An average of 5,600 practice trials were necessary to reach a
threshold of 80% accuracy in at least 10 consecutive blocks of
trials (see Fig. 1B for a representative psychophysical curve; see
Table S1 for individual results). Perceptual learning was specific
for the trained shape and trained quadrant, and did not generalize
to other quadrants and orientations (Fig. 1C). These
behavioral data confirm the well-known retinotopic and orientation
specificity of perceptual learning (23, 24).