This study compares the effectiveness of 3 patterns of motivation - reward for desired behavior, punishment for undesired behavior, reward for desired behavior with punishment for undesired behavior. Subjects were 70 women and 52 men between the ages of 17 and 18, students of secondary school. They were randomly divided into 4 groups, 3 experimental and one control (no reinforcement applied). An experiment was designed in which the rewards and punishments administered were of the nature of information supplied to subjects on their success or failure in solving the experimental tasks. The consequences of success and failure were differentially pleasant or unpleasant for students. Statistical analysis of the results of permit the following conclusions: 1. Reward is more effective than punishment for human behavior modification. 2. Reward for desired behavior with punishment for undesired behavior is less effective than reward for desired behavior.