10/28/2015 Comparative ­ Psychology ­ Oxford Bibliographies

Comparative Psychology Sarah Brosnan, Katie Hall

LAST MODIFIED: 26 OCTOBER 2015 DOI: 10.1093/OBO/9780199828340­0176

Introduction

Comparative psychology, a subdiscipline of psychology, is the scientific study of the behavior and cognition of human and non­ human animals, with emphasis on how behavior relates to phylogeny, ontogeny, and adaptation. Rooted in evolutionary principles, the field of comparative psychology seeks to answer a multitude of questions on a variety of species, with particular interest in how it relates to human behavior. While individual studies may not explicitly compare two or more species, the general focus is on comparing species, including humans, across one or more dimensions. Data contributed to the field from only one species are still valuable in that they may provide a point of comparison for future studies, or may help in developing general principles of animal psychology when pooled with studies of other species. Comparative psychology emerged in the late 1800s, as ’s evolutionary principles a framework for asking questions about relationships between species and the similarities and differences in their behavior, and as Georges Cuvier’s comparative method in biology was being adopted in other scientific fields. Cuvier’s student, Pierre Flourens, an eminent researcher on the localized functions of different areas in the brain, published Psychologie Comparée in 1865, in which he proposed comparing humans and non­ humans, and introduced the name of this new field of study. Shortly after, in 1882, Darwin’s student, George John Romanes, published Animal , in which he described a mental hierarchy among animals from least to most advanced, thus setting the foundation for the comparative aspect of comparative psychology. There was a backlash against Romanes’ use of (i.e., the attribution of humanlike qualities to animals) and also frustration over his collection of individual anecdotes rather than a controlled data set. This influenced C. Lloyd Morgan to suggest that animal behavior should not be interpreted in terms of complex psychological processes, when simpler explanations will suffice. Thus, comparative set about collecting data in controlled experiments to elicit and investigate particular behavior in animals and set a high standard for assuming higher­order, humanlike traits in species other than humans. Whereas the original goal of comparative psychology may have been to arrange species in some sort of hierarchy of intelligence, as Romanes began to do, contemporary psychologists now emphasize reference to differences in ecology, social structure, genetics, etc., in explaining differences in behavior.

General Overviews

Historically, “intelligent” has referred to behavior that researchers value, but the field is seeing a shift toward investigating the adaptive function of behavior: that is, behavior valuable to the study subjects. Due to the experimental aspect of comparative psychology, there has been a historical need to differentiate the field from (the observation of natural animal behavior), though many overlaps in ideas, topics, and goals continue to exist. Additionally, there was a geographic split between the two fields, with ethologists based in Europe and comparative psychologists in the United States. Ethology began in the 1930s and was recognized internationally with biologists , , and sharing a Nobel Prize in 1973 for their contributions to the field (von Frisch 1967, Lorenz 1981, Tinbergen 1963). Ethology focuses more on animals’ instinctual responses to stimuli through fixed action patterns, as well as developmental processes of , habituation, and http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 1/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies associative . Behavioral development and comparative psychology, penned by a comparative , argued against the ethologists’ strict dichotomies of innate versus learned behaviors, and instead advocated for better research on behavioral development (Schneirla 1966). , a subfield of psychology spearheaded by Skinner 1938 is the study of trained responses in a laboratory setting, with interest in making predictions from directly observable behavior without reference to internal states, either physiological or mental, following Morgan’s canon. Behaviorism focused on operant (instrumental) and classical (Pavlovian) conditioning. Behaviorism emerged in the early 20th century and, although no longer the dominant view, has become more focused on emergent properties following a cognitive revolution mid­century. Comparative psychology is influenced by related disciplines such as (the study of the evolutionary basis for behavior due to ecological pressures, following Tinbergen’s four questions on the adaptation, phylogeny, mechanism, and ontogeny of a behavior), (studying the mental processes that control complex behavior), (studying whether psychological traits common among human cultures are evolved adaptations), and (identifying the neural processes that underlie behavior). There are scholarly intersections among these fields, and currently there is a focus on a blending of ideas and methods, as is exemplified in the proliferation of “field experiments” (i.e., the use of a controlled experiment in a species’ natural environment that allows animals to interact with a device).

Flourens, P. 1865. Psychologie comparée. Paris: Garnier frères. The author proposes comparing the brain and cognition of human and non­human animals.

Lorenz, K. Z. 1981. The foundations of ethology. New York: Springer Verlag. Another classic text from ethology that offers a historical perspective of the field.

Morgan, C. L. 1903. An introduction to comparative psychology. Bristol, UK: W. Scott. Morgan reacted to the contemporary anthropomorphic descriptions of animal behavior by suggesting that if a more simple explanation exists, it is more parsimonious to accept it in lieu of a more complex one.

Romanes, G. J. 1904. Animal intelligence. London: Kegan Paul, Trench, Trübner. Romanes details the cognitive achievements of various animals through anthropomorphized anecdotes. Although it was determined that his approach to the study of animal behavior was fraudulent, Romanes’s work inspired a more rigorous science to develop.

