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| Author |
Ushitani, T.; Fujita, K.; Yamanaka, R. |
| Title |
Do pigeons (Columba livia) perceive object unity? |
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Journal Article |
| Year |
2001 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
4 |
Issue |
3 |
Pages |
153-161 |
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| Abstract |
Human infants perceive two rods moving in concert behind an occluder as one unitary rod. In four experiments we tested whether pigeons also perceive unity of objects. Pigeons were trained on a matching-to-sample task to discriminate between one unitary rod moving at a constant speed and two aligned rods moving together at the same speed. The latter stimulus was identical to the former except for a gap in the center. In experiment 1, we tested pigeons in probe trials in which a rectangle occluded the center of the sample rods, to see which comparison stimulus, the unitary rod or the aligned two rods, the subjects would match to the sample. Two of the three subjects pecked at the two rods significantly more often than at the unitary rod. In experiment 2, we trained the same pigeons to match the sample rods moving “in front of” the occluder. Pigeons persisted in matching two separate rods to the unitary rod moving in front of the occluder. In experiments 3 and 4, we used a parallelogram and an undulating shape as the occluder to alter the shape and the size of the portions above and below the occluder by the motion of the sample rods. Both subjects chose the two rods significantly more often than chance in experiment 3 and one of them did so in experiment 4. The results suggest that pigeons do not complete occluded portions even though the two elements move in concert. These negative results suggest that some alternative way of identifying objects may have evolved in pigeons. |
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Equine Behaviour @ team @ |
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3311 |
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| Author |
Hirata, S.; Matsuzawa, T. |
| Title |
Tactics to obtain a hidden food item in chimpanzee pairs (Pan troglodytes) |
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Journal Article |
| Year |
2001 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
4 |
Issue |
3 |
Pages |
285-295 |
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Five dyads of chimpanzees were tested in a competitive situation, as a pilot study to examine chimpanzees' understanding of conspecifics' knowledge. A human experimenter baited one of five containers in an outdoor enclosure. Chimpanzee A (witness) could see where the food was hidden, while chimpanzee B (witness-of-witness) could not see the baited place but could observe the chimpanzee A watching the food being hidden. Then the two were released into the enclosure. This procedure was repeated for a certain number of days along with a control condition in which neither could see the baited location. The witness-of-witness developed tactics to forestall the witness in two pairs. The witness misled the witness-of-witness by taking a route to an empty container in several cases. These episodes might represent examples of deception. Tactics and counter-tactics thus developed through the interaction between the witness and the witness-of-witness, illustrating the high social intelligence of chimpanzees. An examination of the changes in tactics suggests a possibility that the witness-of-witness understands the witness's knowledge of the location of hidden food. |
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Equine Behaviour @ team @ |
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3313 |
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Regolin, L.; Tommasi, L.; Vallortigara, G. |
| Title |
Visual perception of biological motion in newly hatched chicks as revealed by an imprinting procedure |
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Journal Article |
| Year |
2000 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
3 |
Issue |
1 |
Pages |
53-60 |
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Day-old chicks were exposed to point-light animation sequences depicting either a walking hen or a rotating cylinder. On a subsequent free-choice test (experiment 1) the chicks approached the novel stimulus, irrespective of this being the hen or the cylinder. In order to obtain equivalent local motion vectors, in experiments 2 and 3 newly hatched chicks were exposed either to a point-light animation sequence depicting a walking hen, or to a positionally scrambled walking hen (i.e. an animation in which exactly the same set of dots in motion as that employed for the walking hen was presented, but with spatially randomized starting positions). Chicks tested on day 1 (experiment 2) or on day 2 (i.e. after a period in the dark following exposure on day 1 (experiment 3)) proved able to discriminate the two animation sequences: males preferentially approached the novel stimulus, females the familiar one. These results indicate that discrimination was not based on local motion vectors, but rather on the temporally integrated motion sequence. |
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Equine Behaviour @ team @ |
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3314 |
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Kusayama, T.; Bischof, H.-J.; Watanabe, S. |
| Title |
Responses to mirror-image stimulation in jungle crows (Corvus macrorhynchos) |
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Journal Article |
| Year |
2000 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
