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Author (up) Fagot, J.; Tomonaga, M.
Title Effects of element separation on perceptual grouping by humans (Homo sapiens) and chimpanzees (Pan troglodytes): perception of Kanizsa illusory figures Type Journal Article
Year 2001 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 4 Issue 3 Pages 171-177
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Abstract The processing of Kanizsa-square illusory figures was studied in two experiments with four humans and two chimpanzees. Subjects of the two species were initially trained to select a Kanizsa-square illusory figure presented in a computerized two-alternative forced choice task. After training, adding narrow closing segments to the pacman inducers that composed the Kanisza illusory figures lowered performance in both chimpanzees and humans, suggesting that the discrimination could be controlled by the perception of illusory forms. A second experiment assessed transfer of performance with five sets of figures in which the size of the inducers and their separation were manipulated. Only for chimpanzees was performance directly controlled by separation, suggesting that chimpanzees are more sensitive than humans to the separation between visual elements.
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Call Number Equine Behaviour @ team @ Serial 3172
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Author (up) Imura, T.; Tomonaga, M.
Title Perception of depth from shading in infant chimpanzees ( Pan troglodytes) Type Journal Article
Year 2003 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 6 Issue 4 Pages 253-258
Keywords Age Factors; Animals; Contrast Sensitivity/*physiology; Depth Perception/*physiology; Discrimination Learning/*physiology; Female; Male; Pan troglodytes/growth & development/*physiology/*psychology; Pattern Recognition, Visual/physiology
Abstract We investigated the ability to perceive depth from shading, one of the pictorial depth cues, in three chimpanzee infants aged 4-10 months old, using a preferential reaching task commonly used to study pictorial depth perception in human infants. The chimpanzee infants reached significantly more to three-dimensional toys than to pictures thereof and more to the three-dimensional convex than to the concave. Furthermore, two of the three infants reached significantly more to the photographic convex than to the photographic concave. These infants also looked longer at the photographic convex than the concave. Our results suggest that chimpanzees perceive, at least as early as the latter half of the first year of life, pictorial depth defined by shading information. Photographic convexes contain richer information about pictorial depth (e.g., attached shadow, cast shadow, highlighted area, and global difference in brightness) than simple computer-graphic graded patterns. These cues together might facilitate the infants' perception of depth from shading.
Address Graduate School of Humanities, Kwansei Gakuin University, Uegahara, Nishinomiya, Hyogo 662-8501, Japan
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ISSN 1435-9448 ISBN Medium
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Notes PMID:14610661 Approved no
Call Number Equine Behaviour @ team @ Serial 2550
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Author (up) Matsuzawa, T.; Tomonaga, M.
Title For a rise of comparative cognitive science Type Journal Article
Year 2001 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 4 Issue 3 Pages 133-135
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Call Number Equine Behaviour @ team @ Serial 3299
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Author (up) Murai, C.; Tomonaga, M.; Kamegai, K.; Terazawa, N.; Yamaguchi, M.K.
Title Do infant Japanese macaques ( Macaca fuscata) categorize objects without specific training? Type Journal Article
Year 2004 Publication Primates Abbreviated Journal Primates
Volume 45 Issue 1 Pages 1-6
Keywords Analysis of Variance; Animals; *Cognition; *Concept Formation; *Generalization, Stimulus; Japan; Macaca/*psychology; Male
Abstract In the present study, we examined whether infant Japanese macaques categorize objects without any training, using a similar technique also used with human infants (the paired-preference method). During the familiarization phase, subjects were presented twice with two pairs of different objects from one global-level category. During the test phase, they were presented twice with a pair consisting of a novel familiar-category object and a novel global-level category object. The subjects were tested with three global-level categories (animal, furniture, and vehicle). It was found that they showed significant novelty preferences as a whole, indicating that they processed similarities between familiarization objects and novel familiar-category objects. These results suggest that subjects responded distinctively to objects without training, indicating the possibility that infant macaques possess the capacity for categorization.
Address Department of Psychology, Graduate School of Letters, Kyoto University, Sakyo, Kyoto 606-8501, Japan. cmurai@bun.kyoto-u.ac.jp
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ISSN 0032-8332 ISBN Medium
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Notes PMID:14505179 Approved no
Call Number Equine Behaviour @ team @ Serial 2813
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Author (up) Okamoto, S.; Tomonaga, M.; Ishii, K.; Kawai, N.; Tanaka, M.; Matsuzawa, T.
