Which statement describes sensitization?

• A. A reduced response to repeated exposure to a stimulus
• B. When a behavioural response is amplified by repeated exposure to a stimulus
• C. A change in memory due to sleep
• D. A random fluctuation in reaction

Answer: (B)

Sensitization is when a person or animal shows a stronger, more amplified response to a stimulus after repeated exposure. It’s a nonassociative learning process where the stimulus becomes more salient or arousing, so the reaction grows with each exposure. This is different from habituation, where the response weakens with repetition. For example, after an initially strong noxious stimulus, subsequent exposures can produce a heightened startle or reflex to the same or even related stimuli. The other options don’t fit: a reduced response describes habituation; a memory change due to sleep refers to sleep-dependent memory consolidation; a random fluctuation isn’t a systematic increase in response.