3 |
Issue |
1 |
Pages |
61-64 |
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Four jungle crows (Corvus macrorhynchos) were exposed to a mirror placed either vertically or horizontally. The most frequently observed behaviors were pecking at the mirror and wing flapping when looking toward the mirror. These behavior patterns, which were only rarely observed when the mirror was reversed, can be interpreted as aggressive behaviors against a conspecific. The vertical mirror evoked the behaviors more often than the horizontal mirror. The present results suggest that crows perceive their mirror image as an image of a conspecific, not as their own. |
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Equine Behaviour @ team @ |
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3319 |
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Call, J.; Carpenter, M. |
| Title |
Do apes and children know what they have seen? |
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Journal Article |
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2001 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
3 |
Issue |
4 |
Pages |
207-220 |
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Chimpanzees and young children understand much about what other individuals have and have not seen. This study investigates what they understand about their own visual perception. Chimpanzees, orangutans, and 2.5-year-old children were presented with a finding game in which food or stickers were hidden in one of two or three tubes. We varied whether subjects saw the baiting of the tubes, whether subjects could see through the tubes, and whether there was a delay between baiting and presentation of the tubes to subjects. We measured not only whether subjects chose the correct tube but also, more importantly, whether they spontaneously looked into one or more of the tubes before choosing one. Most apes and children appropriately looked into the tubes before choosing one more often when they had not seen the baiting than when they had seen the baiting. In general, they used efficient search strategies more often than insufficient or excessive ones. Implications of subjects' search patterns for their understanding of seeing and knowing in the self are discussed. |
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Equine Behaviour @ team @ |
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3321 |
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Westergaard, G.C. |
| Title |
Structural analysis of tool-use by tufted capuchins (Cebus apella) and chimpanzees (Pan troglodytes) |
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Journal Article |
| Year |
1999 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
2 |
Issue |
3 |
Pages |
141-145 |
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Using Matsuzawa's hierarchical system of classification, I compared tool-use patterns of tufted capuchins (Cebus apella) to those of chimpanzees (Pan troglodytes). The results indicated that wild C. apella exhibit fewer and less complex tool-use patterns than do captive C. apella and wild and captive P. troglodytes. Although most patterns of tool-use observed among P. troglodytes occur in captive C. apella, there are some notable exceptions, including tool-use in communicative contexts and the use ¶of three-tool combinations. I conclude that C. apella are unique among monkeys in their demonstrated propensities for higher-order combinatorial behavior and are likely capable of using symbolic combinations, although not at the level of complexity that has been demonstrated in ¶P. troglodytes. |
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Equine Behaviour @ team @ |
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3324 |
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Beran, M.; Rumbaugh, D. |
| Title |
“Constructive” enumeration by chimpanzees (Pan troglodytes) on a computerized task |
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Journal Article |
| Year |
2001 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
4 |
Issue |
2 |
Pages |
81-89 |
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Two chimpanzees used a joystick to collect dots, one at a time, on a computer monitor (see video-clip in the electronic supplementary material), and then ended a trial when the number of dots collected was equal to the Arabic numeral presented for the trial. Both chimpanzees performed substantially and reliably above chance in collecting a quantity of dots equal to the target numeral, one chimpanzee for the numerals 1-7, and the second chimpanzee for the numerals 1-6. Errors that were made were seldom discrepant from the target by more than one dot quantity, and the perceptual process subitization was ruled out as an explanation for the performance. Additionally, analyses of trial duration data indicated that the chimpanzees were responding based on the numerosity of the constructed set rather than on the basis of temporal cues. The chimpanzees' decreasing performance with successively larger target numerals, however, appeared to be based on a continuous representation of magnitude rather than a discrete representation of number. Therefore, chimpanzee counting in this type of experimental task may be a process that represents magnitudes with scalar variability in that the memory for magnitudes associated with each numeral is imperfect and the variability of responses increases as a function of the numeral's value. |
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Equine Behaviour @ team @ |
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3329 |
