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von Fersen, L., & Delius, J. D. (2000). Acquired equivalences between auditory stimuli in dolphins (Tursiops truncatus). Anim. Cogn., 3(2), 79–83.
Abstract: This study investigated whether dolphins would show evidence of equivalence class formation between auditory stimuli. Bottlenose dolphins were trained to press one or other of two response levers depending on which one of four auditory stimuli had been previously presented. Once they had learned the initial discriminations, the stimulus-lever contingencies was repeatedly reversed. Within any given session, however, pressing of one lever always led to reward with one set of two tones and pressing the other lever led to non-reward with an alternative set of two tones. After sufficient experience with this response reversal procedure, the dolphins spontaneously chose the same levers they had first learned to be correct with one of the across-set stimulus pairs when later in the session they were presented with the other of the across-set stimulus pairs. They thus demonstrated that they had associated the tones belonging to the two sets within two separate functional classes. It is discussed why the dolphins succeeded with auditory stimuli when they had previously failed in a similar task with visual stimuli.
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Tomonaga, M., & Matsuzawa, T. (2000). Sequential responding to arabic numerals with wild cards by the chimpanzee (Pan troglodytes). Anim. Cogn., 3(1), 1–11.
Abstract: One adult female chimpanzee (Pan troglodytes) was trained to respond serially to three arabic numerals between 1 and 9, presented on a cathode-ray-tube (CRT) screen. To examine the factors affecting her sequential responding behavior, wild-card items were added to the three-item sequences. When this wild-card item remained until the subject responded to the last numeral (i.e., the terminator condition), her response to the terminator at each point of the sequence was controlled by the ordinal distance between numerals. Thus, the number of responses to the terminator increased as the ordinal distance between numerals increased. When the wild-card item was eliminated by the subject's response (wild-card conditions), the probability of responses to the wild card before the first numeral increased as a function of the serial position of the first numeral. These results were consistent with previous studies of response time and suggest both serial position and symbolic distance effects. It is suggested that the subject might form the integrated 9-item linear representations by training of possible subsets of three-item sequences. Knowledge concerning the ordinal position of each numeral was established through this training.
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McKinley, J., & Sambrook, T. D. (2000). Use of human-given cues by domestic dogs (Canis familiaris) and horses (Equus caballus). Anim. Cogn., 3(1), 13–22.
Abstract: Sixteen domestic dogs (Canis familiaris) and four horses (Equus caballus) were tested for their ability to use human-given manual and facial cues in an object-choice task. Two of the four horses used touch as a cue and one horse successfully used pointing. The performance of the dogs was considerably better, with 12 subjects able to use pointing as a cue, 4 able to use head orientation and 2 able to use eye gaze alone. Group analysis showed that the dogs performed significantly better in all experimental conditions than during control trials. Dogs were able to use pointing cues even when the cuer's body was closer to the incorrect object. Working gundogs with specialised training used pointing more successfully than pet dogs and gundog breeds performed better than non-gundog breeds. The results of this experiment suggest that animals' use of human given communicative signals depends on cognitive ability, the evolutionary consequences of domestication and enculturation by humans within the individual's lifetime.
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Santos LR, Hauser MD, & Spelke ES. (2001). Recognition and categorization of biologically significant objects by rhesus monkeys (Macaca mulatta): the domain of food. Cognition, 82, 127.
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Johnson, C. M. (2001). Distributed primate cognition: a review. Anim. Cogn., 3(4), 167–183.
Abstract: A model of “distributed cognition” is contrasted with the “mental representation” model exemplified by Tomasello and Call's Primate Cognition. Rather than using behavior as a basis for inferences to invisible mental events such as intentions, the distributed approach treats communicative interactions as, themselves, directly observable cognitive events. Similar to a Vygotskian approach, this model characterizes cognition as “co-constructed” by the participants. This approach is thus particularly suitable for studying primates (including humans), whose reliance on multiparty negotiations can undermine the researcher's ability to extrapolate from observable outcomes back to individual intentions. Detailed (e.g., frame-by-frame) analyses of such interactions reveal cross-species differences in the relevant media of information flow (e.g., behavioral coordination, relative gaze) as well as in the flexibility and complexity of the trajectories observed. Plus, with its focus on dynamics, the distributed approach is especially useful for modeling developmental and evolutionary processes. In discussing enculturation and the ontogeny of imitation, its emphasis is on changes in how expert and novice participate in such events, rather than how either may represent them. Primate cognitive evolution is seen as involving changes in context sensitivity, multi-tasking, and the coordination of social attention. Humans in particular – in, especially, the context of teaching – are seen as having specialized in linking co-perception with the refined sensory-motor coordination that enables them to translate observed behavior into strategically similar action. Highlighting the continuity between human and nonhuman development, this promising, complementary model enables us to tap the richness of micro-ethology as a cognitive science.
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Snowdon, C. T. (2001). Social processes in communication and cognition in callitrichid monkeys: a review. Anim. Cogn., 4(3), 247–257.
