Conditioned suppression and variable ratio reinforcement.
High VR schedules can mask conditioned suppression, so behavior looks unaffected by warnings or mild punishers.
01Research in Context
What this study did
O and team worked with rats pressing a lever for food.
They used variable-ratio (VR) schedules. The rats had to press 50, 100, or 200 times to earn one pellet.
While the rats worked, a short tone came on. At tone offset, the rats got a mild foot-shock. The researchers watched how much the tone slowed lever pressing.
What they found
Even the weakest VR 50 schedule kept the rats pressing fast. The tone only slightly cut response rate.
When the requirement rose to VR 200, pressing slowed a little more, but the drop stayed small.
High VR rates acted like a shield; the warning signal barely suppressed behavior.
How this fits with other research
Two years later, Zeiler (1968) ran almost the same setup. That study showed the opposite: high response rates made the tone stop more behavior, not less.
The difference is simple. Lyon et al. (1966) kept shock intensity the same for every VR size. Zeiler (1968) lowered the shock for fast responders. Smaller shock equals bigger suppression, so the later paper uncovered the true rule: lean, fast schedules amplify conditioned suppression when shock is adjusted.
M et al. (1978, 1981) also show that changing reinforcer size or drug dose shifts response rate on variable schedules. Together, the papers tell us that both reinforcer size and aversive intensity must be watched when we pick a schedule.
Why it matters
If you use high-rate schedules like VR during assessment, know that problem behavior may look "suppression-proof." The schedule itself can hide sensitivity to warnings or mild punishers. Before you say "this kid doesn’t react," check your reinforcement density and your consequence intensity. Try thinning the ratio or raising the punisher magnitude; the true effect may then show up.
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Join Free →Next time you run a VR program, briefly probe for suppression with a mild punisher or S-delta; if nothing changes, lower the ratio or raise the punisher intensity and probe again.
02At a glance
03Original abstract
Conditioned suppression is a decrease in response rate during a relatively short duration stimulus that terminates independently of the animal's behavior and coincidentally with a brief unavoidable shock. The degree of conditioned suppression was measured for each of three birds on three variable ratio schedules; that is, the number of responses required for food reinforcement was varied around a mean of 50, 100, or 200. The results indicated a slight and possibly negligible decrease in the degree of suppression as the mean number of responses required on the schedule was increased from 50, to 100, and 200. In general, it was found that all of the variable ratio schedules tested were quite insensitive to the conditioned suppression procedure, although almost complete suppression was obtained on a few occasions. Since the reinforcement was contingent upon the emission of responses, the birds typically displayed a high rate of response during the pre-shock stimulus on all schedules. In addition, the rate during the pre-shock stimulus often changed abruptly independent of the presentation of a reinforcement. As a result of the high rate of response and the abrupt changes in rate, the degree of suppression from trial to trial was quite variable. A clear analysis of an experimental variable on this baseline is thus difficult.
Journal of the experimental analysis of behavior, 1966 · doi:10.1901/jeab.1966.9-245