Final answer:
A psychologist who emphasizes rewards and punishments to influence behavior is using the Behavioral approach, which is based on the tenets of behaviorism and was exemplified by B.F. Skinner's research on operant conditioning.
Step-by-step explanation:
The psychologist who emphasizes the power of rewards and punishments to influence behavior is most likely utilizing the Behavioral approach. This approach is rooted in behaviorism, which focuses on observable behaviors rather than internal thought processes or emotions. By using reinforcement (rewards) and punishment, the behaviorist aims to shape and control behavior. A classic example of this approach is the work of B.F. Skinner, who conducted extensive research on operant conditioning, showing how positive and negative reinforcement could be used to achieve desired behaviors.
The other approaches listed, such as the Cognitive approach, Humanistic approach, and Psychoanalytic approach, focus on different aspects of psychology. The Cognitive approach centers on mental processes like thinking and memory; the Humanistic approach emphasizes personal growth and self-actualization; and the Psychoanalytic approach focuses on unconscious motives and conflicts.