from motion parallax. However, those studies were performed in animals that were required simply to track a visual target, thus precluding direct comparisons between neural activity and behavior. Here, we examine the activity of MT neurons in rhesus monkeys that were trained to discriminate depth sign based on motion parallax, in the absence of binocular disparity and pictorial depth cues. We find that the most sensitive MT neurons approach behavioral sensitivity, whereas the average neuron is twofold to threefold less sensitive than the animal. We also find that MT responses are predictive of perceptual decisions (independent of the visual stimulus), consistent with a role for MT in providing sensory signals for this behavior. Our findings suggest that, in addition to its established roles in processing stereoscopic depth, area MT is well suited to contribute to perception of depth based on motion parallax.
Topics: Animals; Depth Perception; Discrimination, Psychological; Macaca mulatta; Male; Motion Perception; Neurons; Photic Stimulation; Psychomotor Performance; Pursuit, Smooth; Temporal Lobe; Vision Disparity; Visual Pathways
PubMed: 25673864
DOI: 10.1523/JNEUROSCI.3134-14.2015 -
Die Ophthalmologie Jul 2022Optimal visual abilities including stereo acuity seem to be an important issue in sports. There is increasing evidence that stereo acuity can be sustainably improved by...
BACKGROUND
Optimal visual abilities including stereo acuity seem to be an important issue in sports. There is increasing evidence that stereo acuity can be sustainably improved by digital vision training even for people with good stereo acuity.
STUDY DESIGN AND TEST METHODS
In this study 31 male and female tennis players (professionals, young professionals, coaches and former professionals) completed at least 6 training units each with 192 dynamic stereoscopic tasks (N = 1152) within 6 weeks including a 4-option test with different levels of difficulty on a 3D screen at a distance of 5 m. The parameter reaction time and correctness at 15-300 arcseconds was determined. For a more precise representation of the reaction time improvement as a function of the difficulty level, the parameter reaction time increase per stereo disparity reduction (ReST) was defined.
RESULTS
Reaction time to 15 arcsecond stimuli significantly decreased from 3.9 s to 1.6 s (59%) as a result of digital vision training. The correctness at 30 arcsecond stimuli significantly increased by 23%.
DISCUSSION
The observed improvement in reaction time during vision training did not result in decreasing correctness when answering the visual questions. This represents an overall improvement in stereo vision.
CONCLUSION
Dynamic visual training over 6 weeks improves stereoscopic performance including stereo acuity, response time and correctness.
Topics: Athletes; Depth Perception; Female; Humans; Male; Tennis; Vision, Binocular; Visual Acuity
PubMed: 35107596
DOI: 10.1007/s00347-022-01574-x -
Perceptual and Motor Skills Oct 2018Typically, infants younger than four months fail to attend to the left side of their spatial field, most likely due to an innate asymmetrical tonic neck reflex (ATNR).... (Review)
Review
Typically, infants younger than four months fail to attend to the left side of their spatial field, most likely due to an innate asymmetrical tonic neck reflex (ATNR). In a critical transition, by four months of age, infants begin to reach and develop depth perception; and, by five months, they tend to monitor the entire spatial field. However, this developmental transition can be delayed. Moreover, there is always a residual right-sided spatial bias under cognitive load, a phenomenon that may also occur among adult stroke patients. While causative factors of biased visual attention in both infants and brain-injured adults may vary, mechanisms of remediation may be similar. This literature review addresses whether the infant's emergence of attention toward a full visual spatial field and the associated shift from monocular to binocular vision occurs because of (a) increased left side reaching, loosening the rarely mentioned high muscle tension ATNR or (b) maturational resolution of visual asymmetry in motion perception. More research is needed to investigate the origins of the infants' visual control system and factors involved in its development, especially because Alzheimer and dementia patients may also show primitive two-dimensional vision and deficits in perceiving objects-in-motion that seem to mirror infant visual perception.
Topics: Attention; Attentional Bias; Child Development; Depth Perception; Humans; Infant; Motion Perception; Neck; Reflex; Vision, Ocular; Visual Fields; Visual Perception
PubMed: 30016907
DOI: 10.1177/0031512518786131 -
Strabismus Sep 2020Nagel's book on vision with two eyes was published in 1861, during a period in which German visual scientists were struggling to rescue the doctrine of identical retinal...
Nagel's book on vision with two eyes was published in 1861, during a period in which German visual scientists were struggling to rescue the doctrine of identical retinal points from the evidence of stereoscopic depth. The long observational history of binocular vision has been dominated by the appearance of a single world with two eyes and its breakdown when the eyes are distorted abnormally. Early in the nineteenth century the flat horopter of Aguilonius (proposed two centuries earlier) assumed curvature in the form of the Vieth-Müller circle which was linked to identical retinal points: there were only two possible states of binocular perception - singleness with images on the Vieth-Müller circle and doubleness otherwise. This elegant edifice was undermined when Wheatstone demonstrated singleness and depth from images with slight retinal disparities. Nagel responded by providing observations on combining simple line stimuli in the two eyes. In the last part of chapter 3 of his book, Nagel describes experiments with lines varying in orientation or curvature with respect to the two eyes; it is in this section that Nagel draws attention to cyclofusion and the involvement of the extraocular muscles in it. Ocular torsion was an issue of considerable contention in nineteenth century visual science. The possibility of torsion in opposite directions seemed fanciful and yet this is what Nagel proposed in order to maintain cyclofusion for lines inclined in opposite directions relative to the horizontal. Similar rotations about the vertical resulted in a depth effect with no cyclovergence. The involvement of cyclovergence remained hotly debated until photographic recording of eye movements verified it.
