- Email: [email protected]
Exploring the canine mind: Studies of dog cognition
G Model YLMOT-1405; No. of Pages 2
ARTICLE IN PRESS Learning and Motivation xxx (2013) xxx–xxx
Contents lists available at SciVerse ScienceDirect
Learning and Motivation journal homepage: www.elsevier.com/locate/l&m
Introduction
Exploring the canine mind: Studies of dog cognition
Ten years ago, the prospect of dedicating an entire special issue to the topic of dog cognition would have been unlikely, to say the least. Despite very early interest in the cognitive realm of the domestic dog by Darwin and Romanes, dogs were often viewed as an artificial species due to their domestication. New interest in the dog as a subject of study came about, however, as small groups of researchers in both Europe and North America began to posit that it is precisely because of their domestication that dogs are of such interest to psychological research. Dogs are thought to have been domesticated approximately 12,000–14,000 years ago (Vila et al., 1997) and have since come to occupy an anthropogenic niche. Even among other domesticated species, dogs are unique—no other species has been selectively bred to attend to human beings in the way that the domestic dog has. Dogs have been bred to hunt our prey, herd our livestock, guard our homes, and of course to be our companions, among other things. Although it is hard to generate an exact figure, in the United States, Canada, and Eastern Europe (where the articles in this special issue are from), there are approximately 73 million, 6 million and 43 million pet dogs, respectively (Coren, 2012). Even the most casual dog owner speculates about the cognitive world of his/her pet—and so a welcome benefit of the field of dog cognition is that it attracts an amount of public interest that is typically unusual in comparative cognition. This widespread interest in the topic of dog cognition seems all the more reason to put together this comprehensive special issue. The papers contained in this volume cover a variety of topics in canine cognition, including sensory processes, a variety of cognitive abilities, and the influence of human cuing on cognitive decisions made by dogs. The vast majority of research on dog cognition has used visual cuing of one sort or another, perhaps because vision is the dominant sense used by the primate human experimenters. It is important to keep in mind, however, that the sense of smell, and not vision, is the dominant sense used by canines. Thus, research that reveals the extent to which dogs use odor cues to learn and solve problems is of considerable value in our quest to understand dog cognition. Two articles in this volume address this concern. Although dogs have been trained to use their sense of smell to specifically detect human scent (tracking), drugs, explosives, and disease, it is of interest to know the extent to which non-trained dogs may use odor cues. Odor cues are often controlled in dog cognition experiments with pet dogs to guard against the possibility that dogs might detect the location of a food reward through smell and not through other cues (often visual) arranged by the experimenter. Are such controls necessary? Horowitz, Hecht, and Dedrick examined dogs preference for closed plates containing one versus five pieces of food (hot dog). Surprisingly, dogs showed no significant preference for the larger-quantity plate. Hall, Smith, and Wynne showed that domestic dogs can be trained to detect a distinct odor (anise) buried in pine shavings. However, it took dogs about 60 trials to reach an average performance level of 80% correct choices, and dogs learned much better when a human experimenter delivered food reward than when the reward was buried with the odor cue. These interesting studies suggest that domestic dogs may not spontaneously make odor discriminations between quantities of food but may be trained to attend to and discriminate between the presence and absence of an odor cue. Among the cognitive processes studied in animals, language has been one of the most controversial, as issues concerning interspecies differences in comprehension of language structure have repeatedly arisen. In a landmark study, Pilley and Reid (2011) reported a long-term study of a border collie, Chaser, that was trained to discriminate among the names (proper nouns) for over 1000 objects; further, Chaser learned the names of new objects through a process of exclusion. In this volume, Pilley reports more recent studies that build on Chaser’s vocabulary by examining her comprehension of simple sentences. Based on earlier language investigations with dolphins (Herman, Richards, & Wolz, 1984), studies are reported suggesting that Chaser understands the syntactical relationships within imperative sentences containing a prepositional object, verb, and direct object. Although precise counting based on assignment of number symbols to objects appears reserved to humans, counting using an approximate number system (ANS) has been shown repeatedly in adult humans, infants, and non-human 0023-9690/$ – see front matter © 2013 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.lmot.2013.04.006
