BA410 Unit 6 Schedules and Choice Paper Example

Two Levers, Two Rates and a Dinner Table Conversation: A BA410 Unit 6 Schedules and Choice Paper

[Student Name]

Purdue University Global

BA410: Introduction to Experimental Analysis of Behavior

Unit 6 Schedules and Choice Paper

[Instructor Name]

[Date]

The writer, the lab, its animals, the family and every figure are composite and illustrative; the studies and books cited are real.

Two Levers

Choice is the subject of one of the studies running in the lab where I work as a technician. One current study, run by a doctoral student, places rats in a chamber with two levers, each on its own variable interval schedule. On the left lever, food becomes available on average every thirty seconds; on the right, on average every ninety seconds. A rat can press either lever at any time, and each lever pays off on its own schedule.

When I looked at one rat's data after several weeks, I was surprised. About three quarters of her presses were on the left lever, and about three quarters of the food she earned came from the left lever. She had not chosen one lever over the other; she had distributed her behavior in almost exactly the proportion of reinforcement each provided. The other rats in the study showed similar patterns, some more precise than others.

The Matching Law

Herrnstein (1961) reported this pattern in pigeons choosing between two keys, each on its own variable interval schedule. He found that the relative rate of pecking on each key approximately matched the relative rate of reinforcement obtained from it. If one key provided twice as much reinforcement, it received about twice as many responses. The relationship, later called the matching law, describes choice as a distribution of behavior among options rather than an all-or-none decision.

The rat in my lab fits. The left lever provided about three times as much food as the right, and she pressed it about three times as often. Ferster and Skinner (1957) had described how single schedules shape patterns of responding; Herrnstein showed how organisms allocate behavior when several schedules operate at once.

The rat was not deciding which lever was better; she was spreading her presses in proportion to what each lever paid.

Matching in People

Pierce and Epling (1983) reviewed studies of choice and matching in humans. They found that human behavior often conforms to the matching law, though with more variability than in animal studies, and that deviations from perfect matching, such as overmatching or undermatching, can be explained by factors like the cost of switching between options or differences in the quality of reinforcers.

An earlier demonstration by Conger and Killeen (1974) placed participants in group discussions in which confederates provided verbal approval, such as agreement and encouragement, at different rates. Participants directed their talk toward the confederates in proportion to the approval each provided. Social behavior, in other words, can follow the same rule as a rat's presses.

When Behavior Does Not Match

Not every rat in the study matched as neatly. One male consistently pressed the right lever more than its share of food would predict, and on some days he switched between levers so often that his presses were nearly even. The graduate student running the study explained two common deviations. Undermatching, in which preference is less extreme than the reinforcement ratio, often appears when switching between options is easy and cheap, so the animal samples both. Overmatching, a stronger preference than the ratio predicts, appears when switching is costly. In some versions of the procedure, a brief delay after each switch, called a changeover delay, is added to discourage rapid alternation, and matching usually improves.

The deviations are not failures of the law but information about what else affects choice. In everyday life, switching between options almost always has costs, such as walking to another room or changing the subject, which helps explain why human behavior matches less precisely than a rat's.

A Dinner Table

At a family dinner in November, I caught myself doing what Conger and Killeen's participants did. Two relatives sat on either side of me at the long table. My aunt asked questions, laughed at my stories and told me about her new job. My uncle answered briefly and kept checking his phone. Without planning to, I spent most of the meal turned toward my aunt. A rough count afterward, from memory, suggested I directed most of my comments to her, roughly in line with how much more responsive she was. I had not decided my uncle was less interesting, and I like him very much; my behavior had distributed itself according to the reinforcement each conversation provided.

Measuring How Much a Reinforcer Is Worth

Choice depends on reinforcer value, which raises the question of how to measure it. Hodos (1961) introduced the progressive ratio schedule for this purpose. In a progressive ratio schedule, the number of responses required for each reinforcer increases after every delivery, for example two presses, then four, then eight. Eventually the animal stops responding, and the last requirement completed, called the breakpoint, serves as a measure of how much work the reinforcer is worth.

Another study in our lab uses progressive ratios to compare two kinds of pellets, standard grain pellets and sweetened ones. Rats reach much higher breakpoints for the sweetened pellets, working through requirements several times larger before stopping. The same logic has been used in human research to measure the value of drugs, food and social rewards, and in applied settings to identify which items a child will actually work for, rather than which ones the child simply selects when offered a choice.

What the Findings Mean

The matching law suggests that changing behavior often means changing the relative reinforcement available for alternatives, not only adding or removing reinforcement for one behavior. In applied work, a child who gets more attention for disruption than for cooperation may be matching, not misbehaving out of spite. Increasing reinforcement for cooperation shifts the balance, often more effectively than trying to remove attention for disruption alone. Progressive ratios give practitioners a way to test which reinforcers are strong enough to compete.

Conclusion

A rat splitting her presses between two levers, people directing their talk toward those who approve of them and my own behavior at a family dinner all follow the matching law that Herrnstein described. Pierce and Epling's review shows its reach in human behavior, and Hodos's progressive ratio schedule offers a way to measure what reinforcers are worth. Together they explain choice as the distribution of behavior among competing sources of reinforcement.

References

Conger, R., & Killeen, P. (1974). Use of concurrent operants in small group research: A demonstration. Pacific Sociological Review, 17(4), 399-416. https://doi.org/10.2307/1388548

Ferster, C. B., & Skinner, B. F. (1957). Schedules of reinforcement. Appleton-Century-Crofts.

Herrnstein, R. J. (1961). Relative and absolute strength of response as a function of frequency of reinforcement. Journal of the Experimental Analysis of Behavior, 4(3), 267-272. https://doi.org/10.1901/jeab.1961.4-267

Hodos, W. (1961). Progressive ratio as a measure of reward strength. Science, 134(3483), 943-944. https://doi.org/10.1126/science.134.3483.943

Pierce, W. D., & Epling, W. F. (1983). Choice, matching, and human behavior: A review of the literature. The Behavior Analyst, 6(1), 57-76. https://doi.org/10.1007/BF03391874