The present study aimed at investigating developmental changes in cognitive strategy for concept learning. Ss were required to identity the criteria of concepts and to classify a set of stimuli, utilizing information transmitted by positive or negative instances. A modified and objectively defined procedure crf Vygotsky-type concept formation experiment was undertaken. Variable dimensions of 22 stimuli were size (2 values), form (6), color (5) and the presence of a frame (2). These 22 stimuli could be classified into 4 categories according to their values on relevant dimension size and frame.