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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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Benhamou, S. (1998). Place navigation in mammals: a configuration-based model. Anim. Cogn., 1(1), 55–63.
Abstract: Recent water maze experiments suggest that rats performing place navigation primarily use the geometric information provided by a set of landmarks, and neglect the featural information provided by the identities of the landmarks. Here, I develop a model that explains how an animal may perform place navigation by relying only on geometric information. The core of the model is the representation of places as panoramas defined by circular bar-codes embodying the relative bearings and apparent sizes of the landmarks, irrespective of their identities. There are two stages in the model. During the first stage, the animal freely explores its environment in order to acquire spatial information at the local level. During the second stage, the animal uses the information previously memorized to perform place navigation towards the goal it intends to reach. The possible role of two brain areas in place navigation is discussed within this framework. Beyond their primary role in landmark-based representations of places, hippocampal place cells may be involved in computing the current distances to the landmarks. Beyond their primary role in landmark-based representations of headings, post-subicular head-direction cells may be involved in computing the “compass bearings” of the landmarks.
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Vallortigara, G., Regolin, L., Rigoni, M., & Zanforlin, M. (1998). Delayed search for a concealed imprinted object in the domestic chick. Anim. Cogn., 1(1), 17–24.
Abstract: Five-day-old chicks were accustomed to follow an imprinted object (a small red ball with which they had been reared) that was moving slowly in a large arena, until it disappeared behind an opaque screen. In experiments, each chick was initially confined in a transparent cage, from where it could see and track the ball while it moved towards, and then beyond, one of two screens. The screens could be either identical or differ in colour and pattern. Either immediately after the disappearance of the ball, or with a certain delay, the chick was released and allowed to search for its imprinted object behind either screen. The results showed that chicks took into account the directional cue provided by the ball movement and its concealment, up to a delay period of about 180 s, independently of the perceptual characteristics of the two screens. If an opaque partition was positioned in front of the transparent cage immediately after the ball had disappeared, so that, throughout the delay, neither the goal-object nor the two screens were visible, chicks were still capable of remembering and choosing the correct screen, though over a much shorter period of about 60 s. The results suggest that, at least in this precocial bird species, very young chicks can maintain some form of representation of the location where a social partner was last seen, and are also capable of continuously updating this representation so as to take into account successive displacements of the goal-object.
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Vick, S. - J., Bovet, D., & Anderson, J. (2001). Gaze discrimination learning in olive baboons (Papio anubis). Anim. Cogn., 4(1), 1–10.
Abstract: The ability to discriminate between pairs of photographs according to the portrayed model's visual attention status was examined in four olive baboons. Two baboons successfully managed to solve the problem, even when attention was demonstrated by eye direction alone. A third showed an ability to discriminate head direction but not eye direction. In order to investigate further their ability to discriminate attention, the two successful baboons and two naïve baboons were presented with a simple object-choice task accompanied by experimenter-given cues. There was no evidence of transfer from the photographic stimuli to a real model; only one baboon showed signs of using the experimenter's attention to chose between two objects, and only after over 300 trials. These results could suggest that the baboons used simple physical cues rather than a concept of attention to solve the picture discrimination but alternative explanations are also discussed.
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López, J., Gómez, Y., Rodríguez, F., Broglio, C., Vargas, J., & Salas, C. (2001). Spatial learning in turtles. Anim. Cogn., 4(1), 49–59.
Abstract: Turtles (Pseudemys scripta) were trained in place, cue and control open-field procedures. The turtles trained in both the place and the cue procedures were able to learn their respective tasks with accuracy. Subsequent probe tests revealed that the turtles trained in the place task relied on the information provided by the extramaze cues to locate the goal. However, for these animals, no single cue was essential for performance, as accurate navigation to the goal was still possible when subsets of extramaze cues were eliminated. Furthermore, the turtles trained in the place task were able to navigate accurately to the goal place from new start locations. These results suggest that the turtles trained in the place task used map-like, relational strategies, by encoding the simultaneous spatial relationships between the goal and the extramaze cues in an allocentric frame of reference. In contrast, the turtles trained in the cue procedure used guidance strategies, i.e. approaching the individual intramaze cue associated to the goal as it were a beacon and largely ignoring the extramaze cues. Thus, the results of this experiment suggest that turtles are able to employ spatial strategies that closely parallel those described in mammals and birds.
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Theall, L. A., & Povinelli, D. J. (1999). Do chimpanzees tailor their gestural signals to fit the attentional states of others? Anim. Cogn., 2(4), 207–214.
Abstract: The use of vocalizations and tactile gestures by seven juvenile chimpanzees was experimentally investigated. The subjects interacted with an experimenter who typically handed them food rewards. In some trials, however, the experimenter waited 20 s before doing so. In these trials the experimenter's eyes were either open or closed, or the experimenter was either looking away from the subject or looking directly at him/her inquisitively with head movements. Although the chimpanzees produced at least one of the non-visual gestures mentioned (touching/tapping the experimenter or vocalizing) in 72% of all experimental trials, these actions and vocalizations were deployed without regard to the attentional state of their potential recipient, despite evidence that the subjects noticed the postures that defined the experimenter's attentional state. The results are discussed in the context of the distinction between the evolution of an understanding of seeing/attention as an internal mental state versus an understanding of behavioral postures alone.