Schneirla, T. C. 1966. Behavioral development and comparative psychology. Quarterly Review of Biology, 283–302. Schneirla argues that insufficient research has been dedicated to the ontogeny of behavioral differences and decries the damaging effect of the contemporary emphasis on research on the study of development. He advances a developmental theory based on redefining and coupling the concepts of maturation and experience.

Skinner, B. F. 1938. The behavior of organisms: An experimental analysis. Oxford: Appleton­Century. A classic text from the subfield of behaviorism, this book includes a decade of work describing the use of operant chambers to test . Skinner defines the basic unit of behavior (the operant) and its measurement (rate). Whereas respondent behavior is caused by an observable , operant behavior is not.

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Tinbergen, N. 1963. On aims and methods of ethology. Zeitschrift für Tierpsychologie 20.4: 410–433. Another classic text from ethology in which Tinbergen establishes his four questions to explain behavior: function/adaptation, phylogeny, mechanism/causation, ontogeny.

von Frisch, K. 1967. The dance language and orientation of bees. Cambridge, MA: Harvard Univ. Press. This classic text from ethology details the decades of experiments conducted on honeybees to learn more about their communication, sensory , and navigation through the environment.

Textbooks

As the field of comparative psychology became established, there was a need not only to differentiate from other fields but also to synthesize overlapping areas of study; Hinde 1966 attempted to integrate comparative psychology with ethology, but left out any discussion of the of behavior. Dewsbury’s definitive 1984 text placed comparative psychology in its historical context, and differentiated itself from (as well as found common ground between) other fields. Vonk and Shackelford 2012 picked up where Hinde left off to attempt to integrate this evolutionary aspect more explicitly under the umbrella of comparative psychology. Papini 2008 also addresses the evolutionary and developmental aspects of comparative psychology, including humans. General textbooks that introduce topics in the field, including but not limited to perception, attention, memory, spatial cognition, timing and counting, categorization, pattern learning, tool use, problem solving, and , are Greenberg and Haraway 1998, Shettleworth 2010, and Wasserman and Zentall 2006. The exercise book from Ploger and Yasukawa 2003 is a helpful tool for educators and students alike in guiding the process of scientific inquiry.

Dewsbury, D. A. 1984. Comparative psychology in the twentieth century. Stroudsburg, PA: Hutchinson Ross. Dewsbury begins by defining comparative psychology in its historical context, addressing and rejecting common misconceptions and critiques. He describes who psychologists are and defines topics and species of study. Chapters are dedicated to various topics in the discipline, from associative and , to counting, mirror self­recognition, and tool use.

Greenberg, G., and M. M. Haraway. 1998. Comparative psychology: A handbook (Garland Reference Library of Social Science). New York: Taylor and Francis. Papers discuss theories and issues of comparative psychology and related disciplines (behavioral ecology, ). The text has sections on physiology and perception, learning and development, various topics ranging from foraging to , and a section on cognitive processes.

Hinde, R. 1966. Animal Behavior: A synthesis of ethology and comparative psychology. New York: McGraw­Hill. Hinde tries to find common ground between ethology and comparative psychology but leaves out discussions of adaptive function and evolution of behavior.

Papini, M. R. 2008. Comparative psychology: Evolution and development of behavior. 2d ed. New York: Psychology Press. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 3/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies This textbook focuses on evolutionary and developmental approaches to the study of animal behavior, and has many examples of human behavior, including two chapters on infant learning.

Ploger, B. J., and K. Yasukawa, eds. 2003. Exploring animal behavior in laboratory and field: An hypothesis­testing approach to the development, causation, function, and evolution of animal behavior. Amsterdam: Academic. This supplementary book of over thirty exercises, based on teaching expertise from members of the Animal Behavior Society, helps students learn the entire process of scientific inquiry, from the generation of research hypotheses, to data collection, and interpretation of results. Recommended as a resource guide for educators.

Shettleworth, S. J. 2010. Cognition, evolution, and behavior. 2d ed. New York: Oxford Univ. Press. This text has sections on fundamental mechanisms, physical, and social cognition. It synthesizes work from behavioral ecology and comparative psychology to address questions from species­specific adaptations to the environment, to theory of capacities in great apes, corvids, and domesticated dogs. This edition also includes a chapter on brain evolution.

Vonk, J., and T. K. Shackelford, eds. 2012. The Oxford handbook of comparative evolutionary psychology. New York: Oxford Univ. Press. The editors argue that comparative psychologists, creative in experimental design, lose sight of answering the questions of proximate and ultimate causation (i.e., the theoretical framework of evolutionary psychologists) and that both should work together. This volume truly integrates the comparative aspect of the field(s) by covering the convergent evolution of cognition.

Wasserman, E. A., and T. R. Zentall, eds. 2006. : Experimental explorations of animal intelligence. Oxford: Oxford Univ. Press. This text has sections on perception, attention, memory, spatial cognition, timing and counting, categorization, pattern learning, tool use, problem solving, and social cognition.