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Wiltschko, W.; Balda, R.P.; Jahnel, M.; Wiltschko, R. |
| Title |
Sun compass orientation in seed-caching corvids: its role in spatial memory |
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Journal Article |
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1999 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
2 |
Issue |
4 |
Pages |
215-221 |
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The role of sun compass orientation in spatial memory of Clark's nutcrackers, Nucifraga columbiana, and pinyon jays, Gymnorhinus cyanocephalus, was studied in a series of cache recovery experiments. Birds were tested in an octagonal outdoor aviary with sand-filled cups inserted in the floor. For caching, only 12 such cups in a 90° sector were available, while for recovery 4-7 days later all 48 cups in the entire aviary were open. In control tests, the birds concentrated their search activity in the sector where they had cached. When their internal clock was shifted 6 h between caching and recovery, pinyon jays shifted their search activity to the 90° adjacent sector, as predicted if the sun compass was used. Clark's nutcrackers did not respond to the first clock-shift; however, they, too, shifted their search activity after a second clock-shift back to normal. This suggests that the sun compass is a component of spatial memory in both species. Clark's nutcrackers, however, seem to rely on their sun compass to a lesser degree than pinyon jays or the previously studied scrub jays. A comparison of the findings indicates that the role of the sun in spatial memory might reflect differences in habitat and ecology of the three corvid species. |
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Equine Behaviour @ team @ |
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3335 |
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Waite, T.A.; Field, K.L. |
| Title |
Erroneous choice and foregone gains in hoarding gray jays (Perisoreus canadensis) |
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Journal Article |
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2000 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
3 |
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3 |
Pages |
127-134 |
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Under the conventional assumption that natural selection favors choice behavior that maximizes some fitness-related currency, a forager making repeated binary choices should consistently choose the more valuable option. Under the alternative assumption that natural selection favors choice behavior that minimizes costly errors, erroneous choice is not only expected but is expected to be common when the cost of errors is low. This cost depends on the potential rate of return: the higher this rate, the smaller the cost of choosing the less valuable option. When this rate is very high, a forager may err frequently and yet forego no appreciable fitness gain. Errors should thus be more common when interruptions to foraging are shorter. Our experimental results supported this prediction: gray jays chose the less valuable option more frequently when subjected to shorter interruptions (experimentally imposed delays to access to food rewards). This tendency is consistent with the idea that an adaptive decision-making process may routinely produce errors, not because errors are in some way adaptive but because their fitness cost is minimal, particularly when delays are short. From a proximate perspective, this tendency to commit errors more frequently following shorter delays may be due to constraints on the jays' information-processing capacity. In general, choice behavior should be viewed as the joint byproduct of adaptive decision making and cognitive constraints. |
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Equine Behaviour @ team @ |
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3339 |
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| Author |
Nakajima, S. |
| Title |
Failure of hierarchical conditional rule learning in the pigeon (Columba livia) |
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Journal Article |
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2001 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
3 |
Issue |
4 |
Pages |
221-226 |
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Pigeons were trained with a conditional discrimination task in three-key operant chambers. Choosing either the left or right key was followed by food according to combinations of three preceding events: (a) a houselight illumination condition (dark or light), (b) presence or absence of green flashes on the three keys, (c) a color (amber or blue) of the center sample key. With these 2ǶǶ event combinations, eight types of correct trials were prepared: (1) darkMno flashMamberMLEFT, (2) darkMno flashMblueMRIGHT, (3) darkMflashMamberMRIGHT, (4) darkMflashMblueMLEFT, (5) lightMno flashMamberMRIGHT, (6) lightMno flashMblueMLEFT, (7) lightMflashMamberMLEFT, and (8) lightMflashMblueMRIGHT. Seven of these eight types were used for training of a given bird, and then the remaining trial type was presented as the test. If the birds had learned the conditional structure of the events (the hierarchical switching rule), they would have responded correctly to the test type. However, they chose the opposite side key, suggesting that they had learned cue configuration or multiple rules to solve the task. |
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Equine Behaviour @ team @ |
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3341 |
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