Abstract
Perceptual learning has been established as a method for improved visual perception and for the study of visual processes. While early studies, using the backward-masked texture discrimination task (TDT) focused on the location specificity effect and on the lack of transfer of the learned task, recent TDT studies used conditions that were considered to eliminate sensory adaptation (‘dummy paradigm’) showing the transfer. It was suggested that inhibitory processes triggered by adaptation and spatio-temporal context (masking) reduce learning efficiency. The reduced efficiency suggests that TDT learning is limited by non-texture tasks such as backward masking (BM). Here, we address this issue using the TDT method with different adaptation levels (determined by stimulus duration and repetition), and with pre/post-tests of BM. Standard TDT learning showed the typical threshold improvements (threshold SOA: 131ms to 95ms, 4 days, delta=36±8, mean ±SEM, N=6). BM pretests (Gabor target at fixation, BM, masks 2 Gabor flankers, ISI= 80-240ms) before standard TDT (high adaptation) training improved initial TDT thresholds (first session threshold 111.5±12.1ms vs 131±4.44ms, with and without BM pretests, respectively). BM pretests did not affect TDT initial thresholds in conditions with reduced adaptation (88ms±7.2 vs 82ms±14.3). Importantly, standard TDT training (high adaptation) reduced effective BM duration from 147ms to 101ms (delta=46±11, N=5), while reduced adaptation TDT training had no significant effect on BM duration (179ms vs 190ms, delta=-11±5, N=5). Our results suggest that learning generalization across experimental conditions and tasks depends on shared visual processes, here dominated by inhibitory effects involved in adaptation and masking. Interestingly, increased adaptation, due to increased stimulus duration or stimulus consistency, enabled transfer learning across tasks. The reduced BM effect after TDT training suggests decreased task-independent inhibitory processes due to training.