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Chapter 6

PSYC 2210 Chapter Notes - Chapter 6: Matching Law, Slot Machine, Self-Control


Department
Psychology
Course Code
PSYC 2210
Professor
Anthony Nield
Chapter
6

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Chapter 6: Choice Behaviour
Concurrent schedules involve the presence of two choices readily available and the subject
can switch from one response key to another. Concurrent schedules allow for the continuse
measurement of choice because the organism is free to change back and forth at any given time.
For example; playing the slot machine or talking with friends.
> Measures of Choice Behaviour
- The individuals choice in concurrent schedule is reflected in the distribution of its behaviour in
the two responses. One common technique to measure the responses is to calculate the relative
rate of responding on each response key. The formula looks like BL / (BL + BR). If the
distribution of pecking is the same as for both right and left, it will equal 0.5. However if the left
is greater than the right (assuming we are measuring L on the numerator), then it will be greater
than 0.5. If the Left key has less response pecks, then the result will be less than 0.5.
- We can also calculate the relative rate of reinforcement since the distribution of the subjects
response can be due to this. Note, if both response keys ive a concurrent schedule of VI 60 we
can assume the subject will respond equally to both since there is no advantage in pressing one
more than the other. We calculate the relative rate of reinforcement by rL / (rL + rR). As mentioned
earlier, if the reinforcement is equal (VI 60 and VI 60) than the relative rate of reinforcement will
equal 0.5.
> The Matching Law
- We have shown above that if the concurrent schedules are the same, relative rate of responding
(or behaviour ‘B’) is equal to the relative rate of reinforcement. But then Heinstein aked an
important question: Will it still be equal if the response alternatives were not equal? Consider for
example a concurrent BI six minute and a VI two minute schedule. VI six minute has a
maximum of six reinforcers per house and VI two minute has a maximum of 30 reinforcers per
hour. Heinstein did the experiment with no constraints, they could split their pecks or respond to
only one. As it turned out, the pigeons distributed their responses in a predictable fashion. The
results found that the relative rate of responding was always nearly very equal to the relative rate
of reinforcement earned on that alternative. If one side had more reinforcements, they pecked
that side more. The relative rate of responding on an alternative matched the relative rate of
reinforcement on that alternative. These results encouraged Heinstein to state the relation as a
law of behaviour, the matching law. There are two common mathematical expressions of the
matching law.
(1) The rate of responding or behaviour (B) and rate of reinforcement (r) on one choice
alternative are expressed as a proportion of total response and reinforcement rates:
(2) The second formula of the matching law is simpler but mathematically equivalent to
the first equation. In the second version, the rates of responding and reinforcement on one
alternative are expressed as a proportion of the rates of responding on the other alternative:
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- Both expressions of the matching law represent the same basic principle: The relative rates of
responding match relative rates of reinforcement. The matching law gave the major insight that
the rate of a particular response does not depend on the rate of reinforcement of that response
alone. Behaviour frequency does depends not only on its own schedule of reinforcement but also
on the rate of reinforcement of other activities the individual may perform. For example, when
trying to motivate a student to study we must take into consideration all the other reinforcers that
they have at their disposal. Based on the concepts of the matching law, Bulow and Meller
predicted that adolescent girls who live in reinforcement lacking environments are more likely to
engage in sexual behaviour as opposed to those whose environments are full of reinforcement
activities. Bulow and Meller put the results in the matching law formulas and found that
matching law predicted the frequency of sexual activity with accuracy of 60% and predicted
contraceptive use with 67% accuracy. These findings suggest that to reduce unprotected sex
among teenagers, one must not only consider sexual activities but other things they may learn to
enjoy (ex. sports).
> Mechanisms of The Matching Law
- Matching law describes how organisms distribute their responses in a chance situation, but does
not explain what mechanisms are responsible for this response distribution It is a descriptive law
of nature instead of a mechanistic law. The matching law is stated in terms of rates of responding
and reinforcement averaged over the entire duration of experimental sessions. It ignores when
individual responses are made. Some theories of matching are similar in that they ignore the
level of individual responses. Such explanations are called molar theories. Molar theories explain
aggregate of responses. They deal with the overall distribution of responses and reinforcers in
choice situations. In contrast to molar theories, other explanations of the matching relation focus
on what happens at the level of individual responses and view the matching relation as the net
result of these individual choices. Such explanations are called molecular theories.
> Matching and Maximizing rates of reinforcement
The most extensively investigated explanations of choice behaviour are based on the intuitively
reasonable idea that organisms distribute their actions among response alternatives so as to
receive the maximum amount of reinforcement possible in the situation. According to this idea,
animals switch back and forth between response alternatives so as to receive as many reinforcers
as they possible can. The idea that organisms maximize reinforcement has been used to explain
choice behaviour at both molecular and molar levels of analysis.
> Molecular Maximizing:
- According to molecular theories of maximizing, organisms always choose whichever response
alternative is most likely to be reinforced at the time. Shimp proposed an early version of
molecular matching. He suggested that when two schedules ( and B) are in effect simultaneously,
the subject switches from schedule A to schedule B as the probability of reinforcement for
schedule B increases. Shimp proposed that the matching relation is a byproduct of prudent
switching when the probability of reinforcement on the alternative response key becomes greater
than the probability of reinforcement on the current response key.
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