Journals

The following peer­reviewed scientific journals publish empirical and theoretical research relevant to the field of comparative psychology. Most influential in the field are Animal Cognition and Journal of Comparative Psychology; the latter is published by the American Psychological Association. Behavioural Processes has a broad scope. Journal of : Animal Learning and Cognition (formerly known as Animal Behavior Processes) and Learning and Behavior (formerly known as Animal Learning and Behavior) both publish experimental and theoretical papers on a range of topics in the field.

Animal Cognition. This journal publishes interdisciplinary work on animal cognition from an evolutionary perspective. It covers topics including numerical competence, time perception, innate learning, symbolic communication, tool use and problem solving.

Behavioural Processes. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 4/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies This journal publishes research on any aspect of animal behavior, from the fields of cognition, ethology, evolution, and ecology.

Journal of Comparative Psychology. Published by the American Psychological Association, this journal encourages publication of research with more than one subject species and/or more than one experimental task. Topics include behavior genetics, conservation and welfare, animal models in robotics, endocrine­behavior interactions, personality research and much more.

Journal of Experimental Psychology: Animal Learning and Cognition. Also published by the American Psychological Association, this journal publishes experimental and theoretical work on associative, non­associative, cognitive, perceptual, and motivational processes. It publishes empirical reports and reviews, as well as brief communications.

Learning & Behavior. Published by the Psychonomic Society, this journal focuses on sensation, perception, conditioning, learning, attention, memory, , , development, social behavior, and comparative investigations.

Related Journals

Papers on animal behavior or cognition and other topics related to comparative psychology are often published in relevant journals. Behaviour and Ethology publish on behavior observed under natural conditions, whereas Behavioral Neuroscience publishes studies in which the is observed or manipulated to determine how behavior is produced. Animal Behaviour covers a broad range of topics and species.

Animal Behaviour. Published for the Association for the Study of Animal Behavior in collaboration with Animal Behavior Society. Topics of interest include ethology, behavioral ecology, sociobiology, behavioral psychology, and behavioral physiology.

Behaviour. Founded by Nobel Prize winner Niko Tinbergen and W. H. Thorpe, this journal seeks to answer Tinbergen’s four questions on the proximate and ultimate causation of behavior. Although controlled laboratory experiments are published, emphasis has always been on publishing examples of behavior observed under natural conditions.

Behavioral Neuroscience. Focuses on research in which some part of the nervous system is observed or manipulated to determine how it produces behavior in an organism. Neural imaging techniques are encouraged.

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Ethology. This journal publishes laboratory and field experiments on animal behavior including physiological mechanisms, function, and evolution.

Related Texts and Papers

Lehrman 1953 offers several major critiques to the instinct theory developed in ethology, in particular using the comparative method to study evolutionary levels of behavior. Krebs and Davies 1997 is a behavioral ecology textbook that may also help to contextualize comparative psychology. Altmann 1974 is a paper on observational sampling methods that has been fundamental to the field. The journal Behavioral and Brain Sciences offers a unique format to stimulate conversation. Online resources include Dr. Robert Cook’s Homepage Department of Psychology.

Altmann, J. (1974). Observational study of behavior: Sampling methods. Behaviour 49.3–4: 227–267. Altmann describes seven types of behavioral sampling methods: Ad libitum, sociometric matrix completion, focal animal, all­ occurrences, sequence, one­zero, instantaneous, and scan sampling. This is the first paper to advocate for consistent sampling across studies, which allows for findings across species and contexts to be more rigorously compared.

Behavioral and Brain Sciences. The open peer commentary format of this journal stimulates conversation over controversial research: issues include a paper, with comments from ten to twenty­five experts in the field, followed by a response from the paper’s authors.

Dr. Robert Cook’s Homepage Department of Psychology. This online resource has information for students on avian visual cognition, spatial cognition, and various societies and journals, including a list of experts in the field.

Krebs, J. R., and N. B. Davies, eds. 1997. Behavioural ecology: An evolutionary approach. 4th ed. Cambridge, MA: Blackwell. Defines behavioral ecology, discusses theory, and explains how predictions have been tested in experimental and comparative settings. The book is divided into three sections: mechanisms and individual behavior, from individual behavior to social systems, and life histories, phylogenies, and populations.

Lehrman, D. S. 1953. A critique of Konrad Lorenz’s theory of instinct. Quarterly Review of Biology 28:337–363. Lehrman raises several problems related to instinct theory: the problem of innateness and maturation of behavior; the problem of levels of organization within an individual; the problem of using the comparative method to study evolutionary levels of behavior; the problem of using physiological concepts in analyzing behavior.

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Sensory Perception

Sensory perception forms the foundation for how organisms experience their lives; Dusenbery 1992 notes that perceptual capacities differ between species, making it an interesting topic for comparative psychologists. Stebbins and Berkeley 1990 and Berkeley and Stebbins 1990 discuss the basic and complex mechanisms underlying perception in a variety of species. Understanding an organism’s perceptual capacity makes for a good starting point for determining appropriate test questions to explore the more cognitive or behavioral aspects of comparative psychology. Lazareva, et al. 2012 discusses the comparative behavior, biology, and evolution of vision.

