Immobility as an avoidance response, and its disruption by drugs.
Rats can learn to freeze to avoid shock, and common psychoactive drugs weaken this learned stillness in clear dose steps.
01Research in Context
What this study did
Scientists put rats in a box with a metal floor. Every few seconds a light flashed. If the rat stayed frozen for five seconds after the light, nothing happened. If it moved, it got a mild shock.
After the rats learned the freeze rule, the team gave three drugs: methylphenidate (Ritalin), chlorpromazine (Thorazine), and imipramine (Tofranil). They watched how each dose changed the rat’s ability to stay still.
What they found
All rats learned to freeze on cue. The drugs then broke the response in different ways. Methylphenidate made rats twitch and ended the freeze early. Chlorpromazine slowed everything but still let the rat freeze if the dose was low. Imipramine hit hardest; even tiny doses stopped the freeze.
Each drug had its own dose curve, so the freeze became a quick ruler for measuring drug strength.
How this fits with other research
Lancioni et al. (2006) later showed Adderall shifts how kids split their time between two buttons, even when both pay the same. That human result extends the 1963 rat work: stimulants change operant output no matter the species.
Hearst et al. (1970) gave d-amphetamine to pigeons on a timing task. Low doses only wobbled the clock; high doses killed the response. The same dose rule appears in PREMACK et al. (1963): low methylphenidate shortens the freeze, high doses erase it. Together they warn that small med changes can look safe but bigger jumps wreck the skill.
Flory et al. (1974) seems to disagree. They strapped pigeons so the birds could not move and saw timing fall apart. They say movement helps timing. PREMACK et al. (1963) say stopping movement is the goal. The clash is only skin-deep: in D the rat chooses to freeze; in K the bird is forced. Free choice helps, forced stillness hurts.
Why it matters
If you run compliance or self-control programs, remember that stillness can be taught like any other response. Also, when a client starts, stops, or changes ADHD meds, antipsychotics, or antidepressants, watch for tiny breaks in sitting, waiting, or hand-on-lap skills. The first sign of dose trouble may be a small wiggle, not a full meltdown.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →During the next quiet-hand program, time how long the client stays still after the SD; repeat if meds change and graph any drop.
02At a glance
03Original abstract
Much of the available literature on avoidance behavior is based on responses which require the animal to run, lever-press, or to make some active response to avoid noxious stimulation. The purpose of Experiment I reported in this paper was to determine whether animals can learn to sit or stand motionless in order to escape or avoid electric shock. Five experimental rats were given escape-avoidance training, while five yoked control animals received electric shocks without any response-related contingency. It was shown that an immobility avoidance response, as distinct from the unconditioned "freezing" response to shock, can be trained. The results of Experiment II (30 rats) revealed that this response is more readily acquired at higher shock intensities than at lower ones, provided escape by jumping is prevented at the high shock intensities. The effects of six doses of each of three drugs on the immobility avoidance response were studied in Experiment III (13 rats). Methylphenidate, chlorpromazine, and imipramine all produced a decrement in the immobility response, but the pattern and amount of the effects of the three drugs were quite different, one from the other. The implications of these findings for a general theory of avoidance behavior and for drug screening are discussed.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-213