Effects on responding of mixed and multiple schedules of signalled and unsignalled response-dependent electric-shock delivery.
A warning stimulus softens punishment only when the schedule lets the stimulus become a real cue.
01Research in Context
What this study did
The team set up two kinds of schedule. In one, a light always came on before shock. In the other, shock arrived with no warning. They ran both versions inside mixed and multiple schedules to see which setup hurt responding less.
Animals pressed a lever for food. Shock followed some presses. The key question: does the warning light help only when the schedule lets the light become a clear cue?
What they found
Signalled shock did less damage to response rates than unsignalled shock, but only under the multiple schedule. In the mixed schedule, the light made no difference. The schedule structure, not the signal alone, decided how much behavior dropped.
The result shows that a warning helps only when the learner can tell which part of the schedule they are in.
How this fits with other research
Macdonald et al. (1973) already showed that a signal cuts suppression. The new twist: the schedule must let the signal act as a true discriminative stimulus. The earlier paper did not test mixed versus multiple, so Hymowitz (1976) extends that work by pinning the effect on schedule architecture.
Davis et al. (1976) worked in the same lab the same year. They asked whether the signal comes before or after shock. Hymowitz (1976) adds where the signal sits inside the whole schedule. Together they map both time and context.
Wilkie (1973) found that signalled reinforcement creates contrast in multiple schedules. Hymowitz (1976) shows the same schedule type also lets a warning stimulus shield against punishment. The two papers sit on opposite sides of the coin: one with rewards, one with aversives, both pointing to the power of multiple schedules to give stimuli control.
Why it matters
If you use punishment or negative reinforcement, pair the aversive event with a clear stimulus and run it inside a multiple schedule. The learner then knows exactly when the rule is on and when it is safe to respond. Without that schedule frame, the signal is just noise and behavior keeps falling.
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02At a glance
03Original abstract
Responding in two rats was maintained under mixed and multiple variable-interval 35-sec variable-interval 35-sec food delivery schedules. Similar rates and patterns of responding occurred in each component of the two schedules. Mixed and multiple variable-interval 65-sec variable-interval 65-sec schedules of response-dependent shock delivery were super-imposed on the mixed and multiple baseline food schedules, respectively. In one component, a 5-sec stimulus was presented on the average of once every 65 sec. Offset of the stimulus arranged that the next response would produce shock. In the other component, no stimulus was presented during the 5-sec period. The mixed schedule of signalled and unsignalled dependent shock delivery yielded similar degrees of response suppression in each component, but the multiple schedule of shock delivery revealed differential degrees of response suppression. Considerably more suppression occurred in the component not associated with the preshock stimulus, thus implicating the discriminative functions of the correlated stimulus.
Journal of the experimental analysis of behavior, 1976 · doi:10.1901/jeab.1976.25-321