Berkeley, M. A., and W. C. Stebbins. 1990. Comparative perception: Complex signals. New York: John Wiley. The second volume by these editors explores the perception of complex signals, covering both laboratory and field experiments. It includes information on electro­ and mechanoreception in fish, facial recognition, and acoustic serial pattern recognition. A section on communication further details understanding human speech and conspecific signals.

Dusenbery, D. B. 1992. Sensory ecology: How organisms acquire and respond to information. New York: W. H. Freeman. This text aims to understand how sensory perception allows organisms use information about their environment.

Lazareva, O. F., T. Shimizu, and E. A. Wasserman, eds. 2012. How animals see the world: Comparative behavior, biology, and evolution of vision. Oxford: Oxford Univ. Press. This text explores perceptual groupings and segmentations, object perception and recognition, motion perception, visual attention, and the evolution of vision.

Stebbins, W. C., and M. A. Berkeley. 1990. Comparative perception: Basic mechanisms. New York: John Wiley. The first volume by these editors is aimed at graduate level and above. The text covers the discrimination, localization, and development of many sensory modalities, including hearing, vision, taste, touch, and considers problems related to perception. A section on development includes studies on pre­verbal humans in addition to animal studies.

Attention

Attention is the selection of which stimulus to process, or of which process to execute. Zentall 2005 indicates that attention is highly associated with concentration, search behavior, and readiness to respond to certain stimuli. Washburn and Taglialatela 2006 suggest that though differences exist across studies, there are several generalizations that can be made about attention. Specific topics include, for instance, the debate surrounding the mechanism used during a visual search for cryptic prey. Guilford and Dawkins 1987 and Reid and Shettleworth 1992 cannot find evidence to distinguish between the search­image or search­ rate hypotheses, suggesting a different mechanism for attention priming.

Guilford, T., and M. S. Dawkins. 1987. Search images not proven: A reappraisal of recent evidence. Animal Behaviour 35.6: 1838–1845. The search­rate hypothesis, contrasting from the search­image hypothesis, predicts that adjusting search rate for one prey will http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 7/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies enhance searching for another prey, and that more cryptic prey require more search time. The authors re­analyze data from four studies and find that results cannot distinguish between search­image and search­rate hypotheses.

Reid, P. J., and S. J. Shettleworth. 1992. Detection of cryptic prey: Search image or search rate? Journal of Experimental Psychology: Animal Behavior Processes 18.3: 273. In this experimental study, pigeons searched for wheat, dyed to be conspicuous or cryptic against a background. Pigeons did not act according to the search­rate hypothesis or the search­image hypothesis. The authors suggest that search image be thought of as attention priming to distinct features of the item versus the background.

Washburn, D. A., and L. A. Taglialatela. 2006. Attention as it is manifest across species. In Comparative cognition: Experimental exploration of animal intelligence. Edited by E. A. Wasserman, and T. R. Zentall, 127–142. Oxford: Oxford Univ. Press. The authors identify seven generalizations about attention from the comparative literature.

Zentall, T. R. 2005. Selective and divided attention in animals. Behavioural Processes 69.1: 1–15. Animals learn not only which stimuli to attend to but also demonstrate dimensional learning of stimuli. In studies on search image, animals develop central representations of target items, and priming facilitates target detection. Animals must divide (or rapidly switch) attention between elements of compound stimuli.

Learning

How organisms learn is a topic of comparative psychology that has received much attention. Domjan 2014 and Thorpe 1956 cover many different learning processes, and Gallistel 1990 challenges traditional learning theory and proposes it be analyzed in a representational­computational framework. In non­associative learning, repeated exposure to a stimulus can cause a change in the strength of an individual’s response to the stimulus, either to react more strongly (sensitization) or to reduce its reaction (habituation). Associative learning is divided into classical and . Classical conditioning aims to pair an unconditioned stimulus that causes a reflexive response with a neutral conditioned stimulus; after repeated presentation, both the unconditioned and the conditioned stimulus should elicit the reflexive response. On the other hand, operant conditioning uses positive and negative reinforcement to change an association between an action and an outcome. Imprinting occurs during a time period in which the learner is sensitive to cues, for example, a bird learning who its mother is. Discrimination learning is a subset of associative learning in which subjects are required to differentiate between stimuli.

Domjan, M. 2014. The principles of learning and behavior. Stamford, CT: Cengage Learning. This textbook covers the basics of learning, from habituation, classical and instrumental conditioning, and stimulus control. The discussion surrounding the debate over the use of laboratory animals is appreciated.

Gallistel, C. R. 1990. The organization of learning. Cambridge, MA: MIT Press. This classic text challenges traditional associative learning theories and proposes that learning should be analyzed in a representational­computational framework. Gallistel examines experimental literature to determine how animals represent http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 8/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies space, time, number, and rate.

