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Hobaiter, C., & Byrne, R. (2011). Serial gesturing by wild chimpanzees: its nature and function for communication. Anim. Cogn., 14(6), 827–838.
Abstract: Chimpanzees at Budongo, Uganda, regularly gesture in series, including ‘bouts’ of gesturing that include response waiting and ‘sequences’ of rapid-fire gesturing without pauses. We examined the distribution and correlates of 723 sequences and 504 bouts for clues to the function of multigesture series. Gesturing by older chimpanzees was more likely to be successful, but the success rate of any particular gesture did not vary with signaller age. Rather, older individuals were more likely to choose successful gestures, and these highly successful gestures were more often used singly. These patterns explain why bouts were recorded most in younger animals, whereas older chimpanzees relied more on single gestures: bouts are best interpreted as a consequence of persistence in the face of failure. When at least one gesture of a successful type occurred in a sequence, that sequence was more likely to be successful; overall, however, sequences were less successful than single gestures. We suggest that young chimpanzees use sequences as a ‘fail-safe’ strategy: because they have the innate potential to produce a large and redundant repertoire of gestures but lack knowledge of which of them would be most efficient. Using sequences increases the chance of giving one effective gesture and also allows users to learn the most effective types. As they do so, they need to use sequences less; sequences may remain important for subtle interpersonal adjustment, especially in play. This ‘Repertoire Tuning’ hypothesis explains a number of results previously reported from chimpanzee gesturing.
Keywords: Biomedizin & Life Sciences
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Cinková, I., & Policht, R. (2016). Sex and species recognition by wild male southern white rhinoceros using contact pant calls. Anim. Cogn., 19(2), 375–386.
Abstract: Recognition of information from acoustic signals is crucial in many animals, and individuals are under selection pressure to discriminate between the signals of conspecifics and heterospecifics or males and females. Here, we first report that rhinos use information encoded in their calls to assess conspecifics and individuals of closely related species. The southern (Ceratotherium simum) and critically endangered northern (C. cottoni) white rhinos are the most social out of all the rhinoceros species and use a contact call pant. We found that southern white rhino pant calls provide reliable information about the caller’s sex, age class and social situation. Playback experiments on wild territorial southern white rhinoceros males revealed that they responded more strongly to the pant calls of conspecific females compared to the calls of other territorial males. This suggests that pant calls are more important form of communication between males and females than between territorial males. Territorial southern males also discriminated between female and territorial male calls of northern species and reacted more intensively to the calls of northern than southern males. This might be caused by a novelty effect since both species naturally live in allopatry. We conclude that white rhinos can directly benefit from assessing individuals at long distances using vocal cues especially because their eyesight is poor. Pant calls thus likely play a significant role in their social relationships and spatial organization. In addition, better understanding of vocal communication in white rhinos might be helpful in conservation management particularly because of their low reproduction in captivity.
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Koba, R., & Izumi, A. (2006). Sex categorization of conspecific pictures in Japanese monkeys (Macaca fuscata). Anim. Cogn., 9(3), 183–191.
Abstract: We investigated whether monkeys discriminate the sex of individuals from their pictures. Whole-body pictures of adult and nonadult monkeys were used as stimuli. Two male Japanese monkeys were trained for a two-choice sex categorization task in which each of two choice pictures were assigned to male and female, respectively. Following the training, the monkeys were presented with novel monkey pictures, and whether they had acquired the categorization task was tested. The results suggested that while monkeys discriminate between the pictures of adult males and females, discrimination of nonadult pictures was difficult. Partial presentations of the pictures showed that conspicuous and sexually characteristic parts (i.e., underbellies including male scrotums or breasts including female nipples) played an important role in the sex categorization.
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Saucier, D. M., Shultz, S. R., Keller, A. J., Cook, C. M., & Binsted, G. (2007). Sex differences in object location memory and spatial navigation in Long-Evans rats. Anim. Cogn., .
Abstract: In both humans and rodents, males typically excel on a number of tasks requiring spatial ability. However, human females exhibit advantages in memory for the spatial location of objects. This study investigated whether rats would exhibit similar sex differences on a task of object location memory (OLM) and on the watermaze (WM). We predicted that females should outperform males on the OLM task and that males should outperform females on the WM. To control for possible effects of housing environment, rats were housed in either complex environments or in standard shoebox housing. Eighty Long-Evans rats (40 males and 40 females) were housed in either complex (Complex rats) or standard shoebox housing (Control rats). Results indicated that males had superior performance on the WM, whereas females outperformed males on the OLM task, regardless of housing environment. As these sex differences cannot be easily attributed to differences in cognitive style related to linguistic processing of environmental features or to selection pressures related to the hunting gathering evolutionary prehistory of humans, these data suggest that sex differences in spatial ability may be related to traits selected for by polygynous mating strategies.
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Astié, A. A., Kacelnik, A., & Reboreda, J. C. (1998). Sexual differences in memory in shiny cowbirds. Anim. Cogn., 1(2), 77–82.
Abstract: Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male's assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood.
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Gabor, V., & Gerken, M. (2014). Shetland ponies (Equus caballus) show quantity discrimination in a matching-to-sample design. Anim. Cogn., 17(6), 1233–1243.
