Innovative problem solving in great apes: the role of visual feedback in the floating peanut task

Abstract

Nonhuman great apes show remarkable behavioural flexibility. Some individuals are even able to use water as a tool: They spit water into a vertical tube to make a peanut float upwards until it comes into reach (floating peanut task; FPT). In the current study, we used the FPT to investigate how visual feedback, an end-state demonstration and a social demonstration affect task performance in nonhuman great apes in three experiments. Our results indicate that apes who had acquired the solution with a clear tube maintained it with an opaque one. However, apes starting with an opaque tube failed to solve the task. Additionally, facing the peanut floating on a water-filled tube (i.e., an end-state demonstration) promoted success independent on the availability of visual feedback. Moreover, experiencing how water was poured into the tube either by a human demonstrator or by a water tap that had been opened either by the ape or a human did not seem to be of further assistance. First, this study suggests that great apes require visual feedback for solving the FPT, which is no longer required after the initial acquisition. Second, some subjects benefit from encountering the end-state, a finding corroborating previous studies. Electronic supplementary material The online version of this article (10.1007/s10071-019-01275-0) contains supplementary material, which is available to authorized users.

A review of research in primate sanctuaries

“…However, researchers have also investigated several more specific topics with sanctuary-housed chimpanzees, such as the influence of both social presence [164] and early rearing history [165] on problem-solving. Other problemsolving research has looked at chimpanzees' use of causal and arbitrary cues [166] as well as the role of visual feedback in the floating peanut task [167]. The performance of chimpanzees at Ngamba on the floating peanut task has also been studied comparatively with human children and nonsanctuary-housed gorillas (Gorilla gorilla gorilla) and orangutans (Pongo pygmaeus) [168].…”

“…As in other settings, the methods to study cognition in sanctuaries are highly varied, ranging from puzzles [129,138,167,168] to video playbacks of conspecifics [181]. Among the most common studies, in both range-and non-royalsocietypublishing.org/journal/rsbl Biol.…”

Bornean Orangutans (Pongo pygmaeus pygmaeus) Use Water as a Tool in the Floating Object Task

“…Tennie et al (2010) concluded that the observational learning, specifically emulation, increased the success of the chimpanzees. Ebel et al (2019) found that none of the 24 sanctuary-living chimpanzees in Experiment 1 solved the task with an opaque tube, although one chimpanzee solved the task after viewing a water-filled tube with a peanut floating on top (end-state condition). In Experiment 2, five out of 18 zoo-living chimpanzees (28%, 13 of 18 had failed to solve the task in a previous study) and none of the six bonobos they tested solved the floating object task (Ebel et al, 2019).…”

“…Ebel et al (2019) found that none of the 24 sanctuary-living chimpanzees in Experiment 1 solved the task with an opaque tube, although one chimpanzee solved the task after viewing a water-filled tube with a peanut floating on top (end-state condition). In Experiment 2, five out of 18 zoo-living chimpanzees (28%, 13 of 18 had failed to solve the task in a previous study) and none of the six bonobos they tested solved the floating object task (Ebel et al, 2019). In Experiment 3, six of eight chimpanzees and four of five Sumatran orangutans that previously succeeded on the task solved it in a re-test (Ebel et al, 2019).…”

“…In Experiment 2, five out of 18 zoo-living chimpanzees (28%, 13 of 18 had failed to solve the task in a previous study) and none of the six bonobos they tested solved the floating object task (Ebel et al, 2019). In Experiment 3, six of eight chimpanzees and four of five Sumatran orangutans that previously succeeded on the task solved it in a re-test (Ebel et al, 2019). Seven brown capuchin monkeys presented with the floating object task were unable to spontaneously solve the task, but after viewing a human model pour water into the tube, one monkey obtained the reward using a wad of straw instead of water (Renner et al, 2017).…”