Waiting for better, not for more: corvids respond to quality in two delay maintenance tasks

Abstract

Self-control, that is, overcoming impulsivity towards immediate gratification in favour of a greater but delayed reward, is seen as a valuable skill when making future-oriented decisions. Experimental studies in nonhuman primates revealed that individuals of some species are willing to tolerate delays of up to several minutes in order to gain food of a higher quantity or quality. Recently, birds (carrion crows, Corvus corone, common ravens, Corvus corax, Goffin cockatoos, Cacatua goffiniana) performed comparably to primates in an exchange task, contradicting previous notions that birds may lack any impulse control. However, performance differed strikingly with the currency of exchange: individuals of all three species performed better when asked to wait for a higher food quality, rather than quantity. Here, we built on this work and tested whether the apparent difference in levels of self-control expressed in quality versus quantity tasks reflects cognitive constraints or is merely due to methodological limitations. In addition to the exchange paradigm, we applied another established delay maintenance methodology: the accumulation task. In this latter task, food items accumulated to a maximum of four pieces, whereas in the exchange task, an initial item could be exchanged for a reward item after a certain time delay elapsed. In both tasks, birds (seven crows, five ravens) were asked to wait in order to optimize either the quality or the quantity of food. We found that corvids were willing to delay gratification when it led to a food reward of higher quality, but not when waiting was rewarded with a higher quantity, independent of the experimental paradigm. This study is the first to test crows and ravens with two different paradigms, the accumulation and the exchange of food, within the same experiment, allowing for fair comparisons between methods and species. (Stevens & Stephens, 2010), ranging from foraging decisions (Kacelnik, 2003; reviewed in Stephens & Anderson, 2001) to social interactions, for example mate choice (Sozou & Seymour, 2003) or reciprocity in cooperative events (Stevens & Hauser, 2004). Going for the immediately available but less preferred option instead of postponing action in favour of an overall better but delayed reward is defined as impulsivity, whereas self-control refers to the opposite strategy (Ainslie, 1974;Kalenscher, Ohmann, & Güntürkün, 2006;Logue, Chavarro, Rachlin, & Reeder, 1988). Europe PMC Funders GroupFrom an economical point of view, the preference for a maximum payoff should be selected for (Noë, Hooff, & Hammerstein, 2001) 2005). It has been commonly suggested that temporal discounting is a critical factor in intertemporal decisions (Kacelnik & Bateson, 1996;Kalenscher & Pennartz, 2008;Stevens & Stephens, 2010). Accordingly, future rewards are subjectively rated less valuable the longer the delay until they are received, because delay is associated with uncertainty for realization of the benefits and probability of loss. Alternatively, it has been argued th...

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

“…It is unlikely that the different results obtained on capuchins in the present study and on corvids and cockatoos (Auersperg et al 2013;Hillemann et al 2014;Wascher et al 2012) are due to species differences in sensitivity to quantity and quality of food rewards. In fact, also capuchin monkeys performed better in the qualitative version of a delayed exchange task than in its quantitative version (Drapier et al 2005).…”

“…the delayed exchange task and the accumulation task) carried out in birds. Corvids (Corvus corax, Corvus corone corone) and Goffin's cockatoos (Cacatua goffiniana) tested in a delayed exchange task, in which they were required to return an initial food item after a certain delay in order to obtain a higher-value reward, performed well only when they could exchange a low-quality food item for a high-quality food item, whereas they could not wait when they were required to exchange a smaller food amount for a larger amount of the same food (Auersperg et al 2013;Hillemann et al 2014;Wascher et al 2012). These same species tested in the accumulation task (in which four food items were accumulated by the experimenter at a fixed rate within reach of the subject as long as it refrained from taking the food) performed better with foods of different quality rather than with different quantities of the same food (Hillemann et al 2014).…”

To Err Is (Not Only) Human: Fallibility as a Window Into Primate Cognition

“…Three of four chimpanzees showed this pattern, reflective of self-distraction-a form of cognitive control that allowed them to deal with an apparent sense of their own fallibility in this task. Whether other species, including other primates, might employ such self-distraction techniques is not known, although there is some suggestive evidence that a grey parrot engaged in self-distraction strategies during a delay of gratification test (Koepke, Gray, & Pepperberg, 2015), and other bird species can succeed in delay of gratification tasks (e.g., Auersperg, Laumer, & Bugnyar, 2013;Hillemann, Bugnyar, Kotrschal, & Wascher, 2014).…”

Differences in persistence between dogs and wolves in an unsolvable task in the absence of humans

“…Furthermore, because food motivation is 119 known to influence problem-solving behaviour (Laland & Reader, 1999; Sol, Griffin & Bartomeus, 120 2012;Griffin, Diquelou & Perea, 2014;Griffin & Guez, 2014), we tested subjects early in the 121 5 morning without feeding them the evening prior to the test. Finally, as food motivation is influenced 122 by food quality (Fontenot et al, 2007;Dufour et al, 2012;Hillemann et al, 2014); we used high 123 value food (based on a previously performed preference test) for testing (Rao, et al in press). 124…”