Near-optimal combination of disparity across a log-polar scaled visual field

Maiello, Guido; Chessa, Manuela; Bex, Peter J.; Solari, Fabio

doi:10.1371/journal.pcbi.1007699

Cited by 18 publications

(48 citation statements)

References 93 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A potential approach to test this hypothesis would be to extend our model to be image computable, i.e., able to derive the constraints on grasp selection directly from images of the objects. If the image processing stages of model were designed to mimic those of the human visual system (e.g., Chessa et al, 2016 ; Maiello et al, 2020 ) we might then expect the model to begin making the same misjudgments as human participants.…”

Section: Discussionmentioning

confidence: 99%

Humans Can Visually Judge Grasp Quality and Refine Their Judgments Through Visual and Haptic Feedback

et al. 2021

Self Cite

View full text Add to dashboard Cite

How humans visually select where to grasp objects is determined by the physical object properties (e.g., size, shape, weight), the degrees of freedom of the arm and hand, as well as the task to be performed. We recently demonstrated that human grasps are near-optimal with respect to a weighted combination of different cost functions that make grasps uncomfortable, unstable, or impossible, e.g., due to unnatural grasp apertures or large torques. Here, we ask whether humans can consciously access these rules. We test if humans can explicitly judge grasp quality derived from rules regarding grasp size, orientation, torque, and visibility. More specifically, we test if grasp quality can be inferred (i) by using visual cues and motor imagery alone, (ii) from watching grasps executed by others, and (iii) through performing grasps, i.e., receiving visual, proprioceptive and haptic feedback. Stimuli were novel objects made of 10 cubes of brass and wood (side length 2.5 cm) in various configurations. On each object, one near-optimal and one sub-optimal grasp were selected based on one cost function (e.g., torque), while the other constraints (grasp size, orientation, and visibility) were kept approximately constant or counterbalanced. Participants were visually cued to the location of the selected grasps on each object and verbally reported which of the two grasps was best. Across three experiments, participants were required to either (i) passively view the static objects and imagine executing the two competing grasps, (ii) passively view videos of other participants grasping the objects, or (iii) actively grasp the objects themselves. Our results show that, for a majority of tested objects, participants could already judge grasp optimality from simply viewing the objects and imagining to grasp them, but were significantly better in the video and grasping session. These findings suggest that humans can determine grasp quality even without performing the grasp—perhaps through motor imagery—and can further refine their understanding of how to correctly grasp an object through sensorimotor feedback but also by passively viewing others grasp objects.

show abstract

Section: Discussionmentioning

confidence: 99%

Humans Can Visually Judge Grasp Quality and Refine Their Judgments Through Visual and Haptic Feedback

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…The results of Experiment 1 with sparse stimuli are consistent with the existence of a similar mechanim in humans. Standard energy models of disparity coding (28–30) utilise phase or position-shifted receptive fields in which maximum phase disparity and therefore maximum stereo acuity occurs along the horizontal axis. Off-axis phase disparities are also present and can contribute to sterescopic judgments (28,31), but are at lower disparity.…”

Section: Discussionmentioning

confidence: 99%

Stimulus-dependent depth constancy during head tilt

Skerswetat

Caoli

Bex

2022

Preprint

View full text Add to dashboard Cite

Stereopsis is traditionally measured with noise-based stereo tests while the observer views the test in primary gaze. We investigated the effect of stimulus sparseness and axial variations of interocular disparity induced via head rotations.First, we measured stereoacuity using a 4-Alternative-Forced-Choice (4-AFC) task with three uncrossed and one crossed disparity bandpass-filtered circles on a passive-3-D-monitor. Ten binocularly-normal adults fixated a central cross and clicked on the circle withcrossed disparity for forty trials/condition. Observers adopted head tilts of 0° or ±20° pitch, roll, or yaw, enforced with an innertial measurement unit and fixation enforced with an eye tracker. Next, we measured stereoacuity in 8 adults while either the head (H), monitor (M), or both (B) were tilted 0°, ±22.5°, or ±45° roll in random order (eighty trials/condition) using a 4-AFC task and random-dot stimuli. Head tilts did not signifcantly alter stereoacuity using narrow-band stimuli(p>0.05), despite that IPDs and the axis of disparity were differentially affected by the tilts. However, for random dot stimuli, stereoacuity decreased with increasing orientation difference between the head and monitor (H and M: p<0.05; B: p>0.05].Head tilt decreases IPD and rotates the axis of interocular disparity, however, these manipulations affect stereoacuity when measured with noise stimuli but not with sparse stimuli. The results are consistent with a vestibular input to stereoscopic disparity processing that can be detected by sparse stimuli but is masked by dense stimuli. The results have implications for natural vision and for clinical screening in patients with abnormal head posture.Significance statementDepth perception is a critical feature of human vision and it is thought that the ability to perceive stereoscopic depth is bound to an essentially eye-fixed, horizontal disparity of each image that rapidly deteriorates away from that limited horizontal axis. In a set of head tilt experiments, we varied the orientations of stereoscopic images and demonstrate that stereoacuity remains constant when deploying sparse narrow-band stimuli, and only worsens when using fine-detailed noise stimuli that mask off-axis disparities. These results shine new light upon the debate of neuroplasticity of stereo vision. Moreover, the results are consequential for diagnosis and treatment in people with atypical head- and eye alignment, such as for patients with torticollis or strabismus.

show abstract

“…The cross talk of the dichoptic system was 1% measured with a Spectrascan 6500 photometer. Eye movement data were successfully recorded through the shutter glasses, as in previous work 93 , 102 – 104 . Observers were seated at a viewing distance of 60 cm from the display, with head position stabilized using a chinrest.…”

Section: Methodsmentioning

confidence: 99%

A dichoptic feedback-based oculomotor training method to manipulate interocular alignment

Caoli

Sabatini

Gibaldi

et al. 2020

Sci Rep

Self Cite

View full text Add to dashboard Cite

Strabismus is a prevalent impairment of binocular alignment that is associated with a spectrum of perceptual deficits and social disadvantages. Current treatments for strabismus involve ocular alignment through surgical or optical methods and may include vision therapy exercises. In the present study, we explore the potential of real-time dichoptic visual feedback that may be used to quantify and manipulate interocular alignment. A gaze-contingent ring was presented independently to each eye of 11 normally-sighted observers as they fixated a target dot presented only to their dominant eye. Their task was to center the rings within 2° of the target for at least 1 s, with feedback provided by the sizes of the rings. By offsetting the ring in the non-dominant eye temporally or nasally, this task required convergence or divergence, respectively, of the non-dominant eye. Eight of 11 observers attained 5° asymmetric convergence and 3 of 11 attained 3° asymmetric divergence. The results suggest that real-time gaze-contingent feedback may be used to quantify and transiently simulate strabismus and holds promise as a method to augment existing therapies for oculomotor alignment disorders.

show abstract

Near-optimal combination of disparity across a log-polar scaled visual field

Cited by 18 publications

References 93 publications

Humans Can Visually Judge Grasp Quality and Refine Their Judgments Through Visual and Haptic Feedback

Humans Can Visually Judge Grasp Quality and Refine Their Judgments Through Visual and Haptic Feedback

Stimulus-dependent depth constancy during head tilt

A dichoptic feedback-based oculomotor training method to manipulate interocular alignment

Contact Info

Product

Resources

About