Abstract

Perceptual learning (PL) is defined as the improvement in perceptual judgments as a function of controlled practice or training. The ability to discriminate different physical attributes of the stimulus correlates with behavioral improvements when the task involves discrimination of simple stimulus belonging to broader categories, -in terms of their contextual significance., has not been thoroughly characterized, Accordingly, we designed a “same/different” visual discrimination task using a category of kanji characters 817-18 strokes) that results in perceptual learning. Ten subjects were trained with a set of 30 characters for 9 sessions. The following session, we tested the transfer of discrimination skills to new items of trained category and elements of the non-trained category (kanji. We recorded the subject’s response and the reaction time. Our results show that 60% of the performance improvement (d’) on the perceptual skills is specific to the trained category indicating perceptual learning, 30% correspond to procedural learning and 10 % to explicit memory. Moreover, during the training sessions there is an initial improvement in the discrimination for both stimulus pairs (same/different), followed by a differential improvement for the discrimination of “different” stimuli. The differential improvement in performance can be explained by a specific shift in response preference towards the “different” option. The reaction times systematically decrease during training and remain stable for novel “different” stimuli but significantly increase for novel “same” stimuli and the shift in behavioral preference reflect a perceptual separation of the elements in the trained category.