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Rybarczyk, P., Koba, Y., Rushen, J., Tanida, H., & de Passille, A. M. (2001). Can cows discriminate people by their faces? Appl. Anim. Behav. Sci., 74(3), 175–189.
Abstract: This experiment examines the cues used by cattle to discriminate between people, particularly the role played by facial cues. We trained and tested eight Holstein cows 5 days each week for 2 months. For each cow, we used two people, a rewarder and a non-rewarder, of different size and dressed in overalls of the same colour. The operant chamber was a large box within which stood the two people. The cow could see, smell and touch each person. A lever was placed in front of each person. When the cow pushed the lever in front of the rewarder, it received 75 g of concentrate and nothing when it pushed on the other one. For each test session, the cows made 10 choices. The placement of the people was determined randomly according to the Gellerman series. The success criterion was defined as at least eight correct choices out of 10 trials for two consecutive sessions (binomial law P<0.003). During the shaping, seven cows out of eight learned to press the lever to obtain the food. The cows were then tested in a series of 10 trials with only the rewarder present. Seven out of seven cows succeeded in reaching the success criterion. In experiment 1, both the rewarder and the non-rewarder were present and standing upright at normal height and in full view of the cow. Five out of seven cows achieved the success criterion. In experiment 2, the cows could see only the faces of the two people. None of the cows were able to reach the success criterion. In experiment 3, both people were present standing up and wearing identical masks that completely covered their heads. Five cows out of five achieved the success criterion. In experiment 4, we changed the relative height of the people. Five cows out of five succeeded when the two people stood so they were of equal height but with their faces visible. However, no cows succeeded when the people were both of equal height and had their faces covered. This study suggests that cows seem to use multiple cues to discriminate between people. Cows appear able to use either body height or the face to discriminate between people but use of the face alone is more difficult when the cows cannot see the rest of the body.
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Dougherty, D. M., & Lewis, P. (1991). Stimulus generalization, discrimination learning, and peak shift in horses. J Exp Anal Behav, 56(1), 97–104.
Abstract: Using horses, we investigated three aspects of the stimulus control of lever-pressing behavior: stimulus generalization, discrimination learning, and peak shift. Nine solid black circles, ranging in size from 0.5 in. to 4.5 in. (1.3 cm to 11.4 cm) served as stimuli. Each horse was shaped, using successive approximations, to press a rat lever with its lip in the presence of a positive stimulus, the 2.5-in. (6.4-cm) circle. Shaping proceeded quickly and was comparable to that of other laboratory organisms. After responding was maintained on a variable-interval 30-s schedule, stimulus generalization gradients were collected from 2 horses prior to discrimination training. During discrimination training, grain followed lever presses in the presence of a positive stimulus (a 2.5-in circle) and never followed lever presses in the presence of a negative stimulus (a 1.5-in. [3.8-cm] circle). Three horses met a criterion of zero responses to the negative stimulus in fewer than 15 sessions. Horses given stimulus generalization testing prior to discrimination training produced symmetrical gradients; horses given discrimination training prior to generalization testing produced asymmetrical gradients. The peak of these gradients shifted away from the negative stimulus. These results are consistent with discrimination, stimulus generalization, and peak-shift phenomena observed in other organisms.
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Barrett, L., & Henzi, P. (2005). The social nature of primate cognition. Proc Biol Sci, 272(1575), 1865–1875.
Abstract: The hypothesis that the enlarged brain size of the primates was selected for by social, rather than purely ecological, factors has been strongly influential in studies of primate cognition and behaviour over the past two decades. However, the Machiavellian intelligence hypothesis, also known as the social brain hypothesis, tends to emphasize certain traits and behaviours, like exploitation and deception, at the expense of others, such as tolerance and behavioural coordination, and therefore presents only one view of how social life may shape cognition. This review outlines work from other relevant disciplines, including evolutionary economics, cognitive science and neurophysiology, to illustrate how these can be used to build a more general theoretical framework, incorporating notions of embodied and distributed cognition, in which to situate questions concerning the evolution of primate social cognition.
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Call, J. (2006). Inferences by exclusion in the great apes: the effect of age and species. Anim. Cogn., 9(4), 393–403.
Abstract: This study investigated the ability of chimpanzees, gorillas, orangutans, and bonobos to make inferences by exclusion using the procedure pioneered by Premack and Premack (Cognition 50:347-362, 1994) with chimpanzees. Thirty apes were presented with two different food items (banana vs. grape) on a platform and covered with identical containers. One of the items was removed from the container and placed between the two containers so that subjects could see it. After discarding this item, subjects could select between the two containers. In Experiment 1, apes preferentially selected the container that held the item that the experimenter had not discarded, especially if subjects saw the experimenter remove the item from the container (but without seeing the container empty). Experiment 3 in which the food was removed from one of the containers behind a barrier confirmed these results. In contrast, subjects performed at chance levels when a stimulus (colored plastic chip: Exp. 1; food item: Exp. 2 and Exp. 3) designated the item that had been removed. These results indicated that apes made inferences, not just learned to use a discriminative cue to avoid the empty container. Apes perceived and treated the item discarded by the experimenter as if it were the very one that had been hidden under the container. Results suggested a positive relationship between age and inferential ability independent of memory ability but no species differences.
