The stay/switch model describes choice among magnitudes of reinforcers.

Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States.
Behavioural Processes (Impact Factor: 1.46). 07/2008; 78(2):173-84. DOI: 10.1016/j.beproc.2008.03.002
Source: PubMed

ABSTRACT The stay/switch model is an alternative to the generalized matching law for describing choice in concurrent procedures. The purpose of the present experiment was to extend this model to choice among magnitudes of reinforcers. Rats were exposed to conditions in which the magnitude of reinforcers (number of food pellets) varied for staying at alternative 1, switching from alternative 1, staying at alternative 2 and switching from alternative 2. A changeover delay was not used. The results showed that the stay/switch model provided a good account of the data overall, and deviations from fits of the generalized matching law to response allocation data were in the direction predicted by the stay/switch model. In addition, comparisons among specific conditions suggested that varying the ratio of obtained reinforcers, as in the generalized matching law, was not necessary to change the response and time allocations. Other comparisons suggested that varying the ratio of obtained reinforcers was not sufficient to change response allocation. Taken together these results provide additional support for the stay/switch model of concurrent choice.

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Available from: Jim Macdonall, Oct 16, 2014
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    • "Even in these situations, a variety of animals choose larger amounts of foods when given choices between discrete sets of identical food items (e.g., Addessi, Crescimbene, & Visalberghi, 2008; Anderson, Awazu, & Fujita, 2000; Anderson et al., 2005; Beran, 2001; Call, 2000; Hanus & Call, 2007; Rumbaugh, Savage-Rumbaugh, & Hegel, 1987; Uller, Jaeger, Guidry, & Martin, 2003) and continuous quantities such as liquids (e.g., Suda & Call, 2005; vanMarle, Aw, McCrink, & Santos, 2006; Wood, Hauser, Glynn, & Barner, 2008). Extensive research has shown that magnitude of food reward guides choice behavior in a variety of contexts even when other variables such as delay length to reward and unpredictability of reward also are manipulated (e.g., Green, Myerson, Holt, Slevin, & Estle, 2004; Landon, Davidson, & Elliffe, 2003; MacDonall, 2008; Steinhauer, 1984; Young, 1981). "
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    ABSTRACT: The authors investigated choice behavior by chimpanzees in five experiments involving choices between different amounts of food. Chimpanzees did not maximize the amount of food they obtained when choosing between a single 20-g banana piece and another option containing a 20-g piece and a 5-g piece. This was true even though they successfully discriminated between 20-g and 25-g banana pieces in other trials. When items in the mixed option were stacked, however, the chimpanzees chose the larger amount. Later experiments indicated that changing the magnitude of the two amounts did not change performance if the difference in magnitude between the two options remained the same (e.g., 40 g plus 10 g vs. 40 g). However, chimpanzees did improve when the two-item option was increased in its magnitude relative to the single slice (e.g., 20 g plus 10 g vs. 20 g). These results indicated that chimpanzees undervalued the total amount of food in sets when items differed in size and did not appear to be whole. Another experiment confirmed that it was this notion of wholeness that evoked suboptimal responding because chimpanzees were successful in the same comparisons with a different type of food that appeared less fractionated when presented as two pieces. These results provide evidence of suboptimal responding in some natural choice situations that prevents chimpanzees from maximizing food intake.
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