Which conditioning occurs when the UCS (usually internal cues associated with nausea or vomiting) occurs several hours after the CS, leading to a strong CS-UCS association in a single trial (John Garcia)?

• A. Habituation
• B. Conditioned taste aversion
• C. Instinct
• D. Stimulus discrimination

Answer: (B)

Conditioned taste aversion is when a taste (the conditioned stimulus) becomes linked with illness (the unconditioned stimulus) and the taste alone elicits aversion. What makes this learning stand out is that it can form after just one pairing and even when the illness occurs several hours after the tasting. This long-delay, one-shot association was demonstrated by John Garcia with animals, showing that flavors linked to sickness can be avoided strongly after a single experience. The adaptation is practical: organisms learn to steer clear of foods that previously made them sick, reducing future risk. Other options describe different processes—habituation is a decreasing response to repeated exposure, instinct refers to inborn behaviors, and stimulus discrimination is about telling apart different stimuli—none capture the single-trial, long-delay link between taste and illness that defines conditioned taste aversion.