Thorpe, W. H. 1956. Learning and instinct in animals. Cambridge, MA: Harvard Univ. Press. Thorpe discusses the psychological and physiological processes of learning, including trial and error learning, and insight, and reviews the learning abilities of various animals.

Non­associative Learning

Non­associative learning refers to a change in the strength of a response to a repeated stimulus. When exposure to a repeated stimulus causes the diminution of a physiological or emotional response to it, it is known as habituation. Sensitization is the opposite process whereby the response increases with repeated stimulation.

Habituation and Sensitization

Kandel 1976 elegantly demonstrated the processes of habituation and sensitization in experiments with Aplysia californica. Thompson and Spencer 1966 and Groves and Thompson 1970 review the literature of the neurophysiological mechanisms of these processes and find evidence for two neural pathways. Rankin, et al. 2009 revises and adds to the characteristics of habituation. Thorpe 1956 discusses other types of learning such as latent learning and trial and error.

Groves, P. M., and R. F. Thompson. 1970. Habituation: A dual­process theory. 77.5: 419. The authors discuss behavioral plasticity in response to repeated stimulation and hypothesize that two independent processes (habituation and sensitization) develop in the central nervous system. Citing evidence from acute spinal cats and intact , the research finds different neuronal substrates for each response.

Kandel, E. R. 1976. Cellular basis of behavior, an introduction to behavioral neurobiology. W. H. Freeman. Kandel studied the non­associative learning processes of the Aplysia californica. His famous study on the gill and siphon withdrawal reflex in the mollusk showed that repeated stimulus presentation caused habituation of the reflex, but when a different stimulus was applied, the reflex became dishabituated; a stronger stimulus caused sensitization.

Rankin, C. H., T. Abrams, R. J. Barry, et al. 2009. Habituation revisited: An updated and revised description of the behavioral characteristics of habituation. Neurobiology of Learning and Memory 92.2: 135–138. This review offers an update to the two most­cited papers on habituation (Thompson and Spencer 1966, Groves and Thompson 1970) by revising the nine characteristics of habituation, and adding a tenth.

Thompson, R. F., and W. A. Spencer. 1966. Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Review 73.1: 16. The authors review literature on the neurophysiological mechanisms of habituation in the acute spinal cat.

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Thorpe, W. H. 1956. Learning and instinct in animals. Cambridge, MA: Harvard Univ. Press. Thorpe discusses the psychological and physiological processes of learning, including trial and error learning, latent learning and insight, and reviews the learning abilities of various animals.

Associative Learning

Associative learning is the process by which an individual learns to associate two stimuli, or the pairing of a stimulus with a behavioral response. In classical conditioning, an unconditioned stimulus that elicits a response is paired with a neutral stimulus. Following conditioning, the neutral (conditioned) stimulus should cause the behavioral response. Operant conditioning uses positive and negative reinforcement to shape behavior. In discrimination learning, subjects must learn to make different responses to different stimuli. Mackintosh 1983 distinguishes between classical and instrumental conditioning in his behavioral account of learning in animals.

Mackintosh, N. J. 1983. Conditioning and associative learning. Oxford: Clarendon. Covers many topics in learning, including classical and operant conditioning, positive and negative reinforcement, and associative and discrimination learning.

Classical (Pavlovian) Conditioning

Pavlov published decades of work in his 1927 manuscript in which he describes the process of conditioning reflexes in animals. Kehoe and Macrae 2002 review the history and methodology of classical conditioning. Osgood 1953 and Seidel 1959 debate over the interpretation of results in a stimulus­response framework versus a cognitive or representational one.

Kehoe, E. J., and M. Macrae. 2002. Fundamental behavioral methods and findings in classical conditioning. In A Neuroscientist’s Guide to Classical Conditioning. Edited by J. W. Moore, 171–231. New York: Springer. Covers the history of classical conditioning and the basic methods employed in experiments. The authors describe how a conditioned response can be transferred, lost, and recovered, and the variables that affect these processes. Finally, they discuss experiments with compound stimuli.

Osgood, C. E. 1953. Method and theory in experimental psychology. London: Oxford Univ. Press. Osgood covers many psychological processes and is cited here for his discussion of the controversy between the cognitive and stimulus­response theories, in which he argues that many psychological findings cannot be explained by simple stimulus­ response terms.

Pavlov, I. P. 1927. Conditioned reflexes: An investigation of the physiological activity of the cerebral cortex. London: Oxford Univ. Press. Pavlov describes twenty­five years of work in detail, including how he conditioned reflexes in animals, most famously, dogs salivating to the sound of a bell.

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Seidel, R. J. 1959. A review of sensory preconditioning. Psychological Bulletin 56.1: 58. Seidel argues that the classical definition of reinforcement is unnecessary for sensory preconditioning to be effective.

Operant (Instrumental) Conditioning

Operant, or instrumental, conditioning is a type of learning that associates reinforcers or punishments with certain behavior. Honig and Staddon 1977 describes basic and advanced principles and procedures in operant conditioning. Thorndike’s classic 1898 text describes different learning strategies that animals use in puzzle tasks. Staddon and Cerutti 2003 reviews literature on two types of operant behavior, interval timing and choice. Neuringer 2002 argues that variation itself can be an operant.

