Abstract
Visual perceptual learning of stimuli presented in the central visual fields, near the fovea to 20° eccentricities, occurs with many novel visual tasks. It was unclear, however, if the magnitude and rate of perceptual learning are similar across the central visual fields or if visual learning decreases with increasing eccentricity, like visual acuity and color vision. The robustness of perceptual learning across the central visual fields may affect the magnitude of computer-aided visual recovery after visual brain injury. Therefore we determined if eccentricity was a factor that influenced perceptual learning.
Subjects aged 21 to 29 years were trained to detect the presence or absence of a single line oriented differently (odd element) from an array of lines that otherwise had the same −30°orientation (Neary, Anand & Hotson, Experimental Brain Research 2005:162:23–34). The odd element was presented for 120 ms in 1 of 4 visual field quadrants 3°, 9° or 18° from fixation. Prior to training, an odd element orientation was selected that resulted in ∼ 60–70% correct responses. Pre- and post-training percentage correct responses without feedback were obtained. Each subject trained in a total of 2880 trials with feedback over multiple days.
Perceptual performance improved during training trials with a similar magnitude and similar learning curve slopes at all 3 eccentricities. Pre- and post-training performance improved to a similar magnitude at 3 vs. 9° in 4 of 4 subjects tested and at 9° vs. 18° in 4 of 5 subjects. In a fifth subject there was no post-training improvement in performance at 18°.
The magnitude and rate of perceptual learning is similar across the critical central visual fields in almost all young subjects. Subject performance variability may increase with eccentricity.