Factors influencing inhibitory stimulus control: differential reinforcement of other behavior during discrimination training.

Weisman (1970) asked a simple question. Can a DRO schedule turn a neutral cue into a stop signal?

Pigeons first pecked on a plain VI schedule. No difference between the two key colors.

Then the team switched one color to DRO. Pecks during this color now reset the timer.

Response rate in the DRO color dropped fast. The same birds now treated that color as a strong S-.

Even though total food per hour stayed equal, the birds learned when not to peck.

Pliskoff et al. (1972) ran a near-copy study but used DRH instead of DRO. Their pigeons pecked more in the unchanged VI, showing positive contrast. G’s birds pecked less, showing negative contrast. Same lab setup, opposite direction.

Lyons (1995) tutorial lists both papers. It says stimulus disparity controls the size of contrast. G proves the schedule itself is the disparity.

Mello (1966) showed punishment needs clear S- training to work. G shows DRO alone can build that S- without any punishment.

You can create a stop signal without cutting reinforcement. Just switch the schedule to DRO while keeping food rate the same. The learner will quickly learn which stimulus means "hands off." Use this when you need clean inhibitory control but want to stay at full reinforcement density.