Behavioral control by an imprinted stimulus: long-term effects.

Scientists used baby ducklings that had imprinted on a moving object. The object became a reinforcer for key-pecking. They tracked how long the pecking lasted as the birds grew.

The team wanted to know if an imprinted stimulus could keep its power over many weeks. They ran a single-case lab design and watched burst patterns change with age.

The imprinted object kept the ducklings pecking for a long time. Response bursts shifted as the birds matured, but the behavior did not stop.

The study showed that early imprinted stimuli can serve as durable reinforcers in non-human animals.

Hoffman et al. (1966) set up the same key-peck preparation one year earlier. That paper proved the method works; the 1967 paper shows it keeps working as animals age.

Hoffman et al. (1969) extended the idea to feeding behavior. They found the imprinted stimulus can reinforce eating without ever being paired with food.

de Villiers (1980) later showed adult ducks can still imprint, while chickens cannot. Together these studies map both the long-term reinforcer power seen here and the lifelong plasticity ducks retain.

You now have lab proof that a single early-learned stimulus can drive operant behavior for weeks. When you pick reinforcers for clients, think about items that gained power during early favorite activities. Test if those "imprinted" items still work months later; they may save you from constant novelty searches.