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Spinozzi, G., Natale, F., Langer, J., & Brakke, K. E. (1999). Spontaneous class grouping behavior by bonobos (Pan paniscus) and common chimpanzees (P. troglodytes). Anim. Cogn., 2(3), 157–170.
Abstract: Two experiments investigated spontaneous class grouping behavior by human-enculturated and language-reared bonobos (Pan paniscus) and common chimpanzees (P. troglodytes). In experiment 1, three chimpanzees ranging in age from 6 to 18 years were presented with six objects. The objects embodied three conditions: additive, multiplicative and disjoint classes. All chimpanzees spontaneously produced single- and two-category classifying. In experiment 2, six chimpanzees ranging in age from 6 to 21 years were presented with 12 objects in the same class conditions. Chimpanzees mainly produced single-category classifying. Their two-category classifying was more rudimentary than that found in experiment 1. Chimpanzees did not produce any three-category classifying which would be necessary to construct the hierarchies that humans begin to construct during early childhood.
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Byrne, R. W., Corp, N., & Byrne, J. M. (2001). Manual dexterity in the gorilla: bimanual and digit role differentiation in a natural task. Anim. Cogn., 4(3), 347–361.
Abstract: The manipulative actions of mountain gorillas Gorilla g. beringei were examined in the context of foraging on hard-to-process plant foods in the field, in particular those used in tackling thistle Carduus nyassanus. A repertoire of 72 functionally distinct manipulative actions was recorded. Many of these actions were used in several variants of grip, finger(s) and movement path, both by different individuals and by the same individual at different times. The repertoire appears somewhat greater than that observed in comparable studies of monkeys, but a far more striking difference is found in the use of differentiated actions in concert. Mountain gorillas routinely and frequently deal with problems that involve: (1) bimanual role differentiation, with the two hands taking different roles but synchronized in time and space, and (2) digit role differentiation, with independent control of parts of the same hand used for separate purposes at the same time. The independent control that allows these abilities, so crucial to human manual constructional ability, is apparently general in African great apes. Role differentiation, between and within the hand, is evidently a primitive characteristic in the human arsenal of skills.
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Werner, C. W., & Rehkämper, G. (1999). Discrimination of multidimensional geometrical figures by chickens: categorization and pattern-learning. Anim. Cogn., 2(1), 27–40.
Abstract: Japanese bantam hens were trained to discriminate between geometrical figures varying along four integral dimensions. Only one dimension predicted food: selections of sharp-cornered figures were reinforced, while selections of rounded figures were not. In experiment 1, hens were subsequently trained to discriminate between nine figure pairs in a simultaneous discrimination task. Because single pairs contained multiple redundant cues, whereas the relevant dimension was obvious only across stimulus pairs, the results revealed effects of both generalization and reversal learning. Accordingly, learning speed was enhanced for later discriminations. Experiment 2 tested the hens“ transfer performance to unknown pairs, following experience of 9 or 18 figure pairs. Four of seven hens showed reliable transfer after experience with 9 figures, but only three showed transfer after experience with 18 figures, indicating lower transfer with higher number of stimulus pairs learned. In experiment 3, hens were trained to discriminate 27 figure pairs. Discrimination ratios further decreased and the groups of pairs differed significantly in their ratios of discrimination. Individual hens” pecking behaviour was analysed in relation to each dimension of single figures and in relation to relative differences in the levels of dimensions between paired figures. Hens were shown to be oriented towards irrelevant information and more towards relational and configurational than elemental and dimensional aspects. The results are discussed in the biological context of individual recognition in chickens" dominance hierarchies, in which we suppose that chickens identify individual flock mates by representation of their visual pattern rather than by single characteristics.
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Johnson-Pynn, J., & Fragaszy, D. M. (2001). Do apes and monkeys rely upon conceptual reversibility? Anim. Cogn., 4(3), 315–324.
Abstract: The ability to seriate nesting cups as a sensorimotor task has posed interesting questions for cognitive scientists. Greenfield et al. [(1972) Cognit Psychol 3:291–310] found parallels between children's combinatorial activity with nesting cups and patterns of phonological and grammatical constructions. The parallels suggested the possibility of a neurally based developmental homology between language and instrumental action [Greenfield (1991) Behav Brain Sci 14:531–595]. Children who predominantly used subassembly, a hierarchical method of combining cups, succeeded at seriating nesting cups more often than those who did not. Greenfield and others [e.g., Piaget and Inhelder (1969) The psychology of the child. Basic Books, New York; DeLoache et al. (1985) Child Dev 56:928–939] argued that success in seriation reflects the child's growing recognition of a reversible relationship: a particular element in a series is conceived of as being smaller than the previous element and larger than the subsequent element. But is a concept of reversibility or a hierarchical form of object manipulation necessary to seriate cups? In this article, we review studies with very young children and nonhuman primates to determine how individuals that do not evidence conceptual reversibility manage the seriation task. We argue that the development of skill in seriation is experientially, rather than conceptually, driven and that it may be unnecessary to link seriation with cognitive conceptions of reversibility or linguistic capacities. Rather, in ordering a set of objects by size, perceptual-motor learning may enable contemplative refinement.
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