Perceptual learning on simple perceptual tasks is interpreted as plasticity of neuronal populations in the sensory cortex (M. Fahle & T. Poggio, 2002). The authors examined individual differences on perceptual learning for 2 tasks-inspection time (IT) and a motion direction discrimination task that was instantiated as random dot kinematograms. The authors' main questions were whether individual differences in perceptual learning were consistent across the 2 tasks and whether perceptual learning correlated with cognitive abilities test scores. In all, 56 young adults completed 16 threshold estimations on 1 of 2 orthogonal versions of each task. Then, the authors made 2 further threshold estimations for the untrained, orthogonal version. Participants also completed a battery of 6 cognitive abilities tests that measured fluid ability (Gf) and perceptual speed (Gs). Perceptual learning was demonstrated for both tasks, but the degree of learning across tasks was not characteristic of the individual. Learning on IT correlated with Gs (r = .35), but learning on the motion direction discrimination task was unrelated to cognitive ability. Correlations of IT with cognitive measures were stable over the training period. IT was correlated with both the motion direction discrimination task (r = -.39) and an unmasked line length judgment task (r = -.31). The authors concluded that perceptual learning on IT correlates with cognitive abilities test scores, that correlations of IT with cognitive abilities test scores are stable as task performance improves with practice, and that the IT task is psychologically complex.