Abstract
Previous research has shown aging causes decrements in orientation discrimination (Betts, Sekuler, & Bennett, 2007). Perceptual learning (PL) training may be a possible intervention to counteract these declines. One primary concern in PL is that of specificity and transfer. PL studies have shown transfer with contrast and orientation across different locations in the visual field (Xiao et al., 2008). The current study examined the transfer of PL training of orientation in younger (mean age 21.3, range 19–26) and older individuals (mean age 72.3, range 69–76). Eight younger and eight older subjects were given 4 days of testing and 3 days of PL training. A two interval forced choice procedure was used with two sequentially presented displays. On each trial subjects were presented with a centrally located Gabor patch oriented 40 degrees clockwise or counterclockwise off vertical (the standard) followed by a patch tilted clockwise or counterclockwise off the standard. Subjects were required to indicate whether the second display was tilted clockwise or counterclockwise off the standard. Participants were tested using a no noise condition and with 4 other levels of 2-dimensional Gaussian noise. Thresholds were determined using two interleaving staircase functions for their trained and untrained standards tested on separate days. During days 3, 4 and 5, participants were trained based on their previous performance in a no noise condition and a medium noise condition on their trained standard. Days 1, 2, 6 and 7 used the same procedure to assess orientation discrimination thresholds. Results indicate that PL training resulted in internal additive noise reduction and external noise exclusion, with older participants showing greater learning than younger participants. The improved performance in older participants was found to transfer to the untrained orientation. The importance of these findings to specificity, aging and the mechanisms of PL will be discussed.
Research supported by NIH EY0018334 and AG031941.