Effects of signaled and unsignaled shock on schedule-controlled lever pressing and schedule-induced licking: Shock intensity and body weight.
A warning signal only helps if the learner can clearly tell when relief starts.
01Research in Context
What this study did
Scientists tested how signaled and unsignaled shocks change lever pressing and licking in rats.
They varied shock strength and the rats’ body weight.
Each rat worked on a food schedule while shocks came with or without a warning tone.
What they found
Signaled shock did not always cause less suppression.
Stronger shocks stopped both lever presses and licks more than weak ones.
Lean rats stopped licking sooner than heavier rats, but lever pressing showed a mixed pattern.
How this fits with other research
Sanders et al. (1971) saw signals either help or hurt avoidance, yet shocks still went up.
Liberman et al. (1973) showed rats pick signaled shock even when it gives eight times more shocks.
Glover et al. (1976) found rats only prefer the signal when safe periods last long enough.
Together these papers say: the value of the safety gap, not the signal itself, controls behavior.
Why it matters
When you use warning stimuli, check how clear the safe period is. A short or unreliable safe window can make the signal useless or worse. Match the schedule to the client’s ability to notice the break, then watch if the target response is lever pressing, vocal, or self-care—because each type may suppress differently.
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02At a glance
03Original abstract
Schedule-controlled lever pressing and schedule-induced licking were studied in rats under a multiple fixed-interval fixed-interval schedule of food reinforcement. Following acquisition of stable rates of pressing and licking, a multiple variable-time variable-time schedule of electric-shock delivery was superimposed upon the baseline schedule. In only one component of the multiple schedule, a 5-sec stimulus preceded each shock (signaled shock). In the other component shock was unsignaled. Several shock intensities (Experiment 1) and body weights (Experiment 2) were studied. Lever pressing and licking were affected similarly by experimental manipulations, although with parametric differences. Depending upon shock intensity and body weight, rates of lever pressing and licking were hardly suppressed, suppressed primarily in the unsignaled shock component (differential suppression), or markedly suppressed in both components. Differential suppression during components with signaled and unsignaled shock and conditioned suppression of responding during the preshock stimulus appeared not to be functionally related. Differential suppression depended more on the discriminability of shock-free time, and on shock intensity, body weight, and the type of response than on the "preparatory" behavior preceding shock.
Journal of the experimental analysis of behavior, 1981 · doi:10.1901/jeab.1981.35-197