| Home | << 1 2 3 4 5 >> |
|
Call, J., Hare, B. A., & Tomasello, M. (1998). Chimpanzee gaze following in an object-choice task. Anim. Cogn., 1(2), 89–99.
Abstract: Many primate species reliably track and follow the visual gaze of conspecifics and humans, even to locations above and behind the subject. However, it is not clear whether primates follow a human's gaze to find hidden food under one of two containers in an object-choice task. In a series of experiments six adult female chimpanzees followed a human's gaze (head and eye direction) to a distal location in space above and behind them, and checked back to the human's face when they did not find anything interesting or unusual. This study also assessed whether these same subjects would also use the human's gaze in an object-choice task with three types of occluders: barriers, tubes, and bowls. Barriers and tubes permitted the experimenter to see their contents (i.e., food) whereas bowls did not. Chimpanzees used the human's gaze direction to choose the tube or barrier containing food but they did not use the human's gaze to decide between bowls. Our findings allowed us to discard both simple orientation and understanding seeing-knowing in others as the explanations for gaze following in chimpanzees. However, they did not allow us to conclusively choose between orientation combined with foraging tendencies and understanding seeing in others. One interesting possibility raised by these results is that studies in which the human cannot see the reward at the time of subject choice may potentially be underestimating chimpanzees' social knowledge.
|
|
Vlamings, P. H. J. M., Uher, J., & Call, J. (2006). How the great apes (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) perform on the reversed contingency task: the effects of food quantity and food visibility. J Exp Psychol Anim Behav Process, 32(1), 60–70.
Abstract: S. T. Boysen and G. G. Berntson (1995) found that chimpanzees performed poorly on a reversed contingency task in which they had to point to the smaller of 2 food quantities to acquire the larger quantity. The authors compared the performance of 4 great ape species (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) on the reversed contingency task while manipulating food quantity (0-4 or 1-4) and food visibility (visible pairs or covered pairs). Results showed no systematic species differences but large individual differences. Some individuals of each species were able to solve the reversed contingency task. Both quantity and visibility of the food items had a significant effect on performance. Subjects performed better when the disparity between quantities was smaller and the quantities were not directly visible.
|
|
Brauer, J., Kaminski, J., Riedel, J., Call, J., & Tomasello, M. (2006). Making inferences about the location of hidden food: social dog, causal ape. J Comp Psychol, 120(1), 38–47.
Abstract: Domestic dogs (Canis familiaris) and great apes from the genus Pan were tested on a series of object choice tasks. In each task, the location of hidden food was indicated for subjects by some kind of communicative, behavioral, or physical cue. On the basis of differences in the ecologies of these 2 genera, as well as on previous research, the authors hypothesized that dogs should be especially skillful in using human communicative cues such as the pointing gesture, whereas apes should be especially skillful in using physical, causal cues such as food in a cup making noise when it is shaken. The overall pattern of performance by the 2 genera strongly supported this social-dog, causal-ape hypothesis. This result is discussed in terms of apes' adaptations for complex, extractive foraging and dogs' adaptations, during the domestication process, for cooperative communication with humans.
Keywords: Animals; Communication; Cues; Dogs; Exploratory Behavior; *Feeding Behavior; Female; *Food; Male; Pan paniscus; Pan troglodytes; *Visual Perception
|
|
Riedel, J., Buttelmann, D., Call, J., & Tomasello, M. (2006). Domestic dogs (Canis familiaris) use a physical marker to locate hidden food. Anim. Cogn., 9(1), 27–35.
Abstract: Dogs can use the placement of an arbitrary marker to locate hidden food in an object-choice situation. We tested domestic dogs (Canis familiaris) in three studies aimed at pinning down the relative contributions of the human's hand and the marker itself. We baited one of two cups (outside of the dogs' view) and gave the dog a communicative cue to find the food. Study 1 systematically varied dogs' perceptual access to the marker placing event, so that dogs saw either the whole human, the hand only, the marker only, or nothing. Follow-up trials investigated the effect of removing the marker before the dog's choice. Dogs used the marker as a communicative cue even when it had been removed prior to the dog's choice and attached more importance to this cue than to the hand that placed it although the presence of the hand boosted performance when it appeared together with the marker. Study 2 directly contrasted the importance of the hand and the marker and revealed that the effect of the marker diminished if it had been associated with both cups. In contrast touching both cups with the hand had no effect on performance. Study 3 investigated whether the means of marker placement (intentional or accidental) had an effect on dogs' choices. Results showed that dogs did not differentiate intentional and accidental placing of the marker. These results suggest that dogs use the marker as a genuine communicative cue quite independently from the experimenter's actions.
|
|
Call, J., Agnetta, B., & Tomasello, M. (2000). Cues that chimpanzees do and do not use to find hidden objects. Anim. Cogn., 3(1), 23–34.
Abstract: Chimpanzees follow conspecific and human gaze direction reliably in some situations, but very few chimpanzees reliably use gaze direction or other communicative signals to locate hidden food in the object-choice task. Three studies aimed at exploring factors that affect chimpanzee performance in this task are reported. In the first study, vocalizations and other noises facilitated the performance of some chimpanzees (only a minority). In the second study, various behavioral cues were given in which a human experimenter either touched, approached, or actually lifted and looked under the container where the food was hidden. Each of these cues led to enhanced performance for only a very few individuals. In the third study – a replication with some methodological improvements of a previous experiment – chimpanzees were confronted with two experimenters giving conflicting cues about the location of the hidden food, with one of them (the knower) having witnessed the hiding process and the other (the guesser) not. In the crucial test in which a third experimenter did the hiding, no chimpanzee found the food at above chance levels. Overall, in all three studies, by far the best performers were two individuals who had been raised in infancy by humans. It thus seems that while chimpanzees are very good at “behavior reading” of various sorts, including gaze following, they do not understand the communicative intentions (informative intentions) behind the looking and gesturing of others – with the possible exception of enculturated chimpanzees, who still do not understand the differential significance of looking and gesturing done by people who have different knowledge about states of affairs in the world.
|
|
Call, J. (2002). A fish-eye lens for comparative studies: broadening the scope of animal cognition. Anim. Cogn., 5(1), 15–16.