Please cite this article in press as: Macpherson, K., & Roberts, W.A. Exploring the canine mind: Studies of dog cognition. Learning and Motivation (2013), http://dx.doi.org/10.1016/j.lmot.2013.04.006
G Model YLMOT-1405; No. of Pages 2
ARTICLE IN PRESS Introduction / Learning and Motivation xxx (2013) xxx–xxx
2
primates (Merritt, DeWind, & Brannon, 2012). Macpherson and Roberts report two studies that looked for evidence of the ANS in dogs. When tested for discrimination between smaller and larger quantities of items, dogs failed to do so when items were presented sequentially. When shown different numbers of patterns simultaneously, however, a rough collie (Sedona) showed clear evidence of discrimination that obeyed Weber’s law; accuracy varied systematically as the smaller/larger number ratio changed. Another classic problem in the field of animal cognition has been to achieve an understanding of how a nonverbal animal represents and remembers a complex stimulus. This question has often been studied by exposing an animal to one depiction of a stimulus and then examining how it responds to systematic changes in the stimulus. Does it detect some changes and not others? Pattison, Laude, and Zentall address this question with dogs in “The case of the magic bones.” Using a procedure popular with preverbal infant researchers, they allowed dogs to initially observe a bone and then to subsequently view the bone changed in either size or color. Dogs gazed longer at a bone changed in either way, compared to a control presentation of an unchanged bone. Dogs apparently encoded and remembered both the size and color of the bone. Huber, Racca, Scaf, Viranyi, and Range report on dogs’ memory for an even more complex stimulus—the human face. Dogs trained to discriminate between human faces were then tested for their ability to discriminate when only certain facial features were shown. The complex findings suggest differences among dogs in features used to identify a human face. The degree to which human cuing controls dog behavior has been a focus of major interest in the recent study of canine cognition (Hare, Brown, Williamson, & Tomasello, 2002). Control of dog behavior by human pointing was shown in two papers reported in this volume, even though the dog’s response contradicted its natural preference. Pongracz, Hegedus, Sanjurjo, Kovari, and Miklosi found that dogs would repeatedly choose a bowl containing a carrot over a bowl containing preferred sausage if a human pointed to the carrot bowl. In a delayed response test, dogs regularly search at the location where they last saw food disappear. Plourde and Fiset showed, however, that dogs would search instead at an alternative location if that location was pointed at by a human experimenter. Although both papers report some modification of dogs’ choices over repeated trials, these articles again show the strong control human direction exerts over dog behavior. This special issue provides a sampler of the exciting topics now being pursued in the field of canine cognition. They range from exploration of basic sensory processes to studies of cognitive abilities dogs may share with humans to investigations of dog-human social interaction. We hope that these articles promote yet further research in the emerging field of dog cognition. References Coren, S. (2012). How many dogs are there in the world? Psychology Today, September. Hare, B., Brown, M., Williamson, C., & Tomasello, M. (2002). The domestication of social cognition in dogs. Science, 298, 1634–1636. Herman, L. M., Richards, D. G., & Wolz, J. P. (1984). Comprehension of sentences by bottlenosed dolphins. Cognition, 16, 129–219. Merritt, D. J., DeWind, N. K., & Brannon, E. M. (2012). Comparative cognition of number representation. In T. R. Zentall, & E. A. Wasserman (Eds.), The Oxford handbook of comparative cognition (pp. 451–476). Oxford, UK: Oxford University Press. Pilley, J. W., & Reid, A. K. (2011). Border collie comprehends object names as verbal referents. Behavioural Processes, 86, 184–195. Vila, C., Savolainen, P., Maldonado, J. E., Amorin, I. R., Rice, J. E., Honeycutt, R. L., et al. (1997). Multiple and ancient origins of the domestic dog. Science, 276(June), 1687–1689.
