Problem solving in great apes (Pan paniscus, Pan troglodytes, Gorilla gorilla, and Pongo abelii): the effect of visual feedback (original) (raw)
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Animal Cognition, 2011
Humans are able to beneWt from a causally structured problem-solving context rather than arbitrarily structured situations. In order to better understand nonhuman causal cognition, it is therefore important to isolate crucial factors that might diVerentiate between events that follow a purely spatial and temporal contingency and those that hold a "true" causal relationship. In the Wrst of two experiments, chimpanzee subjects were required to detect a bottle containing juice from Wve opaque bottles of equal shape and size. In the causal condition, the juice bottle looked identical to the other four bottles, only it was much heavier than the others. In the arbitrary condition, the weight of all Wve bottles was identical, but the juice bottle was color-marked diVerently. Since bottle opening was made diYcult (and therefore costly), the question was whether subject's manipulative behavior would be random or somehow inXuenced by the nature of the provided information. Our results show that subjects detected and opened the juice bottle signiWcantly faster when weight was the discriminating feature (causal condition) compared to situations in which the discrimination was necessarily based on a color-cue (arbitrary condition). Experiment 2 ruled out the possibility of a general learning bias toward tactile rather than visual information in chimpanzees. When tested in a simple exchange paradigm that prevented any use of causal information, no predominance of a tactile cue (weight) over a visual cue (color) could be found. Furthermore-and in contrast to the causal condition in Experiment 1-no learning occurred during the course of Experiment 2, neither in the weight nor in the color condition. We therefore conclude that chimpanzees can more easily determine the content of an object based on its causal properties compared to situations in which the only available information is a pure arbitrary regularity. This supports the view that chimpanzees' causal cognition does not rely on mere perceptual information but also on structural abstraction about their physical environment.
The cognitive underpinnings of flexible tool use in great apes
Journal of Experimental Psychology: Animal Learning and Cognition, 2014
Nonhuman primates perform poorly in trap tasks, a benchmark test of causal knowledge in nonhuman animals. However, recent evidence suggests that when the confound of tool-use is avoided, great apes' performance improves dramatically. In the present study, we examined the cognitive underpinnings of tool-use that contribute to apes' poor performance in trap tasks. We presented chimpanzees (Pan troglodytes), bonobos (Pan paniscus), and orangutans (Pongo abelii) with different versions of a maze-like, multilevel trap task. We manipulated whether the apes had to use their fingers or a stick to negotiate a reward through the maze. Furthermore, we varied whether the apes got visual information about the functionality of the traps (i.e. blockage of free passage) or only arbitrary color stimuli indicating the location of the traps. We found that apes in the finger-maze task outperformed apes in the tool-use-maze task (and partially planned their moves multiple steps ahead) and (2) tool-using apes failed to learn to avoid the traps and performed similar to apes that did not get functional information about the traps. Follow-up experiments with apes that already had learnt to avoid the traps showed that tool-use or the color cues per se did not pose a problem for experienced apes. These results suggest that simultaneously monitoring two spatial relations (tool-reward and reward-surface of the apparatus) might overstrain apes' cognitive system. Thus, trap tasks involving tool-use might constitute a dual task loading on the same cognitive resources; a candidate for these shared resources is the attentional system.
Abstract Knowledge in the Broken-String Problem: Evidence from Nonhuman Primates and Pre-Schoolers
PLoS ONE, 2014
There is still large controversy about whether abstract knowledge of physical problems is uniquely human. We presented 9 capuchin monkeys, 6 bonobos, 6 chimpanzees and 48 children with two versions of a broken-string problem. In the standard condition, participants had to choose between an intact and a broken string as means to a reward. In the critical condition, the functional parts of the strings were covered up and replaced by perceptually similar, but non-functional cues. Apes, monkeys and young children performed significantly better in the standard condition in which the cues played a functional role, indicating knowledge of the functional properties involved. Moreover, a control experiment with chimpanzees and young children ruled out that this difference in performance could be accounted for by differences of perceptual feedback in the two conditions. We suggest that, similar to humans, nonhuman primates partly rely on abstract concepts in physical problem-solving.
Barriers and traps: great apes’ performance in two functionally equivalent tasks
Animal Cognition, 2012
Tool-using tasks that require subjects to overcome the obstacles to get a reward have been a major component of research investigating causal knowledge in primates. Much of the debate in this research has focused on whether subjects simply use certain stimulus features or instead use more functionally relevant information regarding the eVect that certain features may have on a moving reward. Here, we presented two obstacle tasks, a trap platform and a barrier platform, to 22 great apes. Although perceptually similar, these two tasks contain two perceptually diVerent but functionally equivalent obstacles: a trap and a barrier. In a pre-exposure phase, subjects either experienced an obstacle task or a task without any obstacle. In the transfer phase, all subjects were presented with an obstacle task, either the trap platform or the barrier platform. Our results show that those subjects who received an obstacle task prior to the second task performed better than those who Wrst received a non-obstacle task. The type of obstacle task that subjects received Wrst did not have any eVect on their performance in the transfer phase. We suggest that apes possess some knowledge about the eVects that obstacles have on slow-moving unsupported objects.
