Delay Discounting of Qualitatively Different Reinforcers in Rats

Calvert, Amanda L.; Green, Leonard; Myerson, Joel

doi:10.1901/jeab.2010.93-171

Cited by 53 publications

(72 citation statements)

References 24 publications

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“…Thus, food quality did not affect capuchins' temporal preferences. Our results are in agreement with previous findings obtained in rats (Calvert et al 2010), but contrast with the outcome of a series of experiments on the role of food quality and quantity on individual performance in two delay maintenance tasks (i.e. the delayed exchange task and the accumulation task) carried out in birds.…”

Section: Discussionsupporting

confidence: 92%

“…Several studies have investigated whether increasing the quality of a delayed reward decreases the rate at which it is discounted. Calvert et al (2010) used three differently preferred types of pellets and two differently preferred liquid rewards to test rats in a delay choice task with an adjusting-amount procedure. Although all rats showed clear food and liquid preferences, their discounting rate was similar across all rewards.…”

Section: Introductionmentioning

confidence: 99%

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When is it worth waiting for? Food quantity, but not food quality, affects delay tolerance in tufted capuchin monkeys

et al. 2015

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When faced with choices between smaller sooner options and larger later options (i.e. intertemporal choices), both humans and non-human animals discount future rewards. Apparently, only humans consistently show the magnitude effect, according to which larger options are discounted over time at a lower rate than smaller options. Most of the studies carried out in non-human animals led instead to negative results. Here, we tested ten tufted capuchin monkeys (Sapajus spp.) in a delay choice task to evaluate whether they show a magnitude effect when choosing between different quantities of the same food or when the options are represented by high- and low-preferred foods in different conditions. Whereas food quality did not play a role, we provided the first evidence of an effect of the reward amount on temporal preferences in a non-human primate species, a result with potential implications for the validity of comparative studies on the evolution of delay tolerance. In contrast with human results, but as shown in other animal species, capuchins' choice of the larger later option decreased as the amount of the smaller sooner option increased. Capuchins based their temporal preferences on the quantity of the smaller sooner option, rather than on that of the larger later option, probably because in the wild they virtually never have to choose between the above two options at the same time, but they more often encounter them consecutively. Thus, paying attention to the sooner option and deciding on the basis of its features may be an adaptive strategy rather than an irrational response.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

When is it worth waiting for? Food quantity, but not food quality, affects delay tolerance in tufted capuchin monkeys

et al. 2015

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“…More work will be needed to determine the extent to which these findings generalize to other drug and nondrug reinforcers, as well as to other animals. For example, rats appear to discount qualitatively different reinforcers, including both different foods and different liquids, at comparable rates, even when there are clear differences in preference between foods as well as between liquids (Calvert et al, 2010), raising the possibility that primates may differ from nonprimates in this regard.…”

Section: Discussionmentioning

confidence: 99%

“…An important finding in studies of human discounting is the relation between reinforcer magnitude and discounting rate: Humans discount larger amounts of a delayed reinforcer less steeply than smaller amounts, a finding referred to as the magnitude effect (Green, Myerson, & McFadden, 1997;Kirby, 1997;Raineri & Rachlin, 1993). In contrast, varying the magnitude of delayed reinforcers in studies with rats and pigeons, the only nonhuman species that have been rigorously tested for magnitude effects, has yet to provide evidence of a magnitude effect in animals, regardless of whether the magnitude of delayed reinforcers is varied by manipulating their amount or their quality (Calvert, Green, & Myerson, 2010;Green, Myerson, Holt, Slevin, & Estle, 2004;Richards, Mitchell, de Wit, & Seiden, 1997).…”

mentioning

confidence: 99%

“…However, other characteristics of reinforcers also may be determinants of reinforcer value in animals, and it is of interest whether such characteristics will map reliably onto utility in nonhuman animals, and perhaps especially whether they do so in nonhuman primates. Two issues are involved here: One is whether manipulating characteristics of delayed reinforcers other than their amount in such a way as to alter their value will result in a magnitude effect (Calvert et al, 2010;Farrar, Kieres, Hausknecht, de Wit, & Richards, 2003). The other is whether the subjective value of a delayed reinforcer can be assessed by manipulating the characteristics of an immediate reinforcer other than its amount until the immediate and delayed reinforcers are equally likely to be chosen (Woolverton et al, 2007).…”

mentioning

confidence: 99%

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Delay discounting in rhesus monkeys: Equivalent discounting of more and less preferred sucrose concentrations

et al. 2011

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Humans discount larger amounts of a delayed reinforcer less steeply than smaller amounts, but studies with pigeons and rats have yet to reveal such a magnitude effect, suggesting that the effect may be unique to humans. The present study examined whether the magnitude effect is observed in a species phylogenetically closer to humans, by comparing the rates at which rhesus monkeys discounted 10% and 20% concentrations of sucrose. There were no systematic differences in the rates at which the monkeys discounted the two sucrose concentrations, despite the fact that they strongly preferred the 20% concentration. Interestingly, the monkeys discounted delayed sucrose at a rate higher than was observed with delayed cocaine, and lower than was observed with delayed saccharin in previous studies (Freeman et al. Behavioural Processes, 82, 214-218, 2009; Woolverton et al. Experimental and Clinical Psychopharmacology, 15, 238-244, 2007). Taken together, these findings suggest that although both quantitative and qualitative differences can affect monkeys' preferences between immediate reinforcers, qualitative differences between types of reinforcers (e.g., sucrose vs. cocaine) can affect monkeys' discounting rates in a way that quantitative differences within a reinforcer (e.g., 10% vs. 20% sucrose) do not.

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