Dogs wait longer for better rewards than wolves in a delay of gratification task: but why?

Abstract

Self-control has been shown to be linked with being cooperative and successful in humans and with the g-factor in chimpanzees. As such, it is likely to play an important role in all forms of problem-solving. Self-control, however, does not just vary across individuals but seems also to be dependent on the ecological niche of the respective species. With dogs having been selected to live in the human environment, several domestication hypotheses have predicted that dogs are better at selfcontrol and thus more tolerant of longer delays than wolves. Here we set out to test this prediction by comparing dogs' and wolves' self-control abilities using a delay of gratification task where the animals had to wait for a predefined delay duration to exchange a low-quality reward for a high-quality reward. We found that in our task, dogs outperformed the wolves waiting an average of 66 s vs. 24 s in the wolves. Food quality did not influence how long the animals waited for the better reward. However, dogs performed overall better in motivation trials than the wolves, although the dogs' performance in those trials was dependent on the duration of the delays in the test trials, whereas this was not the case for the wolves. Overall, the data suggest that selection by humans for traits influencing self-control rather than ecological factors might drive self-control abilities in wolves and dogs. However, several other factors might contribute or explain the observed differences including the presence of the humans, which might have inhibited the dogs more than the wolves, lower motivation of the wolves compared to the dogs to participate in the task and/or wolves having a better understanding of the task contingencies. These possible explanations need further exploration.

Intra- and interspecific variation in self-control capacities of parrots in a delay of gratification task

“…Interestingly, similar coping behaviours have been reported also in many other species, and likewise were indicative of an enhanced waiting performance. Dogs and wolves, for example, distracted themselves with distancing themselves from the available low-quality reward, laying down and looking away (Leonardi et al 2012 ; Brucks et al 2017b ; Range et al 2020 ). Chimpanzees tolerated higher delays, if they could interact with toys during the delay (Evans and Beran 2007b ) and children waited longer, if they rested their head on their arms and closed their eyes (Steelandt et al 2012 ).…”

“…In addition to species-level differences, individual characteristics including sex (Lucon-Xiccato et al 2020), physiological measures including body condition (Shaw 2017 ) or motivation (van Horik et al 2017 ) can influence self-control. Furthermore, individuals that are able to perform distractive behaviours, otherwise known as coping behaviours, have also been shown to increase success in delay of gratification in dogs ( Canis lupus familiaris ) (Brucks et al 2017a ), wolves ( Canis lupus (Range et al 2020 ), chimpanzees ( Pan troglodytes ) (Evans and Berans 2007a ; b ), and one African grey parrot ( Psittacus erithacus ) (Koepke et al 2015 ).…”

Comparing wolves and dogs: current status and implications for human ‘self-domestication’

“…Finally, inhibitory control, which can drive differences in social cognition [103], has been hypothesized as a trait under selection during dog domestication (Synergistic Hypothesis [64]). While wolves and dogs do not differ in most inhibitory control tasks [83,104,105], dogs outperform wolves in tasks in which a human experimenter first trained the animals on an action and then stood facing them during the inhibition part of the task [103,105,106]. The presence of the human during the task might differently affect wolves and dogs, with social inhibition by humans playing a larger role in dogs than in wolves (Box 4).…”

“…While dogs are potentially less aggressive toward conspecific outgroup members (although systematic studies still need to confirm this), their ingroup social dynamics, particularly around food, have changed in less obvious ways: dominant dogs are less tolerant than are dominant wolves, and subordinate dogs (but not subordinate wolves) avoid potential conflicts where possible [69][70][71][72][73]. A similar pattern emerges when interacting with humans, where dogs appear to be more easily inhibited and more likely to comply with their demands compared with wolves (Box 4) [42,74,106,107]. Similarly, while sociability toward pack/group members does not appear to differ between wolves and dogs at the behavioral [48,49,[80][81][82] or hormonal level [49], dogs appear more inclined to engage in positive interactions with individuals that are not part of their group than do wolves [49,84].…”

Horses wait for more and better rewards in a delay of gratification paradigm

“…Nevertheless, a handful of domesticated species have been tested in delay of gratification paradigms to assess their self-control abilities. On a group level, dogs waited between four to 25 times longer (Leonardi et al, 2012;Brucks et al, 2017b;Range et al, 2020) compared to pigs (Zebunke et al, 2018;Krause et al, 2021) and chicken (Abeyesinghe et al, 2005); however, domesticated animals generally exhibited rather low self-control abilities compared to other non-domesticated species (e.g., longtailed macaques: Pelé et al, 2010;cleaner wrasse: Aellen et al, 2021). While certainly differences in experimental procedures and paradigms are accountable for some variation (Susini et al, 2021), more data on domesticated species' self-control abilities, in particular of farm animals, is needed in order to better understand whether and how domestication affected selfcontrol abilities.…”