Aversive Control and Avoidance Behaviors

Throughout history, man has relied on aversive acts to control the behavior of other men. This control, in general, took the form, "If you do X, you will get punished," as well as the form, "If you do not do Y. something bad will happen to you." What is known about aversive control? Is it effective in the long run? In this module you will find answers to these questions.

As you read the text, keep the following questions in mind. What is negative reinforcement?

How does it differ from punishment?

How are escape and avoidance behaviors conditioned in the laboratory?


Life, as they say, is not a bow] of positive reinforcers. Everybody experiences in his lifetime events which are extremely annoyingÄor worse. What do psychologists know about such events? First, their name: aversive events. Aversive stimuli are those stimuli which an animal will work to avoid or terminate. In other words, aversive stimuli are those whose removal or termination can be shown to be reinforcing.


Recall that a reinforcing event is one that increases the frequency of the behavior it closely follows. For example, a baby cries (responds) and receives a bottle (positive reinforcement). The baby's crying behavior is thus strengthened (is more resistant to extinction). But the same situation from the viewpoint of the mother looks quite different; she finds the baby's crying aversive and she would like to terminate it. When she makes the response of feeding the baby, the aversive stimulation of his crying is terminated and her behavior is thus reinforced. This is illustrated below.


Wakes up hungry ---- Cries Receives bottle--- (response) (positive reinforcement for baby)


Hears crying (aversive stimulus) ---- Gives bottle (response) -- Crying stops (negative reinforcement for mother)

Example of a positive and negative reinforcement in a mother-infant interaction

It is important to note that the behaviors being emitted by both the mother and the child are being increased in strength. Reinforcement, either positive or negative, always strengthens behavior. It is erroneous to think of the effects of aversive stimulation only in terms of punishment. Punishment is used in trying to eliminate or suppress a behavior, not to reinforce it. Remember: Positive reinforcement--An event that increases the probability of response when its occurrence is contingent upon the emission of that response. Negative reinforcement -- An event that increases the probability of response when its termination is contingent upon the emission of that response.

It is important not to confuse negative reinforcement with punishment. In negative reinforcement the organism's response terminates a noxious stimulus and the response is strengthened. In punishment, the organism's response initiates a noxious stimulus and the response is less likely to occur again, at least for a while.

One reason we do not touch hot stoves is that earlier grasping of hot objects has brought pain -- the pain was punishment. When we hear a knocking in a car engine, we respond by taking the car to a mechanic in order to eliminate the ominous sound. If the mechanic was good, the sound is gone, and its removal constitutes negative reinforcement.

In punishment, the aversive stimulus always follows the response in question; in negative reinforcement, the aversive stimulus always precedes the response in question, and the response removes the aversive stimulus. The comparison is shown below.

Punishment Response -----> aversive stimulus

Negative Reinforcement -----------> Aversive stimulus --------->response withdrawal of aversive stimulus


The kind of learning that results from negative reinforcement is escape learning. An animal escapes shock by pressing a bar. The mother is escaping from the aversiveness of the baby's crying by feeding him. Most mothers, however, soon learn that they can avoid the baby's crying altogether if they learn to read the baby's signals. When the baby wakes up, he usually grunts and fusses before crying. A mother soon learns that she can avoid crying if she feeds the child immediately. The fussing noise is called a conditioned aversive stimulus. It is the antecedent event that signals that the aversive event is about to occur.

A tone, a distinctive light, a buzzer, or any stimulus that precedes a shock will quickly become a conditioned aversive stimulus. The experimenter can arrange matters so that the stimulus appears a few seconds before the shock. When the rat presses the bar, he terminates the signal and avoids the shock altogether. This procedure is called avoidance conditioning. The difference between escape and avoidance conditioning is shown in Figure 11 below. As can be seen, avoidance learning results from escape learning. The only difference is that the organism makes the response before the primary aversive stimulus occurs, and thus avoids it.

In one sense, there is no difference between avoidance and escape conditioning. The response in both cases terminates an aversive stimulus. Behaviors reinforced in both avoidance and escape conditioning are strengthened and become more difficult to extinguish. Another property of behavior generated and maintained by aversive control is worth noting. The behavior tends to become stereotyped or inflexible. In escape conditioning, for example, the rat will typically crouch by the bar, ready to press it as soon as the shock is administered. He does not move about in the environment as much as he would if positive reinforcement were being used to condition bar-pressing.

ESCAPE CONDITIONING Shock goes Off ------ when response is made

AVOIDANCE CONDITIONING If response is made when the signal tone comes on, then the shock never occurs.

Many human behaviors are maintained by a "Doomsday Contingency"


As the introduction to this module pointed out, aversive control has been used widely throughout history. In particular, harsh forms of government such as dictatorships specialize in aversive control. Military organizations, even within democracies, achieve control by a sort of standing threat that all disobedience will be punished. Although people may tolerate such aversive control for a while, they usually are not happy in that kind of situation. They will react against it or leave it whenever possible. Acts of sabotage and deliberate under-achievement also plague systems that rely heavily on threat and punishment.

Thus, from a humanitarian standpoint, we would be reluctant to employ aversive control. From a practical standpoint, we note that such control may not be effective over long periods as people will seek to sabotage, overthrow, or in other ways escape from aversive systems of control.