Abstract: ? is the article no longer available?
|
|
Kaminski, J., Riedel, J., Call, J., & Tomasello, M. (2005). Domestic goats, Capra hircus, follow gaze direction and use social cues in an object choice task. Anim. Behav., 69(1), 11–18.
Abstract: Gaze following is a basic social cognitive skill with many potential benefits for animals that live in social groups. At least five primate species are known to follow the gaze of conspecifics, but there have been no studies on gaze following in other mammals. We investigated whether domestic goats can use the gaze direction of a conspecific as a cue to find food. They were able to do this, at a level comparable to that of primates. In a second experiment, we tested goats' ability to use gaze and other communicative cues given by a human in a so-called object choice situation. An experimenter hid food out of sight of the subject under one of two cups. After baiting the cup the experimenter indicated the location of the food to the subject by using different cues. The goats used communicative cues (touching and pointing) but not gaze by itself. Since domestic dogs are very skilled in this task, whereas wolves are not, one hypothesis is that the use of communicative cues in the object choice task is a side-effect of domestication.
|
|
Abramson, J. Z., Hernández-Lloreda, V., Call, J., & Colmenares, F. (2013). Experimental evidence for action imitation in killer whales (Orcinus orca). Animal Cognition, 16(1), 11–22.
Abstract: Comparative experimental studies of imitative learning have focused mainly on primates and birds. However, cetaceans are promising candidates to display imitative learning as they have evolved in socioecological settings that have selected for large brains, complex sociality, and coordinated predatory tactics. Here we tested imitative learning in killer whales, Orcinus orca. We used a ‘do-as-other-does’ paradigm in which 3 subjects witnessed a conspecific demonstrator’s performance that included 15 familiar and 4 novel behaviours. The three subjects (1) learned the copy command signal ‘Do that’ very quickly, that is, 20 trials on average; (2) copied 100 % of the demonstrator’s familiar and novel actions; (3) achieved full matches in the first attempt for 8–13 familiar behaviours (out of 15) and for the 2 novel behaviours (out of 2) in one subject; and (4) took no longer than 8 trials to accurately copy any familiar behaviour, and no longer than 16 trials to copy any novel behaviour. This study provides experimental evidence for body imitation, including production imitation, in killer whales that is comparable to that observed in dolphins tested under similar conditions. These findings suggest that imitative learning may underpin some of the group-specific traditions reported in killer whales in the field.
|
|
Buttelmann, D., Call, J., & Tomasello, M. (2007). Behavioral cues that great apes use to forage for hidden food. Anim. Cogn., .
Abstract: We conducted three studies to examine whether the four great ape species (chimpanzees, bonobos, gorillas, and orangutans) are able to use behavioral experimenter-given cues in an object-choice task. In the subsequent experimental conditions subjects were presented with two eggs, one of which contained food and the other did not. In Study 1 the experimenter examined both eggs by smelling or shaking them, but only made a failed attempt to open (via biting) the egg containing food. In a control condition, the experimenter examined and attempted to open both eggs, but in reverse order to control for stimulus enhancement. The apes significantly preferred the egg that was first examined and then bitten, but had no preference in a baseline condition in which there were no cues. In Study 2, we investigated whether the apes could extend this ability to cues not observed in apes so far (i.e., attempting to pull apart the egg), as well as whether they made this discrimination based on the function of the action the experimenter performed. Subjects significantly preferred eggs presented with this novel cue, but did not prefer eggs presented with a novel but functionally irrelevant action. In Study 3, apes did not interpret human actions as cues to food-location when they already knew that the eggs were empty. Thus, great apes were able to use a variety of experimenter-given cues associated with foraging actions to locate hidden food and thereby were partially sensitive to the general purpose underlying these actions.
|
|
Albiach-Serrano, A., Guillen-Salazar, F., & Call, J. (2007). Mangabeys (Cercocebus torquatus lunulatus) solve the reverse contingency task without a modified procedure. Anim. Cogn., .
Abstract: Problem solving often relies on generating new responses while inhibiting others, particularly prepotent ones. A paradigm to study inhibitory abilities is the reverse contingency task (Boysen and Berntson in J Exp Psychol Anim Behav Process 21:82-86, 1995), in which two different quantities of food are offered to an individual who receives the array he did not choose. Therefore, mastery of the task demands selecting the smaller quantity to obtain the larger one. Several non-human primates have been tested in the reverse contingency task. To date, only great apes and rhesus monkeys (Macaca mulatta) have succeeded in the original task, with no need of procedural modifications as the large-or-none contingency, correction trials or symbolic stimuli substituting for actual food quantities. Here, four mangabeys were presented with two stimulus arrays of one and four raisins in the context of the reverse contingency task. Three of them learned to perform the task well above chance without a modified procedure. They also reached above-chance performance when presented with two stimulus arrays of zero and four raisins, despite the initial difficulty of choosing a null quantity. After a period of 7-10 months, in which the animals were not tested on any task, all three subjects continued to perform well, even when presented with novel quantity pairs.
|