Honig, W. K., and J. E. R. Staddon, eds. 1977. Handbook of operant behavior. New York: Prentice Hall. This comprehensive and substantial text covers the basics of operant behavior and additionally discusses in detail topics such as autoshaping, stimulus contrast, and peak shift.

Neuringer, A. 2002. Operant variability: Evidence, functions, and theory. Psychonomic Bulletin & Review 9.4: 672–705. Neuringer argues that variation in response rate is due to reinforcers contingent on variability (i.e., that variation itself is an operant).

Staddon, J. E. R., and D. T. Cerutti. 2003. Operant behavior. Annual Review of Psychology 54:115–144. The authors review the literature on interval timing and choice, and discuss how linear waiting may be involved in both. They suggest a unified approach to future research.

Thorndike, E. L. 1898. Animal intelligence: An experimental study of the associative processes in animals. Monograph Supplements 2.4. New York and London: Macmillan. This is another classic text, describing the learning strategies that animals use when solving simple to intricate puzzle boxes, such as trial and error.

Sensitive Period and Imprinting

Many animals have a sensitive period for learning early in life; for example, Lorenz 1935 described birds imprinting on their mothers. Hess 1959 indicates that this early learning can affect social behavior later in life. Bolhuis 1991 demonstrates that imprinting can be overridden by other cues.

Bolhuis, J. J. 1991. Mechanisms of avian imprinting: A review. Biological Reviews 66.4: 303–345. Bolhuis reviews the literature on imprinting, in particular research showing that filial and sexual imprinting are reversible and can be overshadowed by other stimuli.

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Hess, E. H. 1959. Imprinting: An effect of early experience, imprinting determines later social behaviors in animals. Science 130.3368: 133–141. Hess reviews the literature on the sensitive period for early learning and imprinting.

Lorenz, K. 1935. Der kumpan in der umwelt des vogels. Journal of Ornithology 83.3: 289–413. Lorenz’s classical study on imprinting in greylag geese.

Discrimination Learning

Harlow 1949 and Harlow 1959 describe learning sets as “learning to learn,” that is, generalizing and transferring rules of discrimination to new tasks and inhibiting incorrect responses (error­factor theory). Mackintosh 1969 discusses discrimination learning in rats, birds, and fish. Rumbaugh, et al. 1998 proposes analyzing results with a transfer index, which is a ratio of correct answers on reversal trials to correct answers in the initial learning phase.

Harlow, H. F. 1949. The formation of learning sets. Psychological Review 56.1: 51. The development of a learning set is best understood as “learning to learn” the discriminations and performing better on each successive test. Brain­damaged monkeys developed sets more efficiently than normal monkeys, and Harlow discusses the implications.

Harlow, H. F. 1959. Learning set and error factor theory. Psychology: A study of a science 2:492–537. In addition to “learning to learn” discrimination sets, Harlow discusses how animals are able to learn in single trials by inhibiting incorrect behavior, the error­factor theory.

Mackintosh, N. J. 1969. Comparative studies of reversal and probability learning: Rats, birds and fish. In Animal discrimination learning. By N. J. Mackintosh, 137–162. New York: Academic. In discrimination learning, an animal must first learn a contingency such as “choose black over white,” and once this is sufficiently learned, the rules are flipped such that white becomes rewarded but not black. Subjects are measured on how quickly they can learn the new rule.

Rumbaugh, D. M., D. A. Washburn, and J. L. Pate. 1998. Discrimination learning set and transfer. In Comparative psychology: A handbook (Garland Reference Library of Social Science). Edited by G. Greenberg, and M. M. Haraway, 562– 565. New York: Taylor and Francis. The transfer index is the ratio of correct answers on reversal trials to answers in the pre­reversal learning period. Species with low encephalization quotients exhibited negative transfer, while species with higher encephalization performed better on transfer trials.

Concept Formation, Categorization http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 12/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies Concepts and categories let organisms organize information into functional groups, such as social relationships, perceptually similar items, and functionally similar items. While there is some evidence that animals can categorize basic perceptual (i.e., Herrnstein, et al. 1976 and Pepperberg 1990 are on the visual aspects) or functional (i.e., Zuberbuhler 2000 on vocalizations and Dasser 1988 on social relationships) items, there is mounting evidence, described in Smith, et al. 2004 that animals are less able than humans to understand more difficult classifications, especially higher­order categories such as same/different.

Dasser, V. 1988. A social concept in Java monkeys. Animal Behaviour 36.1: 225–230. Dasser demonstrates that Java monkeys form social categorizations and can correctly discriminate images of pairs of group mates based on affiliation, specifically mother­infant pairs versus unrelated pairs.

Herrnstein, R. J., D. H. Loveland, and C. Cable. 1976. Natural concepts in pigeons. Journal of Experimental Psychology: Animal Behavior Processes 2.4: 285. Pigeons were tested on three discrimination tasks of perceptual category. Pictures shown for the first time were discriminated almost as well as images from training.

