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PSYC 2210 (13)
Chapter 6

Learning Chapter 6

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York University
PSYC 2210
Anthony Nield

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 B L/ (BL + B R). 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 / (L +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: - 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 scheduleAto 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. > Molar Maximizing - Molar theories of maximizing assume that organisms distribute their responses among various alternatives so as to maximize the amount of reinforcement they earn over the long run. However, in contrast to molecular theories, molar theories focus on aggregates of behaviour over some period of time, usually the total duration of an experimental session, rather than on individual choice responses. Molar maximizing theory was originally formulated to explain choice on concurrent schedules made up of ration components.Animals don’t switch back and forth in concurrent ratio schedules, rather they respond exclusively on the ration component that requires the fewest responses. On a concurrent FR 20-FR 10 schedule, for example, the organism is likely to respond only on the FR 10 alternative. In this way, it maximizes its rate of reinforcement with the least effort. On difficulty arises from the results of concurrent VI-VI schedules of reinforcement. On a concurrent VI-VI schedule, organisms can earn close to all of the available reinforcers on both schedules, provided they occasionally sample each alternative. Another challenge for molar matching is provided by results of studies in which there is a choice between a variable ration and a variable interval schedule. Evidence does show that
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