Investigates factors that have effects on conditioning. Tests nine mice with three types of reinforcement: (1) primary-need positive reinforcement; (2) secondary-need positive reinforcement; and (3) secondary-need negative reinforcement. Measures the effectiveness of the reinforcements by both rate of response and response strength. Discusses the effectiveness of the type of reinforcer, the type of reinforcement, and other unexpected factors on conditioning. (Author/KHR)