Pepperberg, I. M. 1990. Some cognitive capacities of an African grey parrot (Psittacus erithacus). Advances in the Study of Behavior 19: 357–409. Pepperberg used a technique known as referential mapping to train a subject, , English words to describe and categorize objects. Results indicate that Alex can understand the concept of category and can correctly label items varying in shape, color, material, same/different, absence, and quantity.

Smith, J. D., J. P. Minda, and D. A. Washburn. 2004. Category learning in rhesus monkeys: A study of the Shepard, Hovland, and Jenkins (1961) tasks. Journal of Experimental Psychology: General 133.3: 398. A single stimulus set was assigned different types of categorization (shape, color, size) that increased in difficulty. Humans outperformed rhesus macaques, possibly due to humans’ ability to represent rule­based categories.

Zuberbuhler, K. 2000. Interspecies semantic communication in two forest . Proceedings of the Royal Society of London B 267: 713–718. In two playback experiments, Zuberbuhler demonstrates that Diana monkeys and Campbell’s monkeys understand each other’s alarm calls. This indicates that they are able to discriminate functional categories.

Memory

Memory, the formation, storage, and recovery of learned information, is essential for survival. In a comparison between pigeons, monkeys, and humans, Wright, et al. 1985 found that memory systems differ across species. Mettke­Hofmann and Gwinner 2003 suggests that memory systems are shaped by ecological pressures. Honig and Thompson 1982 differentiate between retrospective and prospective memory. Clayton and Dickinson 1998 established episodic memory (i.e., remembering the what, where, and when of an event, in scrub jays), but Suddendorf and Corballis 2007 claim that using a memory to prospectively plan for the future is less well documented. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 13/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies

Clayton, N. S., and A. Dickinson. 1998. Episodic­like memory during cache recovery by scrub jays. Nature 395.6699: 272– 274. Scrub jays recovered caches of perishable wax worms, a preferred food, after a short time interval, but after a longer interval they recovered caches of non­perishable peanuts. Results indicate that Scrub jays remember what, where, and when an item was cached, thus demonstrating episodic memory.

Honig, W. K., and R. K. Thompson. 1982. Retrospective and prospective processing in animal working memory. Psychology of Learning and Motivation 16:239–283. The authors differentiate retrospective memory (“looking back”) from prospective memory (“thinking ahead” to how to use learned information on future tasks). The same stimuli can cause both types of memory to be activated, depending on conditions.

Mettke­Hofmann, C., and E. Gwinner. 2003. Long­term memory for a life on the move. Proceedings of the National Academy of Sciences 100.10: 5863–5866. This study comparing migratory and non­migratory birds demonstrated that certain facets of memory are adapted to specific ecological conditions: migratory birds remembered feeding locations significantly longer than non­migratory birds.

Suddendorf, T., and M. C. Corballis. 2007. The evolution of foresight: What is mental time travel, and is it unique to humans? Behavioral and Brain Sciences 30.03: 299–313. This literature review does not find good evidence for mental time travel, in particular prospection (future planning), in nonhuman animals. They suggest that memory abilities differ in the degree of prospection that is possible and hypothesize a taxonomy of prospection.

Wright, A. A., H. C. Santiago, S. F. Sands, D. F. Kendrick, and R. G. Cook. 1985. Memory processing of serial lists by pigeons, monkeys, and people. Science 229.4710: 287–289. Three species were tested for their short­term memory recall of serial lists. Results indicated a serial position effect: at short intervals, the “recency” effect was evident; at longer intervals the primacy effect was evident. Items in the middle of the list were remembered in a U­shaped curve.

Physical Cognition

Physical cognition is a topic that encompasses spatial navigation, numerical understanding, and causal cognition, such as tool use. For example, in order to find food, an organism must locate it in space and time, choose between different quantities and qualities of food, and may need to extract the food from the environment using a tool. There may also exist a domain for numerical competence. Many tool­using species have some understanding of how their behavior impacts the world around them.

Spatial Cognition

http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 14/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies Whether traveling to the next food patch, emigrating to the neighboring community, or migrating long distance for a season, animals need to be able to navigate their environments effectively. To associatively learn the relationships between each destination would be cumbersome, and thus Healy 1998 argues that spatial learning is a different process, perhaps involving instinct. Cheng 1986 suggests that rats use a geometric module to navigate. O’Keefe and Nadel 1978 describes the role of the hippocampus in spatial navigation and that differences in the size of this brain region correlate with differences in spatial cognition. Morris’s classic 1984 water maze task demonstrates spatial learning in rats in a laboratory setting.

Cheng, K. 1986. A purely geometric module in the ’s spatial representation. Cognition 23.2: 149–178. Rats’ systematic errors in a working memory and a reference memory task lead the author to propose that they navigate using landmarks in a geometric module.

Healy, S., ed. 1998. Spatial representations in animals. Oxford and New York: Oxford Univ. Press. This edited volume discusses how animals navigate using landmarks, dead reckoning, spatial learning, and instinctual information. It includes a chapter on the neural bases of spatial representation.

