Abstract: Behavioural innovations have become central to our thinking about how animals adjust to changing environments. It is now well established that animals vary in their ability to innovate, but understanding why remains a challenge. This is because innovations are rare, so studying innovation requires alternative experimental assays that create opportunities for animals to express their ability to invent new behaviours, or use pre-existing ones in new contexts. Problem solving of extractive foraging tasks has been put forward as a suitable experimental assay. We review the rapidly expanding literature on problem solving of extractive foraging tasks in order to better understand to what extent the processes underpinning problem solving, and the factors influencing problem solving, are in line with those predicted, and found, to underpin and influence innovation in the wild. Our aim is to determine whether problem solving can be used as an experimental proxy of innovation. We find that in most respects, problem solving is determined by the same underpinning mechanisms, and is influenced by the same factors, as those predicted to underpin, and to influence, innovation. We conclude that problem solving is a valid experimental assay for studying innovation, propose a conceptual model of problem solving in which motor diversity plays a more central role than has been considered to date, and provide recommendations for future research using problem solving to investigate innovation. This article is part of a Special Issue entitled: Cognition in the wild.

Abstract: Innovative problem solving enables individuals to deal with novel social and ecological challenges. However, our understanding of the importance of innovation for animals in their natural habitat is limited because experimental investigations of innovation have historically focused on captive animals. To determine how captivity affects innovation, and whether captive studies of animal innovation suffer from low external validity, we need experimental investigations of innovation in both wild and captive populations of the same species in diverse taxa. Here we inquired whether wild and captive spotted hyaenas differ in their ability to solve the same novel technical problem, and in the diversity of exploratory behaviours they exhibit when first interacting with the problem. Our results suggest that wild and captive populations show important differences in their innovative problem-solving abilities. Captive hyaenas were significantly more successful at solving the novel problem, and significantly more diverse in their initial exploratory behaviour, than were wild hyaenas. We were able to rule out hypotheses suggesting that these differences result from excess energy or time available to captive animals. We conclude that captive hyaenas were more successful because captive individuals were less neophobic and more exploratory than their wild counterparts. These results have important implications for our interpretation of studies on innovative problem solving in captive animals and aid our attempts to gain a broader understanding of the importance of innovation for animals in their natural habitat.

Abstract: Humans, chimpanzees, capuchins and aye-ayes all display an unusually high degree of encephalization and diverse omnivorous extractive foraging. It has been suggested that the high degree of encephalization in aye-ayes may be the result of their diverse, omnivorous extractive foraging behaviors. In combination with certain forms of tool use, omnivorous extractive foraging has been hypothesized to be linked to higher levels of sensorimotor intelligence (stages 5 or 6). Although free-ranging aye-ayes have not been observed to use tools directly in the context of their extractive foraging activities, they have recently been reported to use lianas as tools in a manner that independently suggests that they may possess stage 5 or 6 sensorimotor intelligence. Although other primate species which display diverse, omnivorous extractive foraging have been tested for sensorimotor intelligence, aye-ayes have not. We report a test of captive aye-ayes' comprehension of tool use in a situation designed to simulate natural conditions. The results support the view that aye-ayes do not achieve stage 6 comprehension of tool use, but rather may use trial-and-error learning to develop tool-use behaviors. Other theories for aye-aye encephalization are considered.

Abstract: Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action.