Age-related changes in low and midlevel vision: assessing the information degradation and neural inhibition accounts

Advancing age is accompanied by several changes to the visual system. In addition to physical/optical changes to the lenses’ flexibility and opacity, healthy aging also coincides with neuronal changes. Two prominent models attribute the latter either to a reduction in neural inhibition or to an increase in neural noise. In a sample of 40 normal-sighted participants (aged 42.6 14.3 years), we assessed visual acuity (VA), contrast sensitivity, masking, crowding, and grouping. While losses in acuity and contrast sensitivity would lead to subsequent reduction in overall processing efficiency, as predicted by the information degradation hypothesis; masking, crowding, and grouping involve processing of multiple features and could be more subject to changes in neural inhibition (Monge & Madden, 2016 Neurosci Biobehav Rev. 69 166–173). All measures of spatial resolution (near and far VA, and peak and cutoff spatial frequency) were found to be reduced with age. These spatial measures of information degradation, as well as advancing age also translated to increased baseline contrast thresholds for target detection, orientation discrimination, and feature integration in the masking, crowding, and grouping tasks. Similarly, they coincide with an increase in the distance over which flankers interfered with target detection and discrimination. Hence, we found that ageing leads to a degradation of the visual information in the form of reduced spatial resolution and efficiency of contrast processing, which coincides with an increase in the distance over which flankers interfere with target detection and discrimination. This is largely in line with the predictions from the information degradation hypothesis