Chapter 4 – Reinforcement
Reinforcement: the process in which a behaviour is strengthened by the immediate
consequence that reliably follows its occurrence.
When a behaviour is strengthened, it is more likely to occur in the future.
Getting the food was the consequence that reinforced (strengthened) the cat’s
behaviour of hitting the lever to get out of the box.
When a behaviour results in a favourable outcome (contributes to well-being/survival of
the animal), that behaviour is more likely to be repeated in the future in similar
Reinforcement may occur naturally, as a result from interactions with social/physical
environment, or it may be planned as a part of a BMod program.
Reinforcement is defined as:
1. The occurrence of particular behaviour
2. Is followed by an immediate consequence
3. That results in the strengthening of the behaviour.
A behaviour that is strengthened through the process of reinforcement is called an
operant behaviour. The consequence that strengthens an operant behaviour is called a
Child cries at night when she is put to bed. The crying = operant behaviour. The
reinforcer was the attention that she got from her parents. The crying resulted in
the immediate consequence (reinforcer) the child’s crying was strengthened.
You reinforce a behaviour, not a person.
Positive and Negative Reinforcement
Both positive and negative reinforcement both strengthen behaviour.
Positive reinforcement: 1. The occurrence of a behaviour
2. Is followed by the addition of a stimulus (a reinforcer) or an increase in the
intensity of a stimulus,
3. Which results in the strengthening of the behaviour
1. The occurrence of a behaviour
2. Is followed by the removal of a stimulus (an aversive stimulus) or a decrease in
the intensity of a stimulus,
3. Which results in the strengthening of a behaviour
Stimulus: an object or event that can be detected by one of the senses and has the
potential to influence the person.
Positive reinforcer: the stimulus that is presented or that appears after the behaviour (in
Aversive stimulus: Stimulus that is removed or avoided after the behaviour (in negative
The difference between the two reinforcements, in positive reinforcement a reponse
produces a stimulus (positive reinforcer). In negative reinforcement, a response
removes or prevents the occurrence of a stimulus (aversive stimulus).
Negative reinforcement and punishment are not the same. Negative
reinforcement strengthens or increases a behaviour. Punishment decreases or
weakens a behaviour.
When you have to anayze a situation and determine whether it illustrates positive or
1. What is the behaviour?
2. What happened immediately after the behaviour? (Was a stimulus added or
3. What happened to the behaviour in the future? (Was the behaviour
strenghtened? Was it more likely to occur?)
Social vs. Automatic Reinforcement
Social Reinforcement: when a behaviour produces a reinforcing consequence through
the actions of another person.
Example: asking your friend to bring you a bag of chips. (Positive) Asking your
friend to turn down the TV. (Negative) Automatic reinforcement: when the behaviour produces a reinforcing consequence
through direct contact with the physical environment.
Example: Getting the remote and turning down the TV yourself. (Negative)
Premark Principle: A type of positive reinforcement involving the opportunity to engage
in a high-probability behaviour (preferred behaviour) as a consequence for a low-
probability behaviour (less liked behaviour), to increase the low-probability behaviour.
Having to do homework (low-probability) before going outside to play (high-
probability). The child is more likely to do their homework so they can be able to
Escape and Avoidance Behaviours
When defining negative reinforcement, a distinction is made between escape and
Escape: the occurrence of the behaviour results in the termination of an aversive
stimulus that was already present when the behaviour occurred. The person
escapes from the aversive stimulus by engaging in a particular behaviour and
that particular behaviour is strengthened.
o Example: a rat jumps over the barrier in order to exape from the shock.
The rat then learns to jump over the barrier the instant the shock in
Avoidance: the occurrence of the behaviour prevents an aversive stimulus from
occuring. The person avoids the aversive stimulus by engaging in a particular
behaviour and that behaviour is strengthened.
o Example: A tone is presented before a shock is applied. The rat learns to
jump over the behaviour at the sound of the tone, even before the shock is
Example of Avoidance/Escape Behaviours
Escape: A person steps onto hot asphalt and immediately jumps off.
Avoidance: A person puts on shoes before they step onto the hot asphalt.
Conditioned and Unconditioned Reinforcers Natural positive reinforcers like food, water, etc. because they contribute to survival of
the individual and the species. Natural negative reinforcers like escape from painful
stimulation or extreme levels of stimulation (cold, heat, etc.) because the avoidance of
these stimuli also contribute to survival.
These natural reinforcers are unconditioned reinforcers because they act as
reinforcers the first time they are presented to most humans. No previous
experience with stimuli is needed to make them reinforcers.
Conditioned reinforcers: a stimulus that was once neutral (does not currently function as
a reinforcer) but becomes establisged as a reinforcer after being paired with an
unconditioned reinforcer or an already e