|
|
Sovrano, V. A., Bisazza, A., & Vallortigara, G. (2007). How fish do geometry in large and in small spaces. Anim. Cogn., 10(1), 47–54.
Abstract: It has been shown that children and non-human animals seem to integrate geometric and featural information to different extents in order to reorient themselves in environments of different spatial scales. We trained fish (redtail splitfins, Xenotoca eiseni) to reorient to find a corner in a rectangular tank with a distinctive featural cue (a blue wall). Then we tested fish after displacement of the feature on another adjacent wall. In the large enclosure, fish chose the two corners with the feature, and also tended to choose among them the one that maintained the correct arrangement of the featural cue with respect to geometric sense (i.e. left-right position). In contrast, in the small enclosure, fish chose both the two corners with the features and the corner, without any feature, that maintained the correct metric arrangement of the walls with respect to geometric sense. Possible reasons for species differences in the use of geometric and non-geometric information are discussed.
|
|
|
|
Sovrano, V., & Bisazza, A. (2008). Recognition of partly occluded objects by fish. Anim. Cogn., 11(1), 1435–9448.
Abstract: Abstract The ability to visually complete partly occluded objects (so-called `“amodal completion”) has been documented in mammals and birds. Here, we report the first evidence of such a perceptual ability in a fish species. Fish (Xenotoca eiseni) were trained to discriminate between a complete and an amputated disk. Thereafter, the fish performed test trials in which hexagonal polygons were either exactly juxtaposed or only placed close to the missing sectors of the disk in order to produce or not produce the impression (to a human observer) of an occlusion of the missing sectors of the disk by the polygon. In another experiment, fish were first trained to discriminate between hexagonal polygons that were either exactly juxtaposed or only placed close to the missing sectors of a disk, and then tested for choice between a complete and an amputated disk. In both experiments, fish behaved as if they were experiencing visual completion of the partly occluded stimuli. These findings suggest that the ability to visually complete partly occluded objects may be widespread among vertebrates, possibly inherited in mammals, birds and fish from early vertebrate ancestors.
|
|
|
|
Sousa, C., Okamoto, S., & Matsuzawa, T. (2003). Behavioural development in a matching-to-sample task and token use by an infant chimpanzee reared by his mother. Anim. Cogn., 6(4), 259–267.
Abstract: We investigated the behavioural and cognitive development of a captive male infant chimpanzee, Ayumu, raised by his mother, Ai. Here we report Ayumu's achievements up to the age of 2 years and 3 months, in the context of complex computer-controlled tasks. From soon after birth, Ayumu had been present during an experiment performed by his mother. The task consisted of two phases, a matching-to-sample task in which she received token rewards, and the insertion of these tokens into a vending machine to obtain food rewards. Ayumu himself received no reward or encouragement from humans for any of the actions he exhibited during the experiment. At the age of 9 months and 3 weeks, Ayumu performed his first matching-to-sample trial. At around 1 year and 3 months, he began to perform them consistently. Also during this period, he frequently stole food rewards from his mother. At 2 years and 3 months, Ayumu succeeded for the first time in inserting a token into the vending machine. Once he had succeeded in using a token, he performed both phases of the task in sequence 20 times consecutively. The infant's behaviour was not shaped by food rewards but by a strong motivation to copy his mother's behaviour. Our observations of Ayumu thus mirror the learning processes shown by wild chimpanzees.
|
|
|
|
Sousa, C., & Matsuzawa, T. (2001). The use of tokens as rewards and tools by chimpanzees (Pan troglodytes). Anim. Cogn., 4(3), 213–221.
Abstract: This paper explores the effectiveness of token rewards in maintaining chimpanzees ( Pan troglodytes) in working at intellectually costly tasks, and studies the “saving” behavior of the subjects, investigating the factors that can condition it. Two experiments were run. Tokens were introduced as rewards in a matching-to-sample task and used as exchange tools for food by three adult female chimpanzees. Subjects' performances were maintained at constant high levels of accuracy, suggesting that the tokens were almost equivalent to direct food rewards. The results also showed the emergence of saving behavior. The subjects spontaneously saved the tokens during the matching-to-sample task before exchanging them for food. The chimpanzees also learned a new symbolic discrimination task, with tokens as the reward. During this learning process a rarely reported phenomenon emerged: one of the subjects showed symmetry, a form of stimulus equivalence.
|
|
|
|
Sommer, V., Lowe, A., & Dietrich, T. (2016). Not eating like a pig: European wild boar wash their food. Anim. Cogn., 19(1), 245–249.