Title An infant chimpanzee (Pan troglodytes) follows human gaze Type Journal Article
Year 2002 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 5 Issue 2 Pages 107-114
Keywords Animals; Animals, Newborn/*psychology; Attention; *Cognition; Conditioning, Operant; Male; Pan troglodytes/*psychology; *Social Behavior; *Visual Perception
Abstract The ability of non-human primates to follow the gaze of other individuals has recently received much attention in comparative cognition. The aim of the present study was to investigate the emergence of this ability in a chimpanzee infant. The infant was trained to look at one of two objects, which an experimenter indicated by one of four different cue conditions: (1) tapping on the target object with a finger; (2) pointing to the target object with a finger; (3) gazing at the target object with head orientation; or (4) glancing at the target object without head orientation. The subject was given food rewards independently of its responses under the first three conditions, so that its responses to the objects were not influenced by the rewards. The glancing condition was tested occasionally, without any reinforcement. By the age of 13 months, the subject showed reliable following responses to the object that was indicated by the various cues, including glancing alone. Furthermore, additional tests clearly showed that the subject's performance was controlled by the “social” properties of the experimenter-given cues but not by the non-social, local-enhancing peripheral properties.
Address Department of Psychology, School of Letters, Nagoya University, Nagoya, Aichi 464-8601, Japan. sokamot@yahoo.co.jp
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ISSN 1435-9448 ISBN Medium
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Notes PMID:12150035 Approved no
Call Number Equine Behaviour @ team @ Serial 2609
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Author (up) Tanaka, M.; Tomonaga, M.; Matsuzawa, T.
Title Finger drawing by infant chimpanzees ( Pan troglodytes) Type Journal Article
Year 2003 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 6 Issue 4 Pages 245-251
Keywords Animals; *Art; Female; *Fingers; *Gestures; Male; Motor Skills/*physiology; Pan troglodytes/*physiology/*psychology
Abstract We introduced a new technique to investigate the development of scribbling in very young infants. We tested three infant chimpanzees to compare the developmental processes of scribbling between humans and chimpanzees. While human infants start to scribble on paper at around the age of 18 months, our 13- to 23-month-old infant chimpanzees had never been observed scribbling prior to this study. We used a notebook computer with a touch-sensitive screen. This apparatus was able to record the location of the subjects' touches on the screen. Each touch generated a fingertip-sized dot at the corresponding on-screen location. During spontaneous interactions with this apparatus, all three infants and two mother chimpanzees left scribbles with their fingers on the screen. The scribbles contained not only simple dots or short lines, but also curves and hook-like lines or loops, most of which were observed in the instrumental drawings of adult chimpanzees. The results suggest that perceptual-motor control for finger drawing develops in infant chimpanzees. Two of the infants performed their first scribble with a marker on paper at the age of 20-23 months. Just prior to this, they showed a rapid increase in combinatory manipulation of objects. These findings suggest that the development of combinatory manipulation of objects as well as that of perceptual-motor control may be necessary for the emergence of instrumental drawing on paper.
Address Section of Language and Intelligence, Primate Research Institute, Kyoto University, 41 Kanrin, 484-8506 Inuyama, Aichi, Japan. mtanaka@pri.kyoto-u.ac.jp
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ISSN 1435-9448 ISBN Medium
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Notes PMID:14605946 Approved no
Call Number Equine Behaviour @ team @ Serial 2551
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Author (up) Tomonaga, M.
Title Relative numerosity discrimination by chimpanzees (Pan troglodytes): evidence for approximate numerical representations Type Journal Article
Year 2007 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume Issue Pages
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Abstract Two adult chimpanzees were trained on a relative “numerosity” discrimination task. In each trial, two arrays containing different numbers of red dots were presented on a CRT monitor. The subjects were required to choose the array containing the larger number of dots. In Experiment 1, using numerosities between 1 and 8, 28 different pairs were presented repeatedly, and accuracy scores were analyzed to explore which cues the chimpanzee subjects utilized to perform the task. Multiple regression analyses revealed that the subjects' performance was (1) not simply controlled by the “numerical” difference between arrays, but that it was (2) best described by Fechner's Law-that is accuracy increased linearly with the logarithmic value of the numerical difference between arrays divided by the number in the larger of the two arrays. This relationship was maintained when using much larger numerosities (Experiment 3). In Experiment 2, the chimpanzees were tested on the effects of total area and density by manipulating dot size and presentation area. The results revealed that these factors clearly affected the subjects' performance but that they could not alone explain the results, suggesting that the chimpanzees did use relative numerosity difference as a discriminative cue.
Address Section of Language and Intelligence, Primate Research Institute, Kyoto University, Inuyama, Aichi, 484-8506, Japan, tomonaga@pri.kyoto-u.ac.jp
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ISSN 1435-9448 ISBN Medium
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Notes PMID:17443355 Approved no
Call Number Equine Behaviour @ team @ Serial 2402
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Author (up) Tomonaga, M.; Matsuzawa, T.
Title Sequential responding to arabic numerals with wild cards by the chimpanzee (Pan troglodytes) Type Journal Article
Year 2000 Publication Animal Cognition Abbreviated Journal Anim. Cogn.
Volume 3 Issue 1 Pages 1-11
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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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Call Number Equine Behaviour @ team @ Serial 3373
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