The present study aimed at revealing the effect of antecedent cognitive incongruity on information reception and curiosity. The experimental design was modified from the previous one (Inagaki, 1970) in order to lead Ss to attend to the proper aspects of incongruity. Individual differences in achieving the correct concept under different types of motivating operations were also examined. Ninety-nine 6th graders served as Ss. Learning material was classification of animals, using that of monkeys and apes as an example. Three unfamiliar monkeys were presented as positive infirming instances and 3 familiar monkeys as positive confirming instances. The experiment consisted of two sessions: Pre-instruction test was given in the first session and immediate pre-test, Information 1, 2, 3, and Post-instruction test were administered in the second session. Information 1 described characteristics of 3 unfamiliar monkeys to experimental Ss and of 3 familiar monkeys to control Ss. Information 2 and 3 were constructed similarly to the previous experiment and were expected, respectively, to have latent and manifest incongruity-reducing character for the experimental Ss. After the presentation of each Information, Ss were questioned as to their cognitive curiosity. Immediate pre-test was given prior to presentation of Information 1 and was repeated after the presentation. This test consisted of items concerning classification criteria of monkeys. Not only could Ss' response tendency to adopt correct criteria (characteristic of structure and function of body formed by consequence of evolution) be revealed, but Ss' attention to the criteria of monkey classification could be focused on. Ss were also required to assess their certainty of their answers in this test. Furthermore they were encouraged to ask questions in a semi-forced situation after Information 2. The results were as follows: i) Information presented after cognitive incongruity had been aroused was received as having an epistemic character. Ss of the experimental group, who had experienced incongruity, showed better results (more correct respondents in number) in the item which required Ss to choose criteria of classification of monkeys and animals-in general (See Table 7, 9). They could apply and relate the general principle of classifying monkeys, which was presented in Information 3, to the specific instance of a monkey (Table 8). ii) Incongruity-arousing information (Information 1 to the experimental group) produced stronger cognitive curiosity than Information 1 to the control group (Table 1). There wan no statistically significant difference in curiosity aroused by incongruity- reducing informations (Informations 2 and 3), while the experimental group Ss showed a little stronger curiosity (Table 2). iii) There was no difference between groups concerning the number of questions asked in the semi-forced situations (Table 4). iv) When correlation coefficients were calculated between pre-experimental cognitive and noncognitive variables, post-exposure performance items, and cognitive uncertainty and curiosity generated by each Information under each condition, there were found two groups of items which were highly correlated to each other in both conditions. One group included intellectual readiness and performance items. The other included items concerning pre-experimental curiosity, uncertainty of one's response and curiosity to incongruity- reducing informations (Table 10).