Space and time in masking and crowding

Lev, Maria; Polat, Uri

doi:10.1167/15.13.10

Cited by 51 publications

(95 citation statements)

References 131 publications

(333 reference statements)

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“…As previously mentioned, when investigating how time influences contrast sensitivity, we found an increase in contrast sensitivity as a function of the longer presentation time of the target for both normally sighted and IN subjects, consistent with previous studies 24,84 . However, whereas IN continued to improve in contrast sensitivity up to the longest presentation time of 480 ms in the poor eye, normally sighted subjects reached saturation at earlier times and under all conditions.…”

Section: Fusion Fusion Is a Clinical Condition That Can Affect Binocsupporting

confidence: 92%

Monocular and Binocular Temporal Visual Perception of Infantile Nystagmus

Moshkovitz

Lev

Polat

2020

Sci Rep

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duration, is defined as the point at which further stimulus presentation time does not contribute to enhanced performance 6,24. In some studies, critical duration refers to the time in which contrast sensitivity reaches 90% of the maximal value 24,25. Critical duration can be influenced by spatial and temporal parameters. Studies suggest that the period of temporal integration is affected by spatial frequency; the higher the spatial frequency is, the longer will be the time needed for integration 19. In the literature, the range of critical duration is between 160 and 200 19,26. In addition, critical duration can change as a result of cortical deprivation in cases such as amblyopia 27-31 or neurological disease 29. Nystagmus is a form of spontaneous oscillation of the eyes, which results in excessive motion of images on the retina, accompanied by poor vision including a reduction in visual acuity 32-35. In normal fixation, the eyes are not still; they move at a velocity of 3 minutes of arc in one second 36. Infantile nystagmus (IN) is accompanied by reduced vision in both eyes during the critical periods of life 37-39. The prevalence of infantile nystagmus is 1 to 1000-6000 34,35. The most common form of infantile nystagmus is afferent nystagmus; it is caused by impairment of central vision in early life, e.g., albinism or congenital cataract 35,40. Albinism is a heterogeneous group of congenital disorders affecting melanin synthesis. A few weeks after birth, nystagmus can appear in albino subjects 41. In research investigating nystagmus, albinos are one of the main participants 42-44. In addition, if efferent, it is an idiopathic nystagmus, without any involvement of ocular or systemic pathology. The onset is about 2-3 months after birth and it persists throughout life 45,46. In cases of nystagmus, contrast sensitivity is reduced 35,40,47-49. Vision impairment of cortical origin, such as amblyopia, is characterized by deficits in normal processing such as binocular summation and critical duration. In this study we investigated how binocular and monocular processing was affected in IN due to visual impairment. We hypothesized that in nystagmus, similarly to amblyopia, we would observe absent or diminished binocular summation from the two eyes, and that the critical duration differs from normal sighted vision.

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Section: Fusion Fusion Is a Clinical Condition That Can Affect Binocsupporting

confidence: 92%

Monocular and Binocular Temporal Visual Perception of Infantile Nystagmus

Moshkovitz

Lev

Polat

2020

Sci Rep

Self Cite

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“…It certainly appears that collinear facilitation (SM) is dependent on stimulus duration. At 3λ, Lev & Polat (2015) found no facilitation with a 30 ms stimulus duration. Cass & Spehar (2005) found little facilitation at 20 ms, but robust facilitation with a 40 ms stimulus duration.…”

Section: Discussionmentioning

confidence: 79%

“…In a recent comprehensive paper exploring the relationship between lateral masking and crowding, Lev & Polat (2015) suggest that participants with lower "contrast thresholds" (i.e. higher facilitation) may have longer integration times as a result of reduced levels of inhibition.…”

Section: Discussionmentioning

confidence: 99%

Individual differences in the dynamics of collinear facilitation?

2017

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Collinear facilitation refers to the increase in sensitivity found for a target when aligned between nearby, brighter flankers. Many studies have explored the spatial and temporal aspects of this arrangement, and there is a consensus that two mechanisms could be responsible for this phenomenon; lateral excitation within V1 and extra-striate feedback to V1. There is some debate as to whether facilitation can still occur if the target is presented before the flankers, a manipulation known as backward masking, which could rely on feedback to V1. We shed light on this debate by using forward, simultaneous and backward masking with a relatively large sample of 26 participants.We used short stimulus presentation times (35 ms) and a range of SOAs (stimulus onset asynchronies) (-70, -35, 0, 35 and 70 ms) in order to isolate any feedback facilitation that may occur.We found that collinear facilitation occurred with forward masking (+ve SOAs) in all participants.However, facilitation with backward masking (-ve SOAs) only occurred in 54% of participants. We present a basic model of facilitation that simulates the results of our experiment and could account for differences between previous studies. The model indicates that facilitation with backward masking arises primarily from feedback excitation. Our findings suggest that both lateral connectivity and extra-striate feedback contribute to target facilitation, but in fundamentally different ways and that feedback may be significantly reduced in some participants.2

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“…Masking refers to the reduction in visibility of a (target) stimulus when it is presented in close spatiotemporal proximity to another (mask) stimulus (Breitmeyer & Ogmen, 2006). Masking and crowding are affected similarly by certain spatiotemporal properties of the stimuli such as stimulus onset asynchrony and duration (Chung et al, 2001; Lev & Polat, 2015); however, they also have distinct characteristics (Chung et al, 2001; Pelli, Palomares, & Majaj, 2004). …”

Section: Introductionmentioning

confidence: 99%

Unmasking saccadic uncrowding

2016

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Stimuli that are briefly presented around the time of saccades are often perceived with spatiotemporal distortions. These distortions do not always have deleterious effects on the visibility and identification of a stimulus. Recent studies reported that when a stimulus is the target of an intended saccade, it is released from both masking (De Pisapia, Kaunitz, & Melcher, 2010) and crowding (Harrison, Mattingley, & Remington, 2013). Here, we investigated pre-saccadic changes in single and crowded letter recognition performance in the absence (Experiment 1) and the presence (Experiment 2) of backward masks to determine the extent to which saccadic “uncrowding” and “unmasking” mechanisms are similar. Our results show that pre-saccadic improvements in letter recognition performance are mostly due to the presence of masks and/or stimulus transients which occur after the target is presented. More importantly, we did not find any decrease in crowding strength before impending saccades. A simplified version of a dual-channel neural model, originally proposed to explain masking phenomena, with several saccadic add-on mechanisms, could account for our results in Experiment 1. However, this model falls short in explaining how saccades drastically reduced the effect of backward masking (Experiment 2). The addition of a remapping mechanism that alters the relative spatial positions of stimuli was needed to fully account for the improvements observed when backward masks followed the letter stimuli. Taken together, our results (i) are inconsistent with saccadic uncrowding, (ii) strongly support saccadic unmasking, and (iii) suggest that pre-saccadic letter recognition is modulated by multiple perisaccadic mechanisms with different time courses.

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Space and time in masking and crowding

Cited by 51 publications

References 131 publications

Monocular and Binocular Temporal Visual Perception of Infantile Nystagmus

Monocular and Binocular Temporal Visual Perception of Infantile Nystagmus

Individual differences in the dynamics of collinear facilitation?

Unmasking saccadic uncrowding

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