Effect of a Cognitive Challenge Device Containing Food and Non‐Food Rewards on Chimpanzee Well‐Being

Abstract

Exploration and problem-solving are highly motivated behaviors in non-human primates, but little research has focused on whether cognitively challenging tasks can enhance primates' psychological well-being, particularly in the absence of food rewards. We evaluated whether a novel cognitive challenge device (CCD) consisting of a maze of opaque tubes enhanced the well-being of a group of six adult chimpanzees housed at ZSL Whipsnade Zoo, UK, over a two-month period. Chimpanzees had the opportunity to interact with two versions of the CCD: the first contained tokens which fell into a transparent chamber when extracted from the CCD and could not be eaten. The second contained unshelled Brazil nuts, which could be extracted and eaten. CCD-use was low over the study, occupying on average 2.5% of observation time. However, compared to baseline levels, chimpanzees exhibited more problem-solving behaviors (directed toward the CCD) and spent significantly more time engaged in social play when the CCD was present. Cage exploration was rare whether the CCD was present or not. Chimpanzees used the CCD (including tool-use) significantly more when it contained tokens. The relationship between the presence of the CCD and self-directed behavior (rough-scratching) was difficult to interpret. Although rough-scratching was significantly higher in the cage when the CCD was present and 18% of these scratching events occurred within one arm's length from the CCD, rough-scratching decreased when device use increased. This study provides a preliminary investigation of the CCD and two reward types, and suggests how the design could be modified to enhance its effects.

Cognitive enrichment and welfare: Current approaches and future directions

“…Clark and Smith (2013) found that chimpanzees exhibited more problem-solving behaviors and spent significantly more time engaged in social play when the maze was present; the maze was also used significantly more when it contained wooden tokens (which could not be physically accessed) compared with food items (nuts, which could be physically accessed). On the basis of these results, Clark and Smith (2013) felt there was some evidence for cognitive enrichment, but a small sample size (six individuals) made it difficult to draw strong conclusions. found that a group of six male dolphins spent significantly more time underwater when the underwater maze was present; it challenged cognitive skill through the stimulation of new problem-solving strategies and also stimulated social play.…”

“…Furthermore, problem-solving tasks without the incorporation of an extrinsic food reward are exceptional in a zoo setting. To address this, Clark and colleagues (Clark & Smith, 2013; designed cognitive challenges for socially-housed chimpanzees (Pan troglodytes) and bottlenose dolphins (Tursiops truncatus) that were intended to provide abstract problems (3D vertical mazes solved using the hands or rostrum respectively) and could be tested with and without extrinsic rewards. They were inspired by laboratory cognitive tests (e.g., great ape trap tubes: Martin-Ordas, Call, & Colmenares, 2008; dolphin underwater modality apparatus: e.g., Herman, 2010), rather than by examples of previous enrichment for these taxa.…”

“…They were inspired by laboratory cognitive tests (e.g., great ape trap tubes: Martin-Ordas, Call, & Colmenares, 2008; dolphin underwater modality apparatus: e.g., Herman, 2010), rather than by examples of previous enrichment for these taxa. Clark and Smith (2013) "point toward an area of research which has thus far been overlooked in zoos-in the middle-ground between highly complex and controlled laboratory tasks, and relatively simple food/object enrichment" (p. 808). Clark and Smith (2013) found that chimpanzees exhibited more problem-solving behaviors and spent significantly more time engaged in social play when the maze was present; the maze was also used significantly more when it contained wooden tokens (which could not be physically accessed) compared with food items (nuts, which could be physically accessed).…”

“…Clark and Smith (2013) "point toward an area of research which has thus far been overlooked in zoos-in the middle-ground between highly complex and controlled laboratory tasks, and relatively simple food/object enrichment" (p. 808). Clark and Smith (2013) found that chimpanzees exhibited more problem-solving behaviors and spent significantly more time engaged in social play when the maze was present; the maze was also used significantly more when it contained wooden tokens (which could not be physically accessed) compared with food items (nuts, which could be physically accessed). On the basis of these results, Clark and Smith (2013) felt there was some evidence for cognitive enrichment, but a small sample size (six individuals) made it difficult to draw strong conclusions.…”

“…The majority of captive animal enrichment uses food rewards, but in the context of cognitive enrichment, we know that some animals are motivated to seek challenge without the need for extrinsic rewards (Clark & Smith, 2013;Langbein et al, 2009). For example, Clark and Smith (2013) found that chimpanzees used a pipe maze significantly more when it contained only visibly accessible tokens compared with physically accessible Brazil nuts. The second reason why the level of challenge provided by cognitive enrichment has been fairly ad hoc so far is due to variation within and between animals.…”