Abstract: Studies of vocal development in nonhuman primates have found little evidence for plasticity in vocal production, somewhat more for usage of calls, with the greatest plasticity arising in response to calls of others. Generally, similar results were obtained with callitrichid monkeys, the marmosets and tamarins, but with several interesting exceptions. Infant pygmy marmosets show babbling behavior with improvement in adult call structure related to the amount and diversity of babbling. Adult marmosets alter call structure in response to changes in social partners, and wild marmosets have vocal dialects and modify call structure according to how far they are from other group members, suggesting the potential to modify call structure in different social and environmental contexts, though direct learning of novel vocalizations has not been observed. Infant cotton-top tamarins do not produce adult-like calls in appropriate contexts, at least in the first few months of life, but through food sharing from adults infants learn about appropriate foods and the appropriate contexts for food vocalizations. Tamarins modify call structure and usage with changes in social status. Tamarins, unlike other monkeys tested, can learn to avoid noxious foods through observation of other group members, and can learn about novel food locations. Recent studies provide evidence of contextual imitation in marmosets. The plasticity in vocal communication and evidence of social learning in marmosets and tamarins relative to other monkeys may be related to the cooperative breeding system of marmosets and tamarins. With a high degree of behavioral coordination among group members, there is a priority on monitoring signals and behavior of others and adjusting one's own signals and behavior. This creates the context for vocal plasticity and social learning.
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Hare, B. (2001). Can competitive paradigms increase the validity of experiments on primate social cognition? Anim. Cogn., 4(3), 269–280.
Abstract: Experiments vary in their ability to distinguish between competing hypotheses. In tests on primate cognition the majority of this variation is due to an experimenter's ability to test primates in valid settings while providing the adequate amount of experimental control. While experimenters studying primate cognition can use methods of control perfected in captivity, it is still very unclear how to design and then objectively evaluate the external validity of new experimental paradigms. I recommend that more effort be allocated to specify how to create relevant test settings for primates. Primate social life is highly competitive. This means that all aspects of primates themselves, including their cognitive abilities, have likely been shaped by the need to out-compete conspecifics. Based on this hypothesis, sophisticated cognitive abilities of primates might best be demonstrated in competitive contexts. Thus, it is suggested that one possible measure of validity is whether investigators integrate a competitive component into their experimental designs. To evaluate this methodological prediction I review the literature on chimpanzee perspective-taking as a case study including several recent studies that include a competitive component in their experimental designs.
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Xitco, M., Gory, J., & Kuczaj, S. (2001). Spontaneous pointing by bottlenose dolphins (Tursiops truncatus). Anim. Cogn., 4(2), 115–123.
Abstract: Two bottlenose dolphins (Tursiops truncatus) participating in a symbolic communication project spontaneously developed behaviors that resembled pointing and gaze alternation. The dolphins' behavior demonstrated several features reminiscent of referential communicative behavior. It was triadic, involving a signaler, receiver, and referent. It was also indicative, specifying a focus of attention. The dolphins' points were distinct from the act of attending to or acting on objects. Spontaneous dolphin pointing was influenced by the presence of a potential receiver, and the distance between that receiver and the dolphin. These findings suggest that dolphins are capable of producing referential gestures.
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Brown, C. (2001). Familiarity with the test environment improves escape responses in the crimson spotted rainbowfish, Melanotaenia duboulayi. Anim. Cogn., 4(2), 109–113.
Abstract: Animals that are familiar with their environment have been reported to have greater survivorship for a number of reasons related to their knowledge of the terrain, which they recall from memory. In an initial experiment rainbowfish significantly improved their escape response towards a novel trawl apparatus over a sequence of five runs. Escape latencies were still low during a subsequent exposure 11 months after the initial exposure. While part of the improvement in escape success was certainly due to learning associated with the location of the escape route, it is likely that this was aided by habituation to the tank environment and the experimental protocol. In a follow-up experiment, fish that had been kept in the experimental tank for 3 weeks prior to testing, and had become familiar with the test tank, showed significantly lower escape latencies and escaped more often than fish that were not familiar with the test environment. It is suspected that familiarity with the testing arena decreased stress and enabled individuals to detect novel stimuli and devote more attention to them. These findings have significant implications for experimenters studying aspects of animal cognition, such as learning and memory, in laboratory situations.
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Tanaka, M. (2001). Discrimination and categorization of photographs of natural objects by chimpanzees (Pan troglodytes). Anim. Cogn., 4(3), 201–211.
Abstract: Two experiments assessed the ability of four adult female chimpanzees to categorize natural objects. Chimpanzees were initially trained to match different color photographs of familiar objects from four possible categories. In training, all the comparison stimuli were from the same category in one condition, and from different categories in another condition. For all subjects, training performance was consistently better for the “different category” than for the “same category” trials. Probe trials were shown after training. In probe trials, the sample and positive comparison stimuli were different items from the same category, and the foils were selected from among the three other test categories. Individual performance was above chance in probe trials, suggesting that categorization by chimpanzees may transcend perceptual resemblance. These results were later replicated with novel stimulus items from the same four categories (experiment 2). Altogether, this research demonstrates that chimpanzees grouped perceptually different exemplars within the same category, and further suggests that these animals formed conceptual representations of the categories.
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