Abstract: Numerical competence is one of the aspects of animal cognition with a long history of research interest, but few results are available for the horse. In the present study, we investigated the ability of three Shetland ponies to discriminate between different quantities of geometric symbols presented on a computer screen in a matching-to-sample arrangement. In Experiment 1, the ponies had to relate two similar quantities to another, paired in contrasts (1 vs. 2, 3 vs. 4 and 4 vs. 5) of the same stimulus (dot). Specific pairs of quantities (all differing by one) of up to five different geometrical symbols were displayed in Experiment 2. In each session, both quantities (more and less) were used as sample in such a way that each of the two quantities presented in one test served as positive and as negative stimulus, respectively. The three Shetland ponies were able to discriminate between the given quantities of dots by showing more than 80 % correct responses in two consecutive sessions. Only one of the ponies distinguished different shapes of geometric symbols at a level of 4 versus 5 items. The results show that all ponies were capable of visual quantity discrimination in the present matching-to-sample design, but task solving seemed more difficult when quantities were composed of heterogeneous stimuli. The present results confirm our hypothesis that the ponies based their decision on the matching concept of sameness and were not biased by a spontaneous preference for higher quantities.
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Merchant, H., Fortes, A. F., & Georgopoulos, A. P. (2004). Short-term memory effects on the representation of two-dimensional space in the rhesus monkey. Anim. Cogn., 7(3), 133–143.
Abstract: Human subjects represent the location of a point in 2D space using two independent dimensions (x-y in Euclidean or radius-angle in polar space), and encode location in memory along these dimensions using two levels of representation: a fine-grain value and a category. Here we determined whether monkeys possessed the ability to represent location with these two levels of coding. A rhesus monkey was trained to reproduce the location of a dot in a circle by pointing, after a delay period, on the location where a dot was presented. Five different delay periods (0.5-5 s) were used. The results showed that the monkey used a polar coordinate system to represent the fine-grain spatial coding, where the radius and angle of the dots were encoded independently. The variability of the spatial response and reaction time increased with longer delays. Furthermore, the animal was able to form a categorical representation of space that was delay-dependent. The responses avoided the circumference and the center of the circle, defining a categorical radial prototype around one third of the total radial length. This radial category was observed only at delay durations of 3-5 s. Finally, the monkey also formed angular categories with prototypes at the obliques of the quadrants of the circle, avoiding the horizontal and vertical axes. However, these prototypes were only observed at the 5-s delay and on dots lying on the circumference. These results indicate that monkeys may possess spatial cognitive abilities similar to humans.
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Sueur, C., & Petit, O. (2010). Signals use by leaders in Macaca tonkeana and Macaca mulatta: group-mate recruitment and behaviour monitoring. Anim. Cogn., 13(2), 239–248.
Abstract: Abstract Animals living in groups have to make consensus decisions and communicate with each other about the time, or the direction, in which to move. In some species, the process relies on the proposition of a single individual, i.e. a first individual suggests a movement and the other group members decide whether or not to join this individual. In Tonkean (Macaca tonkeana) and rhesus macaques (Macaca mulatta), it has been observed that this first individual displays specific signals at departure. In this paper, we aimed to explore the function of such behaviours, i.e. if these behaviours were recruitment signals or only cues about the motivation of the first departed individual. We carried out temporal analyses and studied the latencies of the first departed individual’s behaviours and of the joining of other group members. We also assessed whether the social style of a species in terms of dominance and kinship relationships influenced the patterns of signal emissions. We then analyzed how the first departed individual decided to make a pause or to stop it according to the identities of group members that joined the collective movement. Results showed that Tonkean macaques and rhesus macaques seemed to use back-glances to monitor the joining of other group members and pauses to recruit such individuals. This was especially the case for highly socially affiliated individuals in Tonkean macaques and kin-related individuals in rhesus macaques. Moreover, back-glances and pauses disappeared when such individuals joined the first departed individual. From these results, we suggested that such behaviour could be considered intentional. Such findings could not be highlighted without temporal analyses and accurate observations on primate groups in semi-free ranging conditions.
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Brazas, M. L., & Shimizu, T. (2002). Significance of visual cues in choice behavior in the female zebra finch (Taeniopygia guttata castanotis). Anim. Cogn., 5(2), 91–95.
Abstract: Female zebra finches show a preference for male zebra finches over heterospecific males based solely on the auditory cues of males, such as songs. The present study was designed to investigate whether females show a similar preference for male zebra finches based solely on visual cues. Using a Y-maze apparatus, social preference of female zebra finches was studied between male zebra finches and male Bengalese finches in three experiments. In experiment 1, where female zebra finches could see and hear live male zebra finches and male Bengalese finches, the females preferred to associate with the male zebra finches. In experiment 2, using a sound-attenuated experimental apparatus, subjects could see, but not hear, male zebra finches and male Bengalese finches. The subjects did not show a significant preference for associating with zebra finches. In experiment 3, as in experiment 2, females could see live male zebra finches and male Bengalese finches in the sound-attenuated chambers. However, in experiment 3, the subjects also heard prerecorded auditory cues (i.e., songs and calls) of male zebra finches, which were presented simultaneously in both arms of the maze. Although the females could not use the auditory cues to identify the location of the male zebra finches, they preferred to associate with the male zebra finches rather than the male Bengalese finches. These results suggest that visual cues alone were effective in initiating choice behaviors by females and that auditory cues facilitate such visually based choice behaviors.
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de Waal, F. B. M. (2003). Silent invasion: Imanishi's primatology and cultural bias in science. Anim. Cogn., 6(4), 293–299.
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