How does stimulus-response compatibility influence reaction time?

• A. Higher compatibility increases reaction time.
• B. Higher compatibility reduces reaction time.
• C. No effect of compatibility on reaction time.
• D. Compatibility only affects accuracy, not reaction time.

Answer: (B)

Stimulus-response compatibility describes how naturally a stimulus signals the appropriate response. When the mapping is compatible, perception and action align smoothly, so the brain can transform what you see into the correct movement with little extra processing. This direct mapping reduces interference and the time needed to select and initiate the response, leading to faster reaction times. If the mapping is incompatible, the brain faces a conflict: the stimulus triggers a different or opposite response, requiring extra inhibition and selection effort, which slows the reaction. So, as compatibility increases, reaction time tends to decrease.