According to Watson's behaviorism, psychology should study:

• A. Mental processes directly
• B. Stimulus and behavior, not mental processes
• C. Inner experiences through introspection
• D. Neurological mechanisms exclusively

Answer: (B)

Watson’s approach treats psychology as the science of observable behavior, focusing on the relationship between environmental stimuli and the organism’s responses. The key idea is that behavior can be measured and studied objectively, while internal mental states—thoughts, feelings, or conscious experiences—aren’t directly observable and thus aren’t suitable subjects for scientific study in this framework. By concentrating on stimulus–response relationships, psychology becomes the study of how the environment shapes behavior.

The other ideas imply directly studying mental processes, introspection, or neurological mechanisms in isolation. Watson argued that those inner experiences aren’t accessible or reliable for scientific analysis, whereas observable stimuli and behaviors provide a verifiable basis for psychological research.