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Vlamings, P. H. J. M., Uher, J., & Call, J. (2006). How the great apes (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) perform on the reversed contingency task: the effects of food quantity and food visibility. J Exp Psychol Anim Behav Process, 32(1), 60–70.
Abstract: S. T. Boysen and G. G. Berntson (1995) found that chimpanzees performed poorly on a reversed contingency task in which they had to point to the smaller of 2 food quantities to acquire the larger quantity. The authors compared the performance of 4 great ape species (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) on the reversed contingency task while manipulating food quantity (0-4 or 1-4) and food visibility (visible pairs or covered pairs). Results showed no systematic species differences but large individual differences. Some individuals of each species were able to solve the reversed contingency task. Both quantity and visibility of the food items had a significant effect on performance. Subjects performed better when the disparity between quantities was smaller and the quantities were not directly visible.
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Uher, J., Asendorpf, J. B., & Call, J. (2008). Personality in the behaviour of great apes: temporal stability, cross-situational consistency and coherence in response. Anim. Behav., 75(1), 99–112.
Abstract: Using a multidisciplinary approach, the present study complements ethological behaviour measurements with basic theoretical concepts, methods and approaches of the personality psychological trait paradigm. Its adoptability and usefulness for animal studies are tested exemplarily on a sample of 20 zoo-housed great apes (five of each of the following species): bonobos, Pan paniscus; chimpanzees, Pan troglodytes verus; gorillas, Gorilla gorilla gorilla; and orang-utans, Pongo pygmaeus abelii. Data on 76 single trait-relevant behaviours were recorded in a series of 14 laboratory-based situations and in two different group situations. Data collection was repeated completely after a break of 2 weeks within a 60-day period. All behaviour records were sufficiently reliable. Individual- and variable-oriented analyses showed high/substantial temporal stability on different levels of aggregation. Distinctive and stable individual situational and response profiles clarified the importance of situations and of multiple trait-relevant behaviours. The present study calls for a closer collaboration between behavioural biologists and personality psychologists to tap the full potential of animal personality research.
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Herrmann, E., Melis, A. P., & Tomasello, M. (2006). Apes' use of iconic cues in the object-choice task. Anim. Cogn., 9(2), 118–130.
Abstract: In previous studies great apes have shown little ability to locate hidden food using a physical marker placed by a human directly on the target location. In this study, we hypothesized that the perceptual similarity between an iconic cue and the hidden reward (baited container) would help apes to infer the location of the food. In the first two experiments, we found that if an iconic cue is given in addition to a spatial/indexical cue – e.g., picture or replica of a banana placed on the target location – apes (chimpanzees, bonobos, orangutans, gorillas) as a group performed above chance. However, we also found in two further experiments that when iconic cues were given on their own without spatial/indexical information (iconic cue held up by human with no diagnostic spatial/indexical information), the apes were back to chance performance. Our overall conclusion is that although iconic information helps apes in the process of searching hidden food, the poor performance found in the last two experiments is due to apes' lack of understanding of the informative (cooperative) communicative intention of the experimenter.
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Schwartz, B. L., Meissner, C. A., Hoffman, M., Evans, S., & Frazier, L. D. (2004). Event memory and misinformation effects in a gorilla (Gorilla gorilla gorilla). Anim. Cogn., 7(2), 93–100.
Abstract: Event memory and misinformation effects were examined in an adult male gorilla ( Gorilla gorilla gorilla). The gorilla witnessed a series of unique events, involving a familiar person engaging in a novel behavior (experiment 1), a novel person engaging in a novel behavior (experiment 2), or the presentation of a novel object (experiment 3). Following a 5- to 10-min retention interval, a tester gave the gorilla three photographs mounted on wooden cards: a photograph depicting the correct person or object and two distractor photographs drawn from the same class. The gorilla responded by returning a photograph. If correct, he was reinforced with food. Across three experiments, the gorilla performed significantly above chance at recognizing the target photograph. In experiment 4, the gorilla showed at-chance performance when the event was followed by misinformation (a class-consistent, but incorrect photograph), but significantly above-chance performance when no misinformation occurred (either correct photograph or no photograph). Although the familiarity can account for these data, they are also consistent with an episodic-memory interpretation.
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Vonk, J. (2003). Gorilla ( Gorilla gorilla gorilla) and orangutan ( Pongo abelii) understanding of first- and second-order relations. Anim. Cogn., 6(2), 77–86.
Abstract: Four orangutans and one gorilla matched images in a delayed matching-to-sample (DMTS) task based on the relationship between items depicted in those images, thus demonstrating understanding of both first- and second-order relations. Subjects matched items on the basis of identity, color, or shape (first-order relations, experiment 1) or same shape, same color between items (second-order relations, experiment 2). Four of the five subjects performed above chance on the second-order relations DMTS task within the first block of five sessions. High levels of performance on this task did not result from reliance on perceptual feature matching and thus indicate the capability for abstract relational concepts in two species of great ape.
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Schwartz, B. L., Colon, M. R., Sanchez, I. C., Rodriguez, I. A., & Evans, S. (2002). Single-trial learning of “what” and “who” information in a gorilla (Gorilla gorilla gorilla): implications for episodic memory. Anim. Cogn., 5(2), 85–90.
