Impaired visual decision-making in individuals with amblyopia

Abstract

This study examined the effects of amblyopia on perceptual decision-making processes to determine the consequences of visual deprivation on development of higher-level cortical networks outside of visual cortex. A variant of the Eriksen flanker task was used to measure response time and accuracy for decisions made in the presence of response-selection conflict. Performance of adults with amblyopia was compared to that of neurotypical participants of the same age. Additionally, simple and choice reaction time tasks presented in the visual and the auditory modality were used to control for factors such as feature visibility, crowding, and motor execution speed. A selective deficit in response time for visual decisions was found when individuals with amblyopia used either the amblyopic or non-amblyopic (dominant) eye, and this deficit was independent of visual acuity, motor time, and performance accuracy. In trial conditions that provoked response-selection conflict, responses were significantly delayed in amblyopic relative to neurotypical participants, and were not subject to standard trial sequence effects. Our results indicate that, beyond the known effects of abnormal visual experience on visual cortex, suboptimal binocular input during a developmental critical period may also impact cortical connections to downstream areas of the brain, including parietal and frontal cortex, that are believed to underlie decision and response-selection processes.

Covert spatial attention is functionally intact in amblyopic human adults

“…They found that amblyopes significantly underestimated the number of targets when using their amblyopic eye compared to the nonamblyopic eye and controls across all cueing conditions, which they argue to be evidence for a “high-level deficit.” Note that even though their amblyopes do exhibit a robust and reliable endogenous attention effect (valid vs. invalid cueing) of the same magnitude as that shown by visually intact observers, this study is often cited as one of the primary studies providing evidence for a visual attention deficit in amblyopia (Farzin & Norcia, 2011; Ho et al, 2006; Hou et al, 2016; Levi, 2013; Levi & Tripathy, 2006; McKee, Levi, Schor, & Movshon, 2016; Secen et al, 2011; Tripathy & Levi, 2008). …”

Saccadic latency in amblyopia

“…Because the amblyopic eye does not determine the saccadic target, it probably has little influence on selective attention during binocular viewing, and may suffer from inadequate command of attention even during monocular viewing. Several studies have found abnormalities in the control of attention by the amblyopic eye (Farzin & Norcia, 2011; Kiorpes, Pham, & Carrasco, 2012; Popple & Levi, 2008; Sharma, Levi, & Klein, 2000). Lai, McKee, Hou, and Verghese (2013) found that the amblyopic eye could use cued attention to enhance contrast sensitivity, but that the shift in attention to the cued site was delayed, compared to normal observers.…”

Stereopsis and amblyopia: A mini-review

“…Recent work suggests that the amblyopic deficit is then amplified downstream (Levi, 2006; Muckli et al, 2006). Thus amblyopes suffer not only from sensory deficits, but also from deficits not simply explained by low-level considerations (Farzin & Norcia, 2011; Kiorpes, 2006; Levi, 2006; Sharma, Levi, & Klein, 2000). These include second-order processing, contour integration, and temporal, spatial and/or capacity limits of attention.…”