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Schwartz, B. L., & Evans, S. (2001). Episodic memory in primates. Am. J. Primatol., 55(2), 71–85.
Abstract: Episodic memory refers to a system of memory with the capacity to recollect specific events from an individual's life. Some psychologists have suggested that episodic memory is a uniquely human phenomenon. We challenge that idea and present evidence that great apes and other primates may possess episodic-like memory. We review criteria developed to assess episodic-like memory in nonhumans, and how they apply to primates. In particular, we discuss the criteria of Clayton et al. [2001], who stated that episodic-like memory is based on the retrieval of multiple and integrated components of an event. We then review eight studies examining memory in great apes and apply the Clayton et al. criteria to each of them. We summarize the evidence that is compatible with the existence of episodic-like memory, although none of the data completely satisfy the Clayton et al. criteria. Morover, feelings of pastness and feelings of confidence, which mark episodic memory in humans, have not been empirically addressed in nonhuman primates. Future studies should be directed at these aspects of memory in primates. We speculate on the functional significance of episodic memory in nonhuman primates.
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Martin, T. I., & Zentall, T. R. (2005). Post-choice information processing by pigeons. Anim. Cogn., 8(4), 273–278.
Abstract: In a conditional discrimination (matching-to-sample), a sample is followed by two comparison stimuli, one of which is correct, depending on the sample. Evidence from previous research suggests that if the stimulus display is maintained following an incorrect response (the so-called penalty-time procedure), acquisition by pigeons is facilitated. The present research tested the hypothesis that the penalty-time procedure allows the pigeons to review and learn from the maintained stimulus display following an incorrect choice. It did so by including a penalty-time group for which, following an incorrect choice, the sample changed to match the incorrect comparison, thus providing the pigeons with post-choice 'misinformation.' This misinformation group acquired the matching task significantly slower than the standard penalty-time group (that had no change in the sample following an error). Furthermore, acquisition of matching by a control group that received no penalty time fell midway between the other two groups, suggesting that the pigeons did not merely take more care in making choices because of the aversiveness of penalty-time. Thus, it appears that in the acquisition of matching-to-sample, when the stimulus display is maintained following an incorrect choice, the pigeons can review or acquire information from the display. This is the first time that such an effect has been reported for a nonhuman species.
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Zentall, T. R. (2005). Configural/holistic processing or differential element versus compound similarity. Anim. Cogn., 8(2), 141–142.
Abstract: Before accepting a configural or holistic account of visual perception, one should be sure that an analytic (elemental) account does not provide an equal or better explanation of the results. I suggest that when one forms a compound of a color and a line orientation with one element previously trained as an S+ and the other as an S-, the resulting transfer found will depend on the relative salience of the two elements, and most important, the similarity of the compound to each of the training stimuli. Thus, if a line orientation is placed on a colored background (a separable compound), it will appear more like the colored field used in training, and color will control responding. However, if the line itself is colored (an integral compound), the compound will appear more like the line used in training, and line orientation will control responding. Not only does this account do a better job of explaining the data but it is simpler and it is testable.
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Agrillo, C., Dadda, M., & Bisazza, A. (2007). Quantity discrimination in female mosquitofish. Anim. Cogn., 10(1), 63–70.
Abstract: The ability in animals to count and represent different numbers of objects has received a great deal of attention in the past few decades. Cumulative evidence from comparative studies on number discriminations report obvious analogies among human babies, non-human primates and birds and are consistent with the hypothesis of two distinct and widespread mechanisms, one for counting small numbers (<4) precisely, and one for quantifying large numbers approximately. We investigated the ability to discriminate among different numerosities, in a distantly related species, the mosquitofish, by using the spontaneous choice of a gravid female to join large groups of females as protection from a sexually harassing male. In one experiment, we found that females were able to discriminate between two shoals with a 1:2 numerosity ratio (2 vs. 4, 4 vs. 8 and 8 vs. 16 fish) but failed to discriminate a 2:3 ratio (8 vs. 12 fish). In the second experiment, we studied the ability to discriminate between shoals that differed by one element; females were able to select the larger shoal when the paired numbers were 2 vs. 3 or 3 vs. 4 but not 4 vs. 5 or 5 vs. 6. Our study indicates that numerical abilities in fish are comparable with those of other non-verbal creatures studied; results are in agreement with the hypothesis of the existence of two distinct systems for quantity discrimination in vertebrates.