Krista Macpherson ∗ William A. Roberts Department of Psychology, Western University, London, Ontario, Canada N6A 5C2 ∗ Corresponding
author. E-mail addresses: [email protected] (K. Macpherson), [email protected] (W.A. Roberts) Available online xxx
Please cite this article in press as: Macpherson, K., & Roberts, W.A. Exploring the canine mind: Studies of dog cognition. Learning and Motivation (2013), http://dx.doi.org/10.1016/j.lmot.2013.04.006
ARTICLE IN PRESS Learning and Motivation xxx (2013) xxx–xxx
Contents lists available at SciVerse ScienceDirect
Learning and Motivation journal homepage: www.elsevier.com/locate/l&m
Introduction
Exploring the canine mind: Studies of dog cognition
Ten years ago, the prospect of dedicating an entire special issue to the topic of dog cognition would have been unlikely, to say the least. Despite very early interest in the cognitive realm of the domestic dog by Darwin and Romanes, dogs were often viewed as an artificial species due to their domestication. New interest in the dog as a subject of study came about, however, as small groups of researchers in both Europe and North America began to posit that it is precisely because of their domestication that dogs are of such interest to psychological research. Dogs are thought to have been domesticated approximately 12,000–14,000 years ago (Vila et al., 1997) and have since come to occupy an anthropogenic niche. Even among other domesticated species, dogs are unique—no other species has been selectively bred to attend to human beings in the way that the domestic dog has. Dogs have been bred to hunt our prey, herd our livestock, guard our homes, and of course to be our companions, among other things. Although it is hard to generate an exact figure, in the United States, Canada, and Eastern Europe (where the articles in this special issue are from), there are approximately 73 million, 6 million and 43 million pet dogs, respectively (Coren, 2012). Even the most casual dog owner speculates about the cognitive world of his/her pet—and so a welcome benefit of the field of dog cognition is that it attracts an amount of public interest that is typically unusual in comparative cognition. This widespread interest in the topic of dog cognition seems all the more reason to put together this comprehensive special issue. The papers contained in this volume cover a variety of topics in canine cognition, including sensory processes, a variety of cognitive abilities, and the influence of human cuing on cognitive decisions made by dogs. The vast majority of research on dog cognition has used visual cuing of one sort or another, perhaps because vision is the dominant sense used by the primate human experimenters. It is important to keep in mind, however, that the sense of smell, and not vision, is the dominant sense used by canines. Thus, research that reveals the extent to which dogs use odor cues to learn and solve problems is of considerable value in our quest to understand dog cognition. Two articles in this volume address this concern. Although dogs have been trained to use their sense of smell to specifically detect human scent (tracking), drugs, explosives, and disease, it is of interest to know the extent to which non-trained dogs may use odor cues. Odor cues are often controlled in dog cognition experiments with pet dogs to guard against the possibility that dogs might detect the location of a food reward through smell and not through other cues (often visual) arranged by the experimenter. Are such controls necessary? Horowitz, Hecht, and Dedrick examined dogs preference for closed plates containing one versus five pieces of food (hot dog). Surprisingly, dogs showed no significant preference for the larger-quantity plate. Hall, Smith, and Wynne showed that domestic dogs can be trained to detect a distinct odor (anise) buried in pine shavings. However, it took dogs about 60 trials to reach an average performance level of 80% correct choices, and dogs learned much better when a human experimenter delivered food reward than when the reward was buried with the odor cue. These interesting studies suggest that domestic dogs may not spontaneously make odor discriminations between quantities of food but may be trained to attend to and discriminate between the presence and absence of an odor cue. Among the cognitive processes studied in animals, language has been one of the most controversial, as issues concerning interspecies differences in comprehension of language structure have repeatedly arisen. In a landmark study, Pilley and Reid (2011) reported a long-term study of a border collie, Chaser, that was trained to discriminate among the names (proper nouns) for over 1000 objects; further, Chaser learned the names of new objects through a process of exclusion. In this volume, Pilley reports more recent studies that build on Chaser’s vocabulary by examining her comprehension of simple sentences. Based on earlier language investigations with dolphins (Herman, Richards, & Wolz, 1984), studies are reported suggesting that Chaser understands the syntactical relationships within imperative sentences containing a prepositional object, verb, and direct object. Although precise counting based on assignment of number symbols to objects appears reserved to humans, counting using an approximate number system (ANS) has been shown repeatedly in adult humans, infants, and non-human 0023-9690/$ – see front matter © 2013 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.lmot.2013.04.006
