Final answer:
B.F. Skinner's work laid the foundation for the study of behavior modification, focusing on how behavior is influenced by consequences.
Step-by-step explanation:
The psychologist whose work laid the foundation for the study of behavior modification is B.F. Skinner. Skinner was a behaviorist who focused on how behavior is influenced by its consequences, such as reinforcement and punishment. He conducted research on operant conditioning and developed the concept of the Skinner box to study behavior modification.