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Kitchen, D. M., Cheney, D. L., & Seyfarth, R. M. (2005). Male chacma baboons (Papio hamadryas ursinus) discriminate loud call contests between rivals of different relative ranks. Anim. Cogn., 8(1), 1–6.
Abstract: Males in multi-male groups of chacma baboons (Papio hamadryas ursinus) in Botswana compete for positions in a linear dominance hierarchy. Previous research suggests that males treat different categories of rivals differently; competitive displays between males of similar rank are more frequent and intense than those between disparately ranked males. Here we test whether males also respond differently to male-male interactions in which they are not directly involved, using playbacks of the loud 'wahoo' calls exchanged between competing males in aggressive displays. We played paired sequences of vocal contests between two adjacently ranked and two disparately ranked males to ten subjects, half ranking below the signalers in the call sequences and half above. Subjects who ranked above the two signalers showed stronger responses than lower-ranking subjects. Higher-ranking subjects also responded more strongly to sequences involving disparately ranked, as opposed to adjacently ranked opponents, suggesting that they recognized those individuals' relative ranks. Strong responses to sequences between disparately ranked opponents might have occurred either because such contests typically involve resources of high fitness value (defense of meat, estrous females or infants vulnerable to infanticide) or because they indicate a sudden change in one contestant's condition. In contrast, subjects who ranked lower than the signalers responded equally strongly to both types of sequences. These subjects may have been able to distinguish between the two categories of opponents but did not respond differently to them because they had little to lose or gain by a rank reversal between males that already ranked higher than they did.
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Caldwell, C. A., & Whiten, A. (2004). Testing for social learning and imitation in common marmosets, Callithrix jacchus, using an artificial fruit. Anim. Cogn., 7(2), 77–85.
Abstract: We tested for social learning and imitation in common marmosets using an artificial foraging task and trained conspecific demonstrators. We trained a demonstrator marmoset to open an artificial fruit, providing a full demonstration of the task to be learned. Another marmoset provided a partial demonstration, controlling for stimulus enhancement effects, by eating food from the outside of the apparatus. We thus compared three observer groups, each consisting of four animals: those that received the full demonstration, those that received the partial demonstration, and a control group that saw no demonstration prior to testing. Although none of the observer marmosets succeeded in opening the artificial fruit during the test periods, there were clear effects of demonstration type. Those that saw the full demonstration manipulated the apparatus more overall, whereas those from the control group manipulated it the least of the three groups. Those from the full-demonstration group also contacted the particular parts of the artificial fruit that they had seen touched (localised stimulus enhancement) to a greater extent than the other two groups. There was also an interaction between the number of hand and mouth touches made to the artificial fruit for the full- and partial-demonstration groups. Whether or not these data represent evidence for imitation is discussed. We also propose that the clear differences between the groups suggest that social learning mechanisms provide real benefits to these animals in terms of developing novel food-processing skills analogous to the one presented here.
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Tanaka, M. (2007). Recognition of pictorial representations by chimpanzees (Pan troglodytes). Anim. Cogn., 10(2), 169–179.
Abstract: In this study, I investigated chimpanzees' ability to recognize pictorial representations. Four adults and three juvenile chimpanzees were trained to choose images of photographs of flowers among 12 items belonging to four categories on a touch-sensitive monitor. As a generalization test, the following five types of images were presented: (1) novel photographs, (2) colored sketches (more realistic), (3) a colored clip art (cartoon-like images), (4) black-and-white line drawings, and (5) Kanji characters (as the control images). One adult and all three juvenile chimpanzees were able to choose any style of the nonphotographic images of flowers significantly above the chance level, whereas none could choose the correct Kanji characters corresponding to a flower significantly above the chance level. The other three adult chimpanzees' performance level did not exceed the chance level in terms of choosing nonphotographic images although they showed good transfer skills to novel photographs. The results revealed that not all chimpanzees could recognize pictures used by humans without training. The results also suggest “critical period” in acquisition of skill in recognizing pictures in chimpanzees. Only one adult chimpanzee, who had acquired skill in recognizing visual symbols, also recognized pictures aside from the juvenile chimpanzees. Her learning history might have aided her in acquiring this skill. The results of this study suggest a relationship between pictorial competence and symbolic one.
