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PIGEONS' CHOICES IN SITUATIONS OF DIMINISHING RETURNS: FIXED‐ VERSUS PROGRESSIVE‐RATIO SCHEDULES
Author(s) -
Wanchisen Barbara A.,
Tatham Thomas A.,
Hineline Philip N.
Publication year - 1988
Publication title -
journal of the experimental analysis of behavior
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.75
H-Index - 61
eISSN - 1938-3711
pISSN - 0022-5002
DOI - 10.1901/jeab.1988.50-375
Subject(s) - reset (finance) , reinforcement , statistics , schedule , mathematics , value (mathematics) , psychology , econometrics , computer science , economics , social psychology , financial economics , operating system
In two different discrete‐trial procedures, pigeons were faced with choices between fixed‐ratio and progressive‐ratio schedules. The latter schedules entail diminishing returns, a feature analogous to foraging situations in the wild. In the first condition (no reset), subjects chose between a progressive‐ratio schedule that increased in increments of 20 throughout a session and a fixed‐ratio schedule that was constant across blocks of sessions. The size of the fixed ratio was varied parametrically through an ascending and then a descending series. In the reset condition, the same fixed‐ratio values were used, but each selection (and completion) of the fixed ratio reset the progressive‐ratio schedule back to its minimal value. In the no‐reset procedure, the pigeons tended to cease selecting the progressive ratio when it equaled or slightly exceeded the fixed‐ratio value, whereas in reset, they chose the fixed ratio well in advance of that equality point. These results indicate sensitivity to molar as well as to molecular reinforcement rates, and those molar relationships are similar to predictions based on the marginal value theorem of optimal foraging theory (e.g., Charnov, 1976). However, although previous results with monkeys (Hineline & Sodetz, 1987) appeared to minimize responses per reinforcement, the present results corresponded more closely to predictions based on sums‐of‐reciprocals of distance from point of choice to each of the next four reinforcers. Results obtained by Hodos and Trumbule (1967) with chimpanzees in a similar procedure were intermediate between these two relationships. Variability of choices, as well as median choice points, differed between the reset and no‐reset conditions. Although these differences are consistent with the relative costs (in responses per reinforcement) in the two procedures, the differing dispersions of choice probably arise mainly from differing structural constraints of the two procedures.