Stimulus control in the goldfish after massed extinction.

Researchers worked with goldfish in a tank. They first taught the fish to poke a light for food.

Next they turned the light off and watched the fish stop poking. Some fish got a surprise food pellet now and then. Others got nothing.

Fish that saw an odd pellet during extinction learned the difference faster. They poked only when the light was on.

Fish that got zero food kept poking at dim lights. Their stimulus control stayed fuzzy.

Snapper et al. (1969) ran the same test with pigeons. They also saw sharper control when birds could tell S+ from S-.

Powell et al. (1968) added extra training days. More days made the gradient even steeper, backing up the dose idea.

Sailor (1971) later showed that sharp control protects against hunger swings. The birds kept choosing correctly even when very hungry.

Mix a few reinforcers into extinction to clean up stimulus control. You will see fewer mistakes to similar cues. Try it when fading prompts or thinning schedules. One extra treat every minute or two can lock in the right response.