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Topál, J., Byrne, R. W., Miklósi, Á., & Csányi, V. (2006). Reproducing human actions and action sequences: “Do as I Do!” in a dog. Anim. Cogn., 9(4), 355–367.
Abstract: We present evidence that a dog (Philip, a 4-year-old tervueren) was able to use different human actions as samples against which to match his own behaviour. First, Philip was trained to repeat nine human-demonstrated actions on command ('Do it!'). When his performance was markedly over chance in response to demonstration by one person, testing with untrained action sequences and other demonstrators showed some ability to generalise his understanding of copying. In a second study, we presented Philip with a sequence of human actions, again using the 'Do as I do' paradigm. All demonstrated actions had basically the same structure: the owner picked up a bottle from one of six places; transferred it to one of the five other places and then commanded the dog ('Do it!'). We found that Philip duplicated the entire sequence of moving a specific object from one particular place to another more often than expected by chance. Although results point to significant limitations in his imitative abilities, it seems that the dog could have recognized the action sequence, on the basis of observation alone, in terms of the initial state, the means, and the goal. This suggests that dogs might acquire abilities by observation that enhance their success in complex socio-behavioural situations.
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Watanabe, S., & Troje, N. F. (2006). Towards a “virtual pigeon”: a new technique for investigating avian social perception. Anim. Cogn., 9(4), 271–279.
Abstract: The purpose of the present study is to examine the applicability of a computer-generated, virtual animal to study animal cognition. Pigeons were trained to discriminate between movies of a real pigeon and a rat. Then, they were tested with movies of the computer-generated (CG) pigeon. Subjects showed generalization to the CG pigeon, however, they also responded to modified versions in which the CG pigeon was showing impossible movement, namely hopping and walking without its head bobbing. Hence, the pigeons did not attend to these particular details of the display. When they were trained to discriminate between the normal and the modified version of the CG pigeon, they were able to learn the discrimination. The results of an additional partial occlusion test suggest that the subjects used head movement as a cue for the usual vs. unusual CG pigeon discrimination.
Keywords: Animals; Behavioral Research/instrumentation/methods; Columbidae/*physiology; Computer Graphics; *Computer Simulation; Discrimination Learning/*physiology; Generalization (Psychology)/*physiology; Pattern Recognition, Visual/*physiology; Perceptual Masking/physiology; Rats; Recognition (Psychology)/physiology; *Social Behavior; User-Computer Interface
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Call, J. (2006). Inferences by exclusion in the great apes: the effect of age and species. Anim. Cogn., 9(4), 393–403.
Abstract: This study investigated the ability of chimpanzees, gorillas, orangutans, and bonobos to make inferences by exclusion using the procedure pioneered by Premack and Premack (Cognition 50:347-362, 1994) with chimpanzees. Thirty apes were presented with two different food items (banana vs. grape) on a platform and covered with identical containers. One of the items was removed from the container and placed between the two containers so that subjects could see it. After discarding this item, subjects could select between the two containers. In Experiment 1, apes preferentially selected the container that held the item that the experimenter had not discarded, especially if subjects saw the experimenter remove the item from the container (but without seeing the container empty). Experiment 3 in which the food was removed from one of the containers behind a barrier confirmed these results. In contrast, subjects performed at chance levels when a stimulus (colored plastic chip: Exp. 1; food item: Exp. 2 and Exp. 3) designated the item that had been removed. These results indicated that apes made inferences, not just learned to use a discriminative cue to avoid the empty container. Apes perceived and treated the item discarded by the experimenter as if it were the very one that had been hidden under the container. Results suggested a positive relationship between age and inferential ability independent of memory ability but no species differences.
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