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Watanabe, S., & Huber, L. (2006). Animal logics: decisions in the absence of human language. Anim. Cogn., 9(4), 235–245.
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Regolin, L., Marconato, F., & Vallortigara, G. (2004). Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus). Anim. Cogn., 7(3), 162–170.
Abstract: Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders (“amodal completion”). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a “global” analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a “featural” analysis of visual scenes.
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Anderson, J. R., Kuroshima, H., Kuwahata, H., & Fujita, K. (2004). Do squirrel monkeys (Saimiri sciureus) and capuchin monkeys (Cebus apella) predict that looking leads to touching? Anim. Cogn., 7(3), 185–192.
Abstract: Squirrel monkeys (Saimiri sciureus) and capuchin monkeys (Cebus apella) were tested using an expectancy violation procedure to assess whether they use an actor's gaze direction, signaled by congruent head and eye orientation, to predict subsequent behavior. The monkeys visually habituated to a repeated sequence in which the actor (a familiar human or a puppet) looked at an object and then picked it up, but they did not react strongly when the actor looked at an object but then picked up another object. Capuchin monkeys' responses in the puppet condition were slightly more suggestive of expectancy. There was no differential responding to congruent versus incongruent look-touch sequences when familiarization trials were omitted. The weak findings contrast with a strongly positive result previously reported for tamarin monkeys. Additional evidence is required before concluding that behavior prediction based on gaze cues typifies primates; other approaches for studying how they process attention cues are indicated.
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Gácsi, M., Miklósi, Á., Varga, O., Topál, J., & Csányi, V. (2004). Are readers of our face readers of our minds? Dogs (Canis familiaris) show situation-dependent recognition of human's attention. Anim. Cogn., 7(3), 144–153.
Abstract: The ability of animals to use behavioral/facial cues in detection of human attention has been widely investigated. In this test series we studied the ability of dogs to recognize human attention in different experimental situations (ball-fetching game, fetching objects on command, begging from humans). The attentional state of the humans was varied along two variables: (1) facing versus not facing the dog; (2) visible versus non-visible eyes. In the first set of experiments (fetching) the owners were told to take up different body positions (facing or not facing the dog) and to either cover or not cover their eyes with a blindfold. In the second set of experiments (begging) dogs had to choose between two eating humans based on either the visibility of the eyes or direction of the face. Our results show that the efficiency of dogs to discriminate between “attentive” and “inattentive” humans depended on the context of the test, but they could rely on the orientation of the body, the orientation of the head and the visibility of the eyes. With the exception of the fetching-game situation, they brought the object to the front of the human (even if he/she turned his/her back towards the dog), and preferentially begged from the facing (or seeing) human. There were also indications that dogs were sensitive to the visibility of the eyes because they showed increased hesitative behavior when approaching a blindfolded owner, and they also preferred to beg from the person with visible eyes. We conclude that dogs are able to rely on the same set of human facial cues for detection of attention, which form the behavioral basis of understanding attention in humans. Showing the ability of recognizing human attention across different situations dogs proved to be more flexible than chimpanzees investigated in similar circumstances.
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West, R. E., & Young, R. J. (2002). Do domestic dogs show any evidence of being able to count? Anim. Cogn., 5(3), 183–186.
Abstract: Numerical competence has been demonstrated in a wide range of animal species. The level of numerical abilities shown ranges from simple relative numerousness judgements to true counting. In this study we used the preferential looking technique to test whether 11 pet dogs could count. The dogs were presented with three simple calculations: “1+1=2”; “1+1=1”; and “1+1=3”. These calculations were performed by presenting the dogs with treats that were placed behind a screen that allowed manipulation of the outcome of the calculation. When the dogs expected the outcome they spent the same amount of time looking at the result of the calculation as they did on the initial presentation. However, when the result was unexpected dogs spent significantly longer looking at the outcome of the calculation. The results suggest that the dogs were anticipating the outcome of the calculations they observed, thus suggesting that dogs may have a rudimentary ability to count.
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Pepperberg, I. M. (2002). The value of the Piagetian framework for comparative cognitive studies. Anim. Cogn., 5(3), 177–182.
Abstract: Although the Piagetian framework has been used by numerous researchers to compare cognitive abilities of diverse species, the system is often criticized as implemented. I examine the various criticisms, suggest ways in which the system can be improved, and argue for the need for descriptive systems such as the Piagetian framework to complement programs that look for cellular and molecular bases or mathematical models to explain behavior.
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