Everybody knows the old story, or some variation of it, in which two people are walking down the street. One of them constantly snaps his fingers. His companion turns to him to ask, "Why do you keep snapping your fingers all the time?" His companion answers, "I'm keeping away the tigers!" The other says, "But there aren't any tigers for thousands of miles." His finger- snapping companion answers, ''See, it's working."

All avoidance behaviors, including such superstitions, are difficult to get rid of (Numberger, Ferster,and Brady, 1963). The reason is that the signal preceding an aversive stimulus becomes itself a conditioned aversive stimulus, and the organism seeks to escape from it. In real life there are a great many ways to escape conditioned aversive stimuli, and any successful escape is always negatively reinforced, following the usual principles of escape conditioning. For example, if a black cat is seen as an "evil omen," a person may cross the street, or even turn back home to escape the stimulus. Each successful escape reinforces the tendency to flee from black cats.

Tics, phobias, compulsions and other neurotic symptoms typically are escapes from conditioned aversive stimuli that once preceded primary aversive stimuli. The fact that the primary aversive stimuli may be completely eliminated does nothing to weaken the escape behavior related to the signals that once preceded them.



Now test yourself without looking back.
1. What is escape behavior?

2. What is avoidance behavior?

3. In negative reinforcement, the aversive stimulus appears:
a. before the response.
b. after the response.
c. with the reinforcement.
d. after the reinforcement.

4. In punishment, the aversive stimulus appears:
a. before the response.
b. after the response.
c. before the reinforcement.
d. after the reinforcement.

5. The response in both avoidance and escape conditioning terminates a(n)

6. What type of control seems to be preferable with humans?


Now, be sure to do the exercises that follow



Aversive stimuli are those that an animal will work to terminate.A rat is conditioned to press a bar when he hears a tone and this Which of the following might normally be aversive stimuli to a rat?prevents an electric shock. This is not escape conditioning because:

a. A painfully loud noise
b. A food pellet
c. Sugar water
d. An electric shock

________________________________________________________ 5

A rat is conditioned to press a bar to turn off an electric shock
when he feels it. By pressing the bar, the rat:

a. escapes from the shock.
b. causes the aversive stimulus to be withdrawn.
c. can prevent the shock.
d. can avoid the shock completely.

___________________________________________________ 8

In escape conditioning, the animal terminates an aversive stimulus. He therefore receives negative reinforcement. Negative reinforcement is:

a. the same as punishment.
b. the withdrawal of positive reinforcers
c. the termination of an aversive stimulus..

_____________________________________________________ 3

A rat undergoes conditioning and is taught to pull a string to terminate an electric shock.
a. The shock is the____________________________________
b. The conditioned response is_____________________________
c. The type of conditioning is____________________________________

__________________________________________________________ 2

a. no aversive stimulus is present.
b. the rat does not terminate the shock, but avoids it.
c. the rat is punished if he presses the bar.
d. positive reinforcement is used. ____________________________________________________________________ 7

In avoidance conditioning, a subject responds to a "warning signal', or "conditioned aversive stimulus" and thus:
a. receives positive reinforcement.
b. avoids an aversive stimulus.
c. (neither) _________________________________________________________________6

A rat is conditioned to press a bar whenever a light comes on, and by so doing he prevents an electric shock.

a. The conditioned aversive stimulus is______________________________

b. The basic aversive stimulus is________________________________________

c. The type of conditioning is____________________________________________ ___________________________________________________________________________________4

In avoidance conditioning, the animal responds to a(n)__________________________________________

to avoid a(n)________________________________________________________ _______________________________________________________________________ 1


1 conditioned aversive stimulus; basic or primary aversive stimulus.

a. aversive stimulus
b. pulling the string
c. escape

3 c

4 a. the light
b. electric shock
c. avoidance

5 a,d

6 b

7 b

8 a,b

Some sort of aversive stimulus is terminated in: a. escape conditioning b. avoidance conditioning. c. classical conditioning. d. positive reinforcement. ________________________________________________________________3

Positively reinforced people are generally happier and more productive than those who have been taught with aversive control. For this reason many psychologists do not recommend conditioning humans
and______________________________________________________ techniques. ___________________________________________________________________2

Behaviors conditioned by aversive control are generally more difficult to extinguish than those conditioned by positive control. Which of the following bar-pressing behaviors would be least difficult to extinguish?

a. A rat presses a bar to turn off an electric shock.
b. A rat presses a bar to turn off a buzzer and prevent an electric shock.
c. A rat presses a bar to receive a food pellet.


1 c
2 escape avoidance
3 a b
4 aversive control




1. What is a negative reinforcement?

2. A rat terminates an electric shock by pressing a bar. This is an instance of

3. A rat sees a light flash and immediately presses a bar so that he won't receive a shock four seconds later. This is an instance of

4. Punishment is used in:
a. escape conditioning.
b. avoidance conditioning.
c. positive conditioning of operant behavior.
d. (none of these)

5. When a father says to his child, ``If you don't an A in arithmetic, I'll take your bicycle away," he is using
a. aversive control.
b. an escape technique.
c. an avoidance technique.
d. positive control.

6. Escape and avoidance-conditioned behaviors are(easy/difficult) to extinguish.


July 29, 2002