Abstract: Carrying food to water and either dunking or manipulating it before consumption has been observed in various taxa including birds, racoons and primates. Some animals seem to be simply moistening their food. However, true washing aims to remove unpleasant surface substrates such as grit and sand and requires a distinction between items that do and do not need cleaning as well as deliberate transportation of food to a water source. We provide the first evidence for food washing in suids, based on an incidental observation with follow-up experiments on European wild boar (Sus scrofa) kept at Basel Zoo, Switzerland. Here, all adult pigs and some juveniles of a newly formed group carried apple halves soiled with sand to the edge of a creek running through their enclosure where they put the fruits in the water and pushed them to and fro with their snouts before eating. Clean apple halves were never washed. This indicates that pigs can discriminate between soiled and unsoiled foods and that they are able to delay gratification for long enough to transport and wash the items. However, we were unable to ascertain to which degree individual and/or social learning brought this behaviour about.
|
|
|
|
Soler, M., & Soler, J. J. (1999). Innate versus learned recognition of conspecifics in great spotted cuckoos Clamator glandarius. Anim. Cogn., 2(2), 97–102.
Abstract: When birds raised by another species become adults, they (if they are non-brood-parasitic species) usually attempt to mate with birds of their foster species rather than with birds of their own species, a phenomenon called sexual imprinting. Avian brood parasites lay their eggs in nests of other species (the hosts) that rear the young, but the problem of sexual imprinting among brood parasites has generally been neglected, and brood parasites have been considered as an exception among birds. Here, we show, with data from field observations and field experiments, firstly, that adult great spotted cuckoos Clamator glandarius sometimes maintain contact with both older nestling and fledgling cuckoos. Adult cuckoos visited parasitized nests during the last days of the nestling period (5 observations) and, when parasitic chicks left the nest, adult cuckoos maintained contact with the young (14 observations). Adults and fledgling cuckoos communicated vocally (5 observations), and an adult great spotted cuckoo even fed a parasite fledgling in two cases. Secondly, when experimentally cross-fostered in nests of magpie Pica pica hosts outside the parasite breeding range (thus avoiding visual and acoustic communication with adult cuckoos), young cuckoos did not learn to recognize their own species when only one cuckoo chick was introduced per nest, but they learnt to recognize conspecifics when two cuckoos were reared together. This means that young great spotted cuckoos apparently must learn to recognize conspecifics, that is, recognition is not innate. Social interactions between adult brood parasites and young have also been reported in other brood parasites; thus, brood parasites are probably not an exception to the general phenomenon of imprinting, and young brood parasites may need to be imprinted on conspecifics, although more studies on other brood parasite species are needed to confirm this.
|
|
|
|
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.
|
|
|
|
Smith, B., & Litchfield, C. (2010). Dingoes (Canis dingo) can use human social cues to locate hidden food. Anim. Cogn., 13(2), 367–376.
Abstract: Abstract There is contention concerning the role that domestication plays in the responsiveness of canids to human social cues, with most studies investigating abilities of recognized domestic dog breeds or wolves. Valuable insight regarding the evolution of social communication with humans might be gained by investigating Australian dingoes, which have an early history of domestication, but have been free-ranging in Australia for approximately 3500–5000 years. Seven ‘pure’ dingoes were tested outdoors by a familiar experimenter using the object-choice paradigm to determine whether they could follow nine human communicative gestures previously tested with domestic dogs and captive wolves. Dingoes passed all cues significantly above control, including the “benchmark” momentary distal pointing, with the exception of gaze only, gaze and point, and pointing from the incorrect location. Dingo performance appears to lie somewhere between wolves and dogs, which suggests that domestication may have played a role in their ability to comprehend human gestures.
|
|
|
|
Slobodchikoff, C., Paseka, A., & Verdolin, J. (2009). Prairie dog alarm calls encode labels about predator colors. Anim. Cogn., 12(3), 435–439.
Abstract: Some animals have the cognitive capacity to differentiate between different species of predators and generate different alarm calls in response. However, the presence of any addition information that might be encoded into alarm calls has been largely unexplored. In the present study, three similar-sized human females walked through a Gunnison’s prairie dog ( Cynomys gunnisoni ) colony wearing each of three different-colored shirts: blue, green, and yellow. We recorded the alarm calls and used discriminant function analysis to assess whether the calls for the different-colored shirts were significantly different. The results showed that the alarm calls for the blue and the yellow shirts were significantly different, but the green shirt calls were not significantly different from the calls for the yellow shirt. The colors that were detected, with corresponding encoding into alarm calls, reflect the visual perceptual abilities of the prairie dogs. This study suggests that prairie dogs are able to incorporate labels about the individual characteristics of predators into their alarm calls, and that the complexity of information contained in animal alarm calls may be greater than has been previously believed.
|
|
|
|
Shuster, G., & Sherman, P. W. (1998). Tool use by naked mole-rats. Anim. Cogn., 1(1), 71–74.
Abstract: Naked mole-rats (Heterocephalus glaber, Rodentia: Bathyergidae) excavate extensive subterranean burrows with their procumbent incisors. Captive individuals often place a wood shaving or tuber husk behind their incisor teeth and in front of their lips and molar teeth while gnawing on substrates that yield fine particulate debris. This oral barrier may prevent choking or aspiration of foreign material. Consistent use of tools has rarely been reported in rodents.
|
|
