Chapter Ten – Aversive Control: Avoidance and Punishment
Avoidance procedure: the individual has to make a specific response to prevent an aversive stimulus from
occurring. Involves a negative contingency between an instrumental response and the aversive stimulus. If the
response occurs, the aversive stimulus is omitted. Putting your hand on a railing to avoid slipping. Sometimes
referred to as active avoidance
Punishment: involves a positive contingency: the target response produces the aversive outcome. If you touch a hot
stove, you will get burned! Sometimes referred to as passive avoidance
-Avoidance procedures increase the occurrence of instrumental behaviour, whereas punishment procedures
suppress instrumental responding.
Origins of the Study of Avoidance Behaviour
-Originated in the studies of classical conditioning
-First conducted by Vladimir Bechterev: interested in studying associative learning in human subjects
-Participants placed hand on metal plate, tone went off then shock, caused participant to decide whether
they were exposed to US (shock)
The Discriminated Avoidance Procedure
-Investigators have been concerned with the importance of the warning signal in avoidance procedures and the
relation of such warning signals to the US and the instrumental response.
Discriminated, or signaled avoidance: Involves discrete trials, each trial is initiated by the warning stimulus
(CS). The events after that depend on what the subject does.
-If the subject makes the target response before the shock is delivered, the CS is turned off and the US is
omitted in that trial. This is a successful avoidance trial
-If the fails to make the required response during the CS-US interval, the shock appears and the CS and US
remain on until the required response is done. This is called an Escape Trial.
-Discriminated avoidance procedures are usually done in a shuttle box, called shuttle avoidance. There are two
1. Two-way shuttle avoidance: when the animal moves from one side of the shuttle box to the other on
2. One-Way shuttle avoidance: when the animal starts each trial on one specific side, and moves away from
the US to same direction every time. It is easier to learn than two-way.
Two-Process Theory of Avoidance
Fundamental question in the study of avoidance: Can the absence of something provide reinforcement for
-Two mechanisms are involved in avoidance learning:
1. Classical conditioning of fear to the CS: Classical conditioning process activated by pairings of the warning
stimulus (CS) with the aversive event (US) on trials when the organism fails to make the avoidance
2. Instrumental reinforcement of the avoidance response through fear reduction: learning that the instrumental
avoidance response occurs because the response terminated the CS thereby reduces the conditioned fear
elicited by the CS.
-It explains avoidance behaviour in terms of escape from conditioned fear rather than in terms of prevention of
Experimental Analysis of Avoidance Behaviour Acquired-Drive Experiments
-Attempting to demonstrate the classical conditioning of fear and the instrumental reinforcement through fear
reduction in a situation where these two types of conditioning are not intermixed and make separate contributions
to avoidance learning.
-First condition fear to a CS in a classical conditioning procedure.
-Second subjects are periodically exposed to the dear-eliciting CS, and allowed to make instrumental
responses to turn off the CS
-More recently this procedure has been referred to as the Escape form fear (FFE) paradigm
Independent Measurement of Fear During Acquisition
-This approach is based on the assumption that if fear motivates and reinforces avoidance responding, then the
conditioning of fear and the conditioning of instrumental avoidance behaviour should go hand in hand.
-Contrary to this prediction, however, conditioned fear and avoidance responding are not always highly
correlated. E.g. Dogs become less fearful as they become proficient in performing avoidance responding, because
they are aware that they can stop the aversive stimulus.
-Successful avoidance behaviour is associated with low levels of fear and low expectations of danger
Extinction of Avoidance Behaviour Through Response-Blocking and CS-Alone Exposure
-Since avoidance responses can become persistent how might avoidance behaviour be extinguished?
Flooding or response prevention: Presenting the CS in the avoidance situation without the US, but with the
apparatus altered in such a way that the participant is prevented from making the avoidance response.
-Flooding responses have two important components:
1. Being exposed to the CS without the aversive stimulus: blocked exposure to the CS facilitates
extinction of the avoidance response. The effect is determined by the total duration of exposure to
2. Blocking access to the avoidance response also facilitates extinction.
Non-Discriminated (Free-Operant) Avoidance
-Can subjects still learn an avoidance response if there is no external warning stimulus in the situation?
-Sidman devised an avoidance conditioning procedure that did not involve a warning stimulus called non-
discriminated, or free-operant avoidance.
- The aversive stimulus (shock) is scheduled to occur periodically without warning. E.g. every five seconds. Each
time the subject makes an avoidance response it gets a period of safety. E.g. 15 seconds. Repetition of the
avoidance response before the safe period is over, starts the safe period over again.
-Constructed from two time intervals:
1. The intervals between shocks in the absence of a response. Called the S-S clock (shock-shock) interval. In
the example it was 5 seconds
2. The interval between the avoidance response and the next scheduled shock. Called the R-S clock
(Response-shock) interval. In the example it was 15 seconds
Free-Operant Avoidance and Two-Process Theory
-Free-Operant Avoidance behaviour presents a challenge for two-process theory because there is no explicit CS,
but the maintain that because the S-S and R-S intervals are rather short, the passage of time can be responded to
and used as a signal for shock.
Alternative theoretical Accounts of Avoidance Behaviour
Positive Reinforcement Through Conditioned Inhibition of Fear or Conditioned Safety Signals