Topics: Books; Depth Perception; Germany; History, 19th Century; Humans; Ophthalmology; Vision, Binocular
PubMed: 32813596
DOI: 10.1080/09273972.2020.1802181 -
Investigative Ophthalmology & Visual... Jul 2016A clinical diagnosis of stereoblindness does not necessarily preclude compelling depth perception. Qualitative observations suggest that this may be due to the dynamic... (Comparative Study)
Comparative Study
PURPOSE
A clinical diagnosis of stereoblindness does not necessarily preclude compelling depth perception. Qualitative observations suggest that this may be due to the dynamic nature of the stimuli. The purpose of this study was to systematically investigate the effectiveness of static and dynamic stereoscopic stimuli.
METHODS
Stereoscopic stimuli were presented on a passive polarized stereoscopic monitor and were manipulated as follows: static disparity (baseline condition), dynamic disparity (change in z-location), change in stimulus pattern, change in z-location with pattern change, change in x-location (horizontal shift), a control (nil-disparity signal). All depth-detection thresholds were measured simultaneously using an adaptive four-alternative-forced-choice (4AFC) paradigm with all six conditions randomly interleaved.
RESULTS
A total of 127 participants (85 women, 42 men; mean [SD] age, 21 [5] years) with visual acuity better than 0.22 logMAR in both eyes were assessed. In comparison to the static disparity condition, depth-detection thresholds were up to 50% lower for the dynamic disparity conditions, with and without pattern change (P < 0.001). The presence of a changing pattern in isolation (P = 0.71) or a horizontal shift (P = 0.41) did not affect the thresholds.
CONCLUSIONS
Dynamic disparity information facilitates the extraction of depth in comparison to static disparity signals. This finding may account for the compelling perception of depth reported in individuals with no measurable static stereoacuity. Our findings challenge the traditional definition of stereoblindness and suggest that current diagnostic tests using static stimuli may be suboptimal. We argue that both static and dynamic stimuli should be employed to fully assess the binocular potential of patients when considering management options.
Topics: Cues; Depth Perception; Female; Humans; Male; Motion Perception; Pattern Recognition, Visual; Photic Stimulation; Sensory Thresholds; Vision Disparity; Vision, Binocular; Young Adult
PubMed: 27379579
DOI: 10.1167/iovs.15-18104 -
Journal of Vision Oct 2023When an observer moves in space, the retinal projection of a stationary object either expands if the motion is toward the object or shifts horizontally if the motion...
When an observer moves in space, the retinal projection of a stationary object either expands if the motion is toward the object or shifts horizontally if the motion contains a lateral component. This study examined the impact of expansive optic flow and lateral motion parallax on the accuracy of depth perception for observers with normal or artificially reduced acuity and asked whether any benefit is due to the continuous motion or to the discrete object image displacement. Stationary participants viewed a virtual room on a computer screen. They used an on-screen slider to estimate the depth of a target object relative to a reference object after seeing 2-second videos simulating five conditions: static viewing, expansive optic flow, and lateral motion parallax in either continuous motion or image displacement. Ten participants viewed the stimuli with normal acuity in Experiment 1 and 11 with three levels of artificially reduced acuity in Experiment 2. Linear regression models represented the relationship between the depth estimates of participants and the ground truth. Lateral motion parallax produced more accurate depth estimates than expansive optic flow and static viewing. Depth perception with continuous motion was more accurate than that with displacement under mild and moderate, but not severe, acuity reduction. For observers with both normal and artificially reduced acuity, lateral motion parallax was more helpful for object depth estimation than expansive optic flow, and continuous motion parallax was more helpful than object image displacement.
Topics: Humans; Depth Perception; Optic Flow; Motion Perception; Motion; Retina
PubMed: 37801321
DOI: 10.1167/jov.23.12.3 -
Psychonomic Bulletin & Review Aug 2020Although spatial attention has been found to alter the subjective appearance of visual stimuli in several perceptual dimensions, no research has explored whether...
Although spatial attention has been found to alter the subjective appearance of visual stimuli in several perceptual dimensions, no research has explored whether exogenous spatial attention can affect depth perception, which is a fundamental dimension in perception that allows us to effectively interact with the environment. Here, we used an experimental paradigm adapted from Gobell and Carrasco (Psychological Science, 16[8], 644-651, 2005) to investigate this question. A peripheral cue preceding two line stimuli was used to direct exogenous attention to either location of the two lines. The two lines were separated by a certain relative disparity, and participants were asked to judge the perceived depth of two lines while attention was manipulated. We found that a farther stereoscopic depth at the attended location was perceived to be equally distant as a nearer depth at the unattended location. No such effect was found in a control experiment that employed a postcue paradigm, suggesting that our findings could not be attributed to response bias. Therefore, our study shows that exogenous spatial attention shortens perceived depth. The apparent change in stereoscopic depth may be regulated by a mechanism involving direct neural enhancement on those tuned to disparity, or be modulated by an attentional effect on apparent contrast. This finding shows that attention can change not only visual appearance but also the perceived spatial relation between an object and an observer.
Topics: Adolescent; Adult; Attention; Cues; Depth Perception; Female; Humans; Male; Vision Disparity; Young Adult
PubMed: 32319001
DOI: 10.3758/s13423-020-01724-9