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B. F. Skinner
Radial Behaviorism
B.F. Skinner
(1904-1990)
•1925: Hamilton College
(NY): degree in English,
no courses in psychology
•Read about Pavlov’s
and Watson’s
experimental work
•1931: Ph.D. from
Harvard
What did Skinner study?
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Findings about the ways animals discover and learn things
Most actions (or behaviours) are basically learned, and
can be unlearned and changed.
“Personality is the result of measuring outside forces.
Thus, how we think and act can be modified by
manipulating our environment.” (ABC’s of the Human
Mind)
B. Operant Conditioning

Learning occurs through the presentation of
rewards or punishments that influence
voluntary behaviors.
Operant Conditioning

Changes in behavior is the outcome of an
individual responding to occurrences in the
environment (stimuli)

If the subject is correctly stimulated it will give the
suitable response

When a stimulus-response pattern is reinforced
(rewarded), the individual is conditioned to respond
in a certain manner
Operant Conditioning – BF
Skinner
Law of effect (Thorndike) = if a behavior
is followed by a better or more satisfying
state of affairs, that behavior is more
likely to occur again in the future. If a
behavior is followed by a less satisfying
state of affairs, that behavior is less
likely to occur in the future.
Operating Conditioning Concepts
Neutral operants:

responses from the environment that neither increase
nor decrease the probability of a behavior being
repeated.
Reinforcer – anything that strengths a behavioral tendency
 Positive reinforcement = getting something good
 Negative reinforcement = taking away something
aversive
Punishment – anything that weakens a behavioral tendency
 Can remove something positive (from positive to
neutral)
 Can give something negative (go from neutral to
negative)
Skinner’s Work:

Skinner showed that by presenting animals (tested on pigeons
and rats) or people with rewards & punishments you could
shape behavior.
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Initially, to get a new behavior to appear & then be
conditioned, you have to use shaping.

Shaping involves presenting a reinforcement for each
successive approximation of a desired behavior.

E.g., if we want to shape lever pressing in rats, we would reinforce
any behavior that even remotely resembles lever pressing.
Reinforcement-strengthens a behavior

1. Positive Reinforcement: Strengthens a
response by presenting something that is perceived
as appetitive (pleasant) after a behavior is emitted.
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E.g., a good grade received after
studying for an exam, a food reward
for pressing a lever, etc.
2. Negative Reinforcement: strengthens a
response by removing an aversive(negative)
stimulus after a behavior is emitted.

E.g., people smoke more, to reduce
aversive sensations associated with
nicotine withdrawal.
Punishment: Two forms

1. Positive Punishment - apply an aversive stimulus
when an undesired behavior occurs. Must be
immediate to be effective.

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E.g., presenting lemon juice on a toddler’s
tongue immediately after he or she bites.
2. Negative Punishment - remove an appetitive
(pleasant) stimulus when an undesired behavior
occurs.
E.g., revoking a teenager’s driving
privileges if they get a speeding ticket.
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Skinner Box

Skinner created an apparatus that would
present rewards to an organism (animals &
humans!!) based on their behavioral
responses.
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He even had his daughter stay in the box for
several experiments.
Lab Experiment:
Skinner’s Box and Rats
Skinner’s Rats
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Rats were placed in metal cages with
a number of levers.
The rats first accidentally pressed the
levers in the cage, causing food or
water to drop into a dish.
After repeating the action, the
rats saw that they could receive food
and water by pressing the lever.
(Learned this behaviour)
So, when the rats were rewarded they
were conditioned to repeat this
positive action to continue being
rewarded
Reinforcement

Continuous Reinforcement: Every time the rat does the
appropriate behavior, he gets a pellet (food).

Fixed ratio schedule: If the rat presses the pedal three times,
he gets a pellet…or five times, or twenty times, or x times.
There is a fixed ratio between behaviors and reinforcers.

Fixed interval schedule: If the rat presses the bar at least
once during a particular period of time, say 20 seconds, he gets
a pellet. But whether he presses the bar once or a hundred
times within that 20 seconds, he only receives one reinforcer.

Variable ratio schedule: You change the x each time. First it
takes 3 presses to get a pellet, then 10, then 4, etc.

Variable interval schedule: You keep changing the time
period. First 10 seconds, then 35, then 5, then 40.
Skinner’s Box and Rats

http://www.youtube
.com/watch?v=PQtD
TdDr8vs
What if the rat doesn’t get any
more pellets?
EXTINCTION:
After a few futile attempts, the rat stops
the bar-pressing behaviour
Skinner Box &
Pigeons
Skinner conditioned the pigeon’s to
peck at a particular colored disk only
when a light was on the cage and
thus, getting rewarded by food and
water.
This is based on Skinner’s theory of
Operant Conditioning- behaviours
are repeated if they are rewarded,
and behaviours that are punished
will be avoided
Light=Primary Reinforcer
Food &Water: Secondary Reinforcer
VIDEO
Importance of Skinner:
Behaviour Modification
Definition:
adjusting the environment to change
behavior by the use of timely
reinforcement (positive and negative)
Behaviour Modification &
Skinner
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Believed that people could be
persuaded to show “good” behaviour if
they were properly reinforced for
displaying them
If they displayed bad behaviour, the
reward would be withheld.
Behaviour Modification and
The Big Bang Theory
Video
Why is it important to the
social sciences?

Knowing how people learn behaviour is a necessity
to our society so that we can control and promote the
good behaviour, which will benefit society as a whole.
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The theory of operant-conditioning helps us to control
the way humans learn behaviour and how society
can be a great influence on behaviour
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Helps us to understand how to improve behaviours
(people with problem behaviours and criminal
histories)