Innovative problem solving in nonhuman animals: the effects of group size revisited

Abstract

Sociality is associated with a variety of costs and benefits, one of which can be to increase the likelihood of individuals solving novel problems. Several hypotheses explaining why groups show higher innovative problem-solving efficiencies than individuals alone have been proposed including the sharing of antipredator vigilance and the pool-of-competence effect, whereby larger groups containing a more diverse range of individuals are more likely to contain individuals with the skills necessary to solve the particular problem at hand. Interference between group members may cause groups to have lower problem solving abilities, however. Using a simulation approach, we model the shape of the relationship between group-level problem-solving probability and group size across a range of facilitation and inhibition scenarios, various population distributions of problem solving, and a task requiring 1 action or 2 actions to be solved. Simulations showed that both sharing of antipredator vigilance and the addition of competent individuals to an existing group lead to positive relationships between group-level problem solving and group size that reach 100% solving probability, whereas interference effects generate group-solving probabilities that rise to a maximum and decrease again, generating a group size for which problem solving is maximized. In contrast, both inhibition and facilitation scenarios generate identical patterns of individual efficiencies. Our results have important implications for our ability to understand the mechanisms that underpin group-size effects on problem solving in nonhumans.

Larger group sizes facilitate the emergence and spread of innovations in a group-living bird

“…Explanations other than the skill pool hypothesis have been suggested for the observed relationships between group size and the emergence of innovative behaviour. For instance, positive relationships could be the result of an antipredator vigilance effect in larger groups, allowing more time for exploration and innovative behaviour (Griffin & Guez, 2015). During our experimental trials we recorded no antipredator behaviour (e.g.…”

“…Much of the evidence supporting a positive relationship between group size and problem-solving performance comes from studies on humans (Clément et al., 2013, Laughlin et al., 2006). Evidence of this relationship in nonhuman animals is limited to a handful of studies, and has produced equivocal results (reviewed by Griffin & Guez, 2015). Some studies report positive effects of group size (Liker and Bókony, 2009, Morand-Ferron and Quinn, 2011), whereas others report negative effects (Griffin et al., 2013, Overington et al., 2009) or no effect (Thornton and Malapert, 2009a, Thornton and Samson, 2012).…”

“…A number of potential factors may generate a positive relationship between group size and the emergence of behavioural innovations. For instance, the presence of more group members may reduce neophobia and the need to invest in antipredator vigilance, facilitating the exploitation of novel foraging resources (Griffin and Guez, 2015, Visalberghi and Addessi, 2000; but see; Stöwe, Bugnyar, Heinrich, & Kotrschal, 2006). Alternatively, studies of captive house sparrows, Passer domesticus (Liker & Bókony, 2009) and wild flocks of great tits, Parus major (Morand-Ferron & Quinn, 2011) have argued in favour of the ‘skill pool’ or ‘pool of competence’ hypothesis, whereby group size effects on innovation are driven by greater phenotypic diversity within larger groups (Giraldeau, 1984, Giraldeau and Lefebvre, 1986).…”

Captive jays exhibit reduced problem-solving performance compared to wild conspecifics

“…One explanation for the poorer problem-solving performance of captive jays is that these individuals may have been trying to remain vigilant to possible danger in the new environment. Previous studies have found that vigilance behaviours increase as group size decreases [45–47]. We did not quantify vigilance behaviours, but it is possible that jay subjects in groups of two in captivity increased vigilance behaviours like visual scanning when near the food source (puzzle box), compared to wild conspecifics that could be near up to nine vigilant group-mates.…”

Cognitive performance is linked to group size and affects fitness in Australian magpies

“…Cognitive performance was measured as the number of trials taken to pass the task. In addition to the potential cognitive demands of living in larger social groups, it is possible that indirect effects of group size on energy intake and task attention could generate group size effects on cognitive performance 41,42. We therefore included neophobia (defined as the time taken to interact with the task once being within 5m of it), body mass, and foraging efficiency as explanatory terms in the analysis, as well as sex, the sex ratio of males to females in the group, the order tested within the group, and group size.…”