Positive conditioned suppression: conditioned suppression using positive reinforcers as the unconditioned stimuli.

Researchers placed lab rats on a steady lever-press schedule for food. A short tone came on before extra food, water, or mild brain stimulation arrived for free.

The team then counted lever presses during the tone. They wanted to know if a cue for good things, not bad, could still slow responding.

Response rates dropped when the tone sounded. Free goodies acted like mini 'time-outs' and suppressed the ongoing operant, much like a shock warning would.

The effect held across food, water, and brain stimulation, showing the drop was not tied to one reinforcer type.

Smith et al. (2010) later added a brief signal to each free reinforcer and saw even faster, deeper suppression. Their work extends the 1969 finding: a signal sharpens the pause that noncontingent rewards already create.

Rees et al. (1967) used the same lever-press baseline but paired the tone with nalorphine, a mild aversive. Both studies show suppression, proving the procedure detects either pleasant or unpleasant upcoming events.

Blue et al. (1971) showed shock-paired tones suppress key pecking even though pecking was never punished. The 1969 paper mirrors this: the drop is a conditioned emotional reaction, not a response-cost side effect.

If you run noncontingent reinforcement to reduce problem behavior, remember that the cue itself can become a brief 'brake.' Watch for momentary drops in appropriate responding when the NCR signal comes on. To keep skill behaviors going, consider shortening the signal or delivering the reinforcer contingent on the target response instead of free.