Training Older Adults to Improve Their Contrast Sensitivity: A Possible or Impossible Task?

Abstract

Contrast sensitivity (CS) refers to the visual ability to detect small luminance differences between objects and the background. Age-related decrement in CS is associated with increased accident risk for older drivers. A number of perceptual learning studies have demonstrated improved CS through training for young adults. However, there is no research that has examined the possibility of improving older adults' CS. In this study, fourteen older adults (M = 77.86, SD = 9.41) were trained with contrast-related tasks for three days in a darkened room. Subjects were assigned into two training groups, each of which practiced either a contrast discrimination task (CSD) or a Gabor orientation discrimination task (GOD). In each training group, about half participants received training under high luminance condition (50 cd/m²) while the other half were trained under low luminance condition (3 cd/m²). Each participant was strictly trained monocularly in one of the standard orientation (45° or 135°). Pre-training and post-training thresholds were measured for each observer in each eye (except one observer), and under each luminance condition for each of the four different tasks (contrast detection task, contrast discrimination task, Gabor orientation discrimination task, and line orientation discrimination task). After the training, significant improvements were shown for the trained task for six out of eight observers in GOD training group and three out of the six observers in CSD training group. More importantly, transferred learning effects were found across untrained conditions, e.g. eyes, luminance levels, and most tasks. Interestingly, for observers in GOD group the learning did not transfer to the untrained CSD task and for CSD group the learning did not transfer to the untrained line orientation discrimination task. Overall, the present study provides more evidence in support of neural plasticity in the aged brains. For older adults, contrast-related learning is more display-dependent than task-dependent.

WSU RIA Gridley Hoover Project.