Final answer:
B.F. Skinner became known as America's best-known living psychologist due to his research on operant conditioning and his development of the Skinner box.
Step-by-step explanation:
B.F. Skinner became known as America's best-known living psychologist through his research on operant conditioning and his development of the operant conditioning chamber, also known as the Skinner box. He focused on how behavior is affected by its consequences, specifically reinforcement and punishment. Skinner's work on behavior modification and his emphasis on the role of consequences in learning had a lasting influence in psychology.