Classical Conditioning in Early Life: White Coats and Doctor Visits Most infants receive several vaccinations in their first few years of life. The painful injection (a UCS) elicits fear and distress (a UCR). After a few office visits, the clinic, nurse, or even the medical staff’s white lab coats can become a conditioned stimulus (CS) that elicits fear and distress—even in the absence of a painful injection.

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