Animal Cognition, 2008
Previous studies on tool using have shown that presenting subjects with certain modiWcations in the experimental setup can substantially improve their performance. However, procedural modiWcations (e.g. trap table task) may not only remove task constraints but also simplify the problem conceptually. The goal of this study was to design a variation of the trap-table that was functionally equivalent to the trap-tube task. In this new task, the subjects had to decide where to insert the tool and in which direction the reward should be pushed. We also administered a trap-tube task that allowed animals to push or rake the reward with the tool to compare the subjects' performance on both tasks. We used a larger sample of subjects than in previous studies and from all the four species of great apes (Gorilla gorilla, Pan troglodytes, Pan paniscus, and Pongo pygmaeus). The results showed that apes performed better in the trap-platform task than in the trap-tube task. Subjects solved the tube task faster than in previous studies and they also preferred to rake in rather than to push the reward out. There was no correlation in the level of performance between both tasks, and no indication of interspecies diVerences. These data are consistent with the idea that apes may possess some speciWc causal knowledge of traps but may lack the ability to establish analogical relations between functional equivalent tasks.
Raising the level: orangutans solve the floating peanut task without visual feedback
Primates; journal of primatology, 2021
Chimpanzees and orangutans are able to generate innovative behaviors to solve complicated physical problems. For example, when presented with an out-of-reach peanut at the bottom of a vertical tube (floating peanut task-FPT), some of them spontaneously spit water into the tube until the peanut floats to the top. Yet, it is unclear whether this innovative solution results from repeating those actions that bring the peanut incrementally closer to the top or from anticipating the solution before acting. In the current study, we addressed this question by presenting three naïve orangutans with an opaque version of the FPT that prevented them from obtaining visual information about the effect of their actions on the position of the peanut. One of the subjects solved the opaque FPT in the very first trial: he collected water from the faucet and poured it into the opaque tube repeatedly until the hitherto non-visible peanut reached the top. This provides evidence for the first time that or...
Comprehension of cause€ffect relations in a tool-using task by chimpanzees (Pan troglodytes)
Journal of Comparative Psychology, 1995
Five chimpanzees (Pan troglodytes) were tested to assess their understanding of causality in a tool task. The task consisted of a transparent tube with a trap-hole drilled in its middle. A reward was randomly placed on either side of the hole. Depending on which side the chimpanzee inserted the stick into, the candy was either pushed out of the tube or into the trap. In Experiment 1, the success rate of 2 chimpanzees rose highly above chance, but that of the other subjects did not. Results show that the 2 successful chimpanzees selected the correct side for insertion beforehand. Experiment 2 ruled out the possibility that their success was due to a distance-based associative rule, and the results favor an alternative hypothesis that relates success to an understanding of the causal relation between the toolusing action and its outcome.
Assessing Generalization Within and Between Trap Tasks in the Great Apes
2009
Considerable research has been devoted to investigate the type of information that subjects use to solve tool-using tasks in which they have to avoid certain obstacles (e.g., traps) to retrieve a reward. Much of the debate has centered on whether subjects simply use certain stimulus features (e.g., the position of the trap) or instead use more functionally-relevant information regarding the effect that certain features may have on a moving reward. We tested eight apes (that in a previous study had succeeded in a trap-tube task) with one functional and two nonfunctional traps to investigate the features that they used to solve the task. Four of the eight subjects used functional features. Additionally, we presented 31 apes with a trap task that did not involve tools but required subjects to make an inference about the position of a hidden reward based on its displacement over a substrate with or without a trap. Subjects performed above chance levels (including from the first trial) in the experimental condition (unlike in the control conditions), suggesting that they took into account the effect that a trap may have on a reward. Third, we correlated the subjects performance in four trap tasks (3 involving tool-use and one without tool-use) and found positive correlations between some of the tasks. Our results suggest that apes possess some knowledge about the effects that traps have on slow moving unsupported objects. However, this knowledge was not robust enough to prevent the influence of certain practice and task effects. Moreover, subjects' knowledge may not have been abstract enough to allow them to establish broad analogies between tasks.
Journal of Experimental Child Psychology, 2015
When presented with the broken cloth problem, both human children and nonhuman great apes prefer to pull a continuous cloth over a discontinuous cloth in order to obtain a desired object resting on top. This has been interpreted as evidence that they preferentially attend to the functionally relevant cues of the task (e.g., presence or absence of a gap along the cloth). However, there is controversy regarding whether great apes' behavior is underpinned by causal knowledge, involving abstract concepts (e.g., support, connection), or by perceptual knowledge, based on percepts (e.g., contact, continuity). We presented chimpanzees, orangutans, and 2-, 3-, and 4-year-old children with two versions of the broken cloth problem. The Real condition, made with paper strips, could be solved based on either perceptual cues or causal knowledge. The Painted condition, which looked very similar, could be solved only by attending to perceptual cues. All groups mastered the Real condition, in line with previous results. Older children (3and 4-year-olds) performed significantly better in this condition than all other groups, but the performance of apes and children did not differ sharply, with 2-year-olds and apes obtaining similar results. In contrast, only 4-year-olds solved the Painted condition.