Abstract
Previous research has shown transfer of perceptual learning (PL) training with contrast and orientation across different locations in the visual field (Xiao et. al., 2008). The current study examined the cross-transfer of PL training with orientation and contrast within a specific location in the visual field. Subjects were given 4 days of testing and PL training. A two interval forced choice procedure was used with two sequentially presented displays. On each display subjects were presented with a centrally located letter and a Gabor patch located in one quadrant (both embedded in noise). Subjects were required to indicate a change in the letter to control for eye fixation. The Gabor patch was orientated horizontally or vertically (the standard) or was tilted off horizontal or vertical. Subjects were required to indicate whether the first or second display contained the tilted orientation. All stimuli were presented with 40% of the pixels replaced with 2-dimensional Gaussian noise. During the first day participants' orientation discrimination (0-10 degrees off-axis in 0.25 degree increments) and contrast sensitivity (1-100% contrast) thresholds were determined using two interleaving staircase functions (1 up/4 down and 1 up/2 down) for vertically and horizontally oriented Gabor patches. During days 2 and 3, participants were trained on contrast sensitivity using two interleaving staircases (1 up/4 down and 1 up/2 down); during this training all Gabor patches were either oriented vertically or 10 degrees off axis. Day 4 used the same procedure as day one to assess contrast sensitivity and orientation discrimination thresholds. Results suggest that perceptual learning training resulted in improved performance for contrast for both the trained (vertical) and untrained (horizontal) orientations; the improved performance for contrast training was not found to transfer to orientation discrimination. The importance of these findings to task specificity of perceptual learning training will be discussed.
Research supported by NIH EY018334 and AG031941.