Reaction time is best defined as?

• A. The time from stimulus onset to completion of action.
• B. Time of sudden onset of stimulus and the beginning of a response.
• C. Time from the onset of movement to its completion.
• D. Time from movement end to feedback.

Answer: (B)

Reaction time is the time from when a stimulus appears to the start of the response. This interval captures how quickly you perceive, decide, and prepare to move, before any actual movement occurs. The option that matches this definition describes the duration from stimulus onset to the beginning of the response, which is exactly the reaction time. The other descriptions refer to later stages, such as the movement itself (movement time) or what happens after the movement ends (feedback processing), which are not part of reaction time.