Abstract: Single-trial learning and long-term memory of “what” and “who” information were examined in an adult gorilla (Gorilla gorilla gorilla). We presented the gorilla with a to-be-remembered food item at the time of study. In Experiment 1, following a retention interval of either approximately 7 min or 24 h, the gorilla responded with one of five cards, each corresponding to a particular food. The gorilla was accurate on 70% of the short retention-interval trials and on 82% of the long retention-interval trials. In Experiment 2, the food stimulus was provided by one of two experimenters, each of whom was represented by a card. The gorilla identified the food (55% of the time) and the experimenter (82% of the time) on the short retention-interval trials. On the long retention-interval trials, the gorilla was accurate for the food (73%) and for the person (87%). The results are interpreted in light of theories of episodic memory.
Keywords: Animals; Cognition; Gorilla gorilla/*psychology; *Learning; Male; *Memory; Perception; Reinforcement Schedule
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Stoinski, T. S., Wrate, J. L., Ure, N., & Whiten, A. (2001). Imitative learning by captive western lowland gorillas (Gorilla gorilla gorilla) in a simulated food-processing task. J Comp Psychol, 115(3), 272–281.
Abstract: Although field studies have suggested the existence of cultural transmission of foraging techniques in primates, identification of transmission mechanisms has remained elusive. To test experimentally for evidence of imitation in the current study, we exposed gorillas (Gorilla gorilla gorilla) to an artificial fruit foraging task designed by A. Whiten and D. M. Custance (1996). Gorillas (n=6) watched a human model remove a series of 3 defenses around a fruit. Each of the defenses was removed using 1 of 2 alternative techniques. Subsequent video analysis of gorillas' behavior showed a significant tendency to copy the observed technique on 1 of the individual defenses and the direction of removal on another defense. This is the first statistically reliable evidence of imitation in gorillas. Sequence of defense removal was not replicated. The gorillas' responses were most similar to those of chimpanzees.
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Mulcahy, N. J., & Call, J. (2006). How great apes perform on a modified trap-tube task. Anim. Cogn., 9(3), 193–199.
Abstract: To date, neither primates nor birds have shown clear evidence of causal knowledge when attempting to solve the trap tube task. One factor that may have contributed to mask the knowledge that subjects may have about the task is that subjects were only allowed to push the reward away from them, which is a particularly difficult action for primates in certain problem solving situations. We presented five orangutans (Pongo pygmaeus), two chimpanzees (Pan troglodytes), two bonobos (Pan paniscus), and one gorilla (Gorilla gorilla) with a modified trap tube that allowed subjects to push or rake the reward with the tool. In two additional follow-up tests, we inverted the tube 180 degrees rendering the trap nonfunctional and also presented subjects with the original task in which they were required to push the reward out of the tube. Results showed that all but one of the subjects preferred to rake the reward. Two orangutans and one chimpanzee (all of whom preferred to rake the reward), consistently avoided the trap only when it was functional but failed the original task. These findings suggest that some great apes may have some causal knowledge about the trap-tube task. Their success, however, depended on whether they were allowed to choose certain tool-using actions.
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Gomez, J. - C. (2005). Species comparative studies and cognitive development. Trends. Cognit. Sci., 9(3), 118–125.
Abstract: The comparative study of infant development and animal cognition brings to cognitive science the promise of insights into the nature and origins of cognitive skills. In this article, I review a recent wave of comparative studies conducted with similar methodologies and similar theoretical frameworks on how two core components of human cognition--object permanence and gaze following--develop in different species. These comparative findings call for an integration of current competing accounts of developmental change. They further suggest that evolution has produced developmental devices capable at the same time of preserving core adaptive components, and opening themselves up to further adaptive change, not only in interaction with the external environment, but also in interaction with other co-developing cognitive systems.
Keywords: Animals; Attention/physiology; Brain/*growth & development; Child, Preschool; Cognition/*physiology; Concept Formation/physiology; Dogs; Evolution; Fixation, Ocular; Gorilla gorilla; Humans; Infant; Learning/*physiology; Macaca mulatta; Mental Recall/physiology; Personal Construct Theory; Psychomotor Performance/physiology; Species Specificity
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Hoff, M. P., Nadler, R. D., & Maple, T. L. (1981). Development of infant independence in a captive group of lowland gorillas. Dev Psychobiol, 14(3), 251–265.
Abstract: In March 1976, 3 lowlands gorillas (Gorilla gorilla gorilla) were born to primiparous females living with an adult male in a large compound at the field station of the Yerkes Regional Primate Research Center of Emory University. Observations of parent and infant behavior began at the birth of the infants, using several methods of data collection. This report focuses on the development of independence in these infants over the 1st 1 1/2 years of life. As expected, measures of mother-infant contact and proximity decreased with age. Several measures suggested that infant independence developed as an interactive process between mothers and infants, with primary responsibility changing over the months of study. Maternal behaviors that served to maintain mother-infant contact were found to decrease with age, with an eventual shift to infant responsibility for contact maintenance. Additionally, the adult male appeared to influence developing independence as reflected in the maternal protectiveness evoked by his behavior.
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