Please cite this article in press as: Macpherson, K., & Roberts, W.A. Exploring the canine mind: Studies of dog cognition. Learning and Motivation (2013), http://dx.doi.org/10.1016/j.lmot.2013.04.006
G Model YLMOT-1405; No. of Pages 2
ARTICLE IN PRESS Introduction / Learning and Motivation xxx (2013) xxx–xxx
2
primates (Merritt, DeWind, & Brannon, 2012). Macpherson and Roberts report two studies that looked for evidence of the ANS in dogs. When tested for discrimination between smaller and larger quantities of items, dogs failed to do so when items were presented sequentially. When shown different numbers of patterns simultaneously, however, a rough collie (Sedona) showed clear evidence of discrimination that obeyed Weber’s law; accuracy varied systematically as the smaller/larger number ratio changed. Another classic problem in the field of animal cognition has been to achieve an understanding of how a nonverbal animal represents and remembers a complex stimulus. This question has often been studied by exposing an animal to one depiction of a stimulus and then examining how it responds to systematic changes in the stimulus. Does it detect some changes and not others? Pattison, Laude, and Zentall address this question with dogs in “The case of the magic bones.” Using a procedure popular with preverbal infant researchers, they allowed dogs to initially observe a bone and then to subsequently view the bone changed in either size or color. Dogs gazed longer at a bone changed in either way, compared to a control presentation of an unchanged bone. Dogs apparently encoded and remembered both the size and color of the bone. Huber, Racca, Scaf, Viranyi, and Range report on dogs’ memory for an even more complex stimulus—the human face. Dogs trained to discriminate between human faces were then tested for their ability to discriminate when only certain facial features were shown. The complex findings suggest differences among dogs in features used to identify a human face. The degree to which human cuing controls dog behavior has been a focus of major interest in the recent study of canine cognition (Hare, Brown, Williamson, & Tomasello, 2002). Control of dog behavior by human pointing was shown in two papers reported in this volume, even though the dog’s response contradicted its natural preference. Pongracz, Hegedus, Sanjurjo, Kovari, and Miklosi found that dogs would repeatedly choose a bowl containing a carrot over a bowl containing preferred sausage if a human pointed to the carrot bowl. In a delayed response test, dogs regularly search at the location where they last saw food disappear. Plourde and Fiset showed, however, that dogs would search instead at an alternative location if that location was pointed at by a human experimenter. Although both papers report some modification of dogs’ choices over repeated trials, these articles again show the strong control human direction exerts over dog behavior. This special issue provides a sampler of the exciting topics now being pursued in the field of canine cognition. They range from exploration of basic sensory processes to studies of cognitive abilities dogs may share with humans to investigations of dog-human social interaction. We hope that these articles promote yet further research in the emerging field of dog cognition. References Coren, S. (2012). How many dogs are there in the world? Psychology Today, September. Hare, B., Brown, M., Williamson, C., & Tomasello, M. (2002). The domestication of social cognition in dogs. Science, 298, 1634–1636. Herman, L. M., Richards, D. G., & Wolz, J. P. (1984). Comprehension of sentences by bottlenosed dolphins. Cognition, 16, 129–219. Merritt, D. J., DeWind, N. K., & Brannon, E. M. (2012). Comparative cognition of number representation. In T. R. Zentall, & E. A. Wasserman (Eds.), The Oxford handbook of comparative cognition (pp. 451–476). Oxford, UK: Oxford University Press. Pilley, J. W., & Reid, A. K. (2011). Border collie comprehends object names as verbal referents. Behavioural Processes, 86, 184–195. Vila, C., Savolainen, P., Maldonado, J. E., Amorin, I. R., Rice, J. E., Honeycutt, R. L., et al. (1997). Multiple and ancient origins of the domestic dog. Science, 276(June), 1687–1689.
Krista Macpherson ∗ William A. Roberts Department of Psychology, Western University, London, Ontario, Canada N6A 5C2 ∗ Corresponding
author. E-mail addresses: [email protected] (K. Macpherson), [email protected] (W.A. Roberts) Available online xxx
Please cite this article in press as: Macpherson, K., & Roberts, W.A. Exploring the canine mind: Studies of dog cognition. Learning and Motivation (2013), http://dx.doi.org/10.1016/j.lmot.2013.04.006