Abstract
Previous studies have found that detection of near-threshold stimuli can be improved with training (perceptual learning) (Karni & Sagi, 1991, PNAS). The goal of the present study was to determine whether perceptual learning of near/sub-threshold stimuli can occur with older observers. In the present study, we used a commonly used texture discrimination task (TDT) to assess perceptual learning. On each trial, observers were presented with a target item embedded in noise for 100msec, followed by a blank interstimulus interval, followed by a mask display for 10msec. The threshold of interest was SOA between target and mask. 15 older (mean age of 73) and 9 younger (mean age of 23) subjects participated in the study. Each subject was run through four blocks of training on two consecutive days (a total of 1152 trials). To assess learning the SOA threshold (85% accuracy) was assessed using a BEST-PEST procedure at the beginning (pre-test) and end (post-test) of each day. The SOA used in the training sessions was the 60% accuracy level based on each subject's psychometric function. The results showed that significantly greater perceptual learning occurred for older as compared to younger subjects. The results from a group of control subjects (who were not presented sub-threshold SOA conditions) indicated that the learning found for older subjects was not the result of repeatedly performing the discrimination task. These results suggest that perceptual learning can be used to improve perceptual performance of older subjects. The importance of these results to issues regarding the recovery of age-related declines in vision will be discussed.
This work was supported by NIH AG13419-06, NIH EY015980