The purpose of this experiment was to test the reward given in different orders-pre- and post-performance and performance without reward that would produce different effects on the performance of assignment. And this was simulated to the public functionary and the teachers in doing their job with extra pay would bring different results on their performance. 　　It was considered that the reward would bring about a better performance, and indirectly facilitate learning; however, all given the reward either pre or post the performance would make no significant difference between them. And it was found that the pre-reward group seemed better than the post-reward group in comparing with the non-reward group in speed and accurateness. This proved that the former group was stronger than the latter in incentive motivation. The difference between the reward and non-reward all depended on the kind of perfoamance. If the material for performance was a kind of association and contiguity, then there would be no differences among them. This was found in the test of word paired number association. However if the material was not a kind of association like accurateness of motor performance, then significant difference was found among the pre-reward and post-reward and the non-reward groups. This proved that accurateness was greatly affected by emotion and incentive motivation. As far as the speed was concerned, it seemed there was a kind of learning between contiguity and reinforcement. Furthermore, it was found association and speed would be improved by practice significantly; however, accurateness was not so, the errors of non-reward group were increasing (p<0.01). Therefore in the theory of Spence' excitatory potential [E = H (0+ K)] under the assigned job, the effect of reward had to be considered with the kind of learning that was performed.