Variable-interval punishment during variable-interval reinforcement.
Punishment must hit 0.6 mA to stop VI behavior, and lighter settings plus leaner schedules speed recovery.
01Research in Context
What this study did
Filby et al. (1966) tested how mild electric shocks change behavior that is already earning food. Rats pressed a lever on a variable-interval food schedule. The team then layered on the same variable-interval schedule of brief shocks. They tried different shock strengths to see which ones stopped the lever pressing.
The researchers wanted to know two things. First, what shock level completely stops the behavior? Second, how fast does the rat return to normal pressing once the shocks end?
What they found
Only the strongest shock, 0.6 mA, fully stopped the lever pressing. Weaker shocks did almost nothing. After the shocks ended, the rats bounced back quickly if the shocks had been weak or delivered on a lean schedule. Strong shocks on rich schedules slowed recovery.
In short, punishment must reach a clear intensity threshold to work, and recovery is gentler when both the shock and the schedule are mild.
How this fits with other research
Fontes et al. (2025) now say the old "direct-suppression" story is too simple. Using rapidly shifting reinforcement rates, they show that animals pay attention to relative, not absolute, punishment levels. Their data update and supersede the 1966 intensity-only view.
Santi (1978) extends the finding to two-component schedules. Shocks suppress the lean component more than the rich one, confirming that reinforcement rate matters as much as shock strength.
Henton (1972) adds a twist: the same shock can either maintain or suppress behavior depending on the schedule. Under VI it suppresses, but under fixed-ratio-1 it can maintain responding. The schedule, not the shock itself, decides the outcome.
Why it matters
When you add a punisher, check both intensity and the reinforcement background. A mild punisher on a rich schedule may do nothing, while the same punisher on a lean schedule can bite. Plan for faster recovery by starting with lower intensity and thinner reinforcement. If the client’s behavior is maintained by dense reinforcement, raise the punisher or thin the schedule first. Track recovery data after you remove the punisher; it tells you whether your levels were appropriate.
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Join Free →Record the current reinforcement rate for the target behavior, then test a brief mild punisher while thinning reinforcement; if no suppression occurs within two sessions, raise intensity or further thin the schedule.
02At a glance
03Original abstract
Variable-interval punishment was superimposed on a variable-interval food reinforcement baseline for three groups of rats. The value for the variable-interval punishment schedule was the same as that for the variable-interval food reinforcement schedule, although the two schedules were programmed independently. The three groups were Variable Intervals 0.5, 1, and 3 min. Little or no suppression occurred in the three groups at mild (0.2 and 0.4 ma) intensities of punishment, but at 0.6 ma, complete suppression occurred almost uniformly. During continued punishment, there was no consistent recovery toward the pre-punishment baseline at suppressing intensities of punishment. After punishment was discontinued, recovery from suppression was more rapid the lower the punishment intensity, and the lower the value of the variable-interval schedules of reinforcement and punishment.
Journal of the experimental analysis of behavior, 1966 · doi:10.1901/jeab.1966.9-521