Is improved contrast sensitivity a natural consequence of visual training?

Abstract

Many studies have shown that training and testing conditions modulate specificity of visual learning to trained stimuli and tasks. In visually impaired populations, generalizability of visual learning to untrained stimuli/tasks is almost always reported, with contrast sensitivity (CS) featuring prominently among these collaterally-improved functions. To understand factors underlying this difference, we measured CS for direction and orientation discrimination in the visual periphery of three groups of visually-intact subjects. Group 1 trained on an orientation discrimination task with static Gabors whose luminance contrast was decreased as performance improved. Group 2 trained on a global direction discrimination task using high-contrast random dot stimuli previously used to recover motion perception in cortically blind patients. Group 3 underwent no training. Both forms of training improved CS with some degree of specificity for basic attributes of the trained stimulus/task. Group 1's largest enhancement was in CS around the trained spatial/temporal frequencies; similarly, Group 2's largest improvements occurred in CS for discriminating moving and flickering stimuli. Group 3 saw no significant CS changes. These results indicate that CS improvements may be a natural consequence of multiple forms of visual training in visually intact humans, albeit with some specificity to the trained visual domain(s).

Limited Restoration of Contrast Sensitivity with Training after V1 Damage in Humans

“…When developing therapeutic tools, it is equally important to define functions that can and cannot be restored and understand why. Although adaptive-contrast training improves CS for direction and orientation discrimination in visually intact humans (Levi et al, 2015;Xi et al, 2020), we now report its failure to restore normal CS in V1 stroke patients. Instead, it improved CS similarly to training with high-contrast stimuli (Huxlin et al, 2009;Das et al, 2014;Saionz et al, 2020).…”

“…Here, we asked if training with 1 cpd contrast-varying Gabors altered the qCSF at untrained SFs. The qCSFs measured in the intact fields of CB patients were comparable to those measured in young, visually intact controls (Levi et al, 2015), as well as in the intact field of CB patients (Das et al, 2014). Importantly, here we used similar stimulus parameters (size, SF and TF, eccentricity) and discrimination tasks as in those two studies.…”

“…Importantly, here we used similar stimulus parameters (size, SF and TF, eccentricity) and discrimination tasks as in those two studies. Training with high-contrast, random dot stimuli improved CS for discriminating low-SF drifting gratings in both CB (Huxlin et al, 2009;Das et al, 2014;Saionz et al, 2020) and visually intact (Levi et al, 2015) humans. Similarly, we saw significant changes in qCSF at low SFs (0.6-1 cpd) for motion discrimination in both subacute and chronic participants.…”

Contrast sensitivity: a fundamental limit to vision restoration after V1 damage

“…Here, we asked if training with 1cpd contrast-varying Gabors altered the qCSF at untrained SFs. Training with high-contrast, random dot stimuli improves CS for discriminating low-SF drifting gratings in both CB (Das et al, 2014; Huxlin et al, 2009; Saionz et al, 2020) and visually-intact (Levi et al, 2015) humans. Similarly, we saw significant changes in qCSF at low SFs (0.6-1cpd) for motion discrimination in both SA and CH participants.…”

What is new in perceptual learning?

“…Based on clinical examples, Levi, Shaked, Tadin, and Huxlin (2015) showed that with a standard learning Citation: Herzog, M. H., Cretenoud, A. F., & Grzeczkowski, L. (2017). What is new in perceptual learning?…”