Reduced Monocular Luminance Increases Monocular Temporal Synchrony Threshold in Human Adults

Abstract

The purpose of this study was to present our investigation of the influence of reduced monocular luminance on monocular and dichoptic temporal synchrony processing in healthy adults. METHODS. Ten adults with normal or corrected to normal visual acuity participated in our psychophysical study. The temporal synchrony threshold in dichoptic (experiment 1), monocular (experiment 2), and binocular (experiment 3) viewing configurations was obtained from each observer. Four flickering Gaussian dots (one synchronous and one asynchronous pair of two dots) were displayed, from which the observers were asked to identify the asynchronous pair. The temporal phase lag in the signal pair (asynchronous) but not in the reference pair (synchronous) was varied. In addition, a neutral density (ND) filter of various intensities (1.3 and 2.0 log units) was placed before the dominant eye throughout the behavioral measurement. In the end, dichoptic, monocular, and binocular thresholds were measured for each observer. RESULTS. With decreasing monocular luminance, the dichoptic threshold (2 ND vs. 0 ND, P < 0.001; 2 ND vs. 1.3 ND P = 0.001) and monocular threshold (2 ND vs. 0 ND, P < 0.001; 2 ND vs. 1.3 ND, P = 0.003) increased; however, the bincoular threshold remained unaffected (P = 0.576). CONCLUSIONS. Reduced luminance induces delay and disturbs the discrimination of temporal synchrony. Our findings have clinical implications in visual disorders.

Temporal synchrony discrimination is abnormal in dichoptic but not monocular visual processing in treated anisometropic amblyopes

“…Similar to previous studies, 20,24 for the three psychometric functions from each observer, an F-test indicated that the full model (with different slopes across different configurations) and the reduced model (with the same slopes across different configurations) were not statistically different. Hence, we assumed that the psychometric slopes were equal across the three configurations for each observer.…”

“…A similar paradigm to previous studies 20,24,25 was used to measure the temporal synchrony threshold in this study. Two pairs of Gaussian dots were shown in the task: the reference pair flickered synchronously, while the signal pair flickered asynchronously.…”

A brief light reduction induces a significant delay in the previously dimmed eye

“…A brief light reduction induces a significant delay in the previously dimmed eye Seung Hyun Min 1,2 | Alexandre Reynaud 1 | Robert F. Hess 1 be demonstrated in visually impaired individuals due to anatomical or neural pathologies that produce interocular imbalances. For example, unilateral cataract reduces the light transmission through the affected crystalline lens.…”

“…However, the luminance level between the eyes has to be equal for optimal visual processing. Otherwise, binocular balance, 1 interocular temporal synchrony 2 and depth perception 3 are compromised. For example, the difference in the interocular light level can induce the Pulfrich effect, which is a century‐old illusion of depth in the absence of disparity 4 .…”