Morris, R. 1984. Developments of a water­maze procedure for studying spatial learning in the rat. Journal of Neuroscience Methods 11.1: 47–60. The Morris water navigation task investigates spatial learning and working memory in rats. A rat is placed in a tank of water with a hidden submerged platform to find. With experience, rats are able to quickly locate the platform.

O’Keefe, J., and L. Nadel. 1978. The hippocampus as a cognitive map. Oxford: Clarendon. The authors propose that spatial learning is different from associative learning and synthesize evidence to show the role of the hippocampus not only in episodic memory retrieval but also more specifically in storing a cognitive map of features of a landscape.

Numerical Cognition

Exploring numerical cognition in non­verbal subjects holds interest to comparative psychologists because numbers are conceptual and there are at least two mechanisms involved in discriminating quantities: counting and subitizing. Counting, defined by Gelman and Gallistel 1978, involves three main principles: (1) a unique internal tag (“numeron”) is associated with each item; (2) tags are applied in the same order for each bout of counting; (3) the last tag in the set equals the number of items in the set. Subitizing, or the rapid, accurate perception of number, is adequate for up to six items, and discrimination ability decreases while reaction time increases as more items are added to a set. Capaldi and Miller 1988 discuss the mechanisms that rats use to count. Biro and Matsuzawa 2001 demonstrates that chimpanzees (for rhesus macaques, see Brannon and Terrace 1998) trained to understand Arabic numerals are able to order the numerals but have difficulty with the concept of zero.

Biro, D., and T. Matsuzawa. 2001. Use of numerical symbols by the chimpanzee (Pan troglodytes): Cardinals, ordinals, and the introduction of zero. Animal Cognition 4.3–4: 193–199. A chimpanzee with experience ordering numerals one through nine is introduced to “zero.” In three tasks, she was asked to demonstrate productive and receptive numeral use and to arrange them in ascending order. Her performance indicates that she http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 15/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies did not fully understand zero as the “absence of items.”

Brannon, E. M., and H. S. Terrace. 1998. Ordering of the numerosities 1 to 9 by monkeys. Science 282.5389: 746–749. Two rhesus monkeys were trained to order numerals one through four in ascending order, then tested on their responses to numerals five through nine, which they successfully ordered.

Capaldi, E. J., and D. J. Miller. 1988. Counting in rats: Its functional significance and the independent cognitive process that constitute it. Journal of Experimental Psychology: Animal Behavior Processes 14:3–17. Concluded that rats count reinforcing events, which is valuable for understanding instrumental learning. The authors rule out subitizing or simpler mechanisms because rats’ performance followed some of the principles of counting outlined by Gelman and Gallistel 1978.

Gelman, R., and C. R. Gallistel. 1978. The child’s understanding of number. Cambridge, MA: Harvard Univ. Press. This text challenges the prevailing notion that young children are cognitively incapable of understanding numbers, and the authors present research demonstrating at what age and the mechanisms by which children acquire numerical skills. In it, they define the principles of counting.

Understanding Physical Causation, Problem Solving

The ability to about physical problems in the environment is adaptive for survival, and some species demonstrate superior problem­solving skills in the physical domain, whether the goal is to acquire food or to avoid becoming food. Although this is debated, many argue that insight sometimes plays a role in solving physical problems, as does abstract reasoning and causal reasoning. One major area of research in physical cognition has involved tool use, and there is evidence spanning the animal kingdom.

Insight, Reason

Insight is the immediate learning of how to solve a task, without trial and error. Bräuer, et al. 2006 compares dogs’ and apes’ inferential reasoning abilities. Köhler 1925 studies on tool use in chimpanzees demonstrated an ambiguous result in which a subject joined two sticks to create one of sufficient length to rake in a food reward. Hanus, et al. 2011 tested three ape species on an insight task and suggests that functional fixedness might hinder creative problem solving. The authors of Seed and Boogert 2013 are skeptical that string­pulling tasks require insight, as subjects only succeed with certain feedback. Shettleworth 2012 offers several alternatives to insight as an explanation for behavior. Weir, et al. 2002 reports an example of insight in New Caledonian crows.

Bräuer, J., J. Kaminski, J. Riedel, J. Call, and M. Tomasello. 2006. Making inferences about the location of hidden food: Social dog, causal ape. Journal of Comparative Psychology 120.1: 38. Dogs and apes were tested on their ability to infer the location of hidden food based on cues provided by humans. Dogs were successful in using communicative cues (i.e., point) whereas apes were successful in using causal cues (i.e., shaken container with food makes noise).

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Hanus, D., N. Mendes, C. Tennie, and J. Call. 2011. Comparing the performances of apes (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus) and human children (Homo sapiens) in the floating peanut task. PloS one 6.6: e19555. In a follow­up study to the floating peanut task (Mendes, et al. 2007), the authors of the current study found that gorillas and orangutans failed to solve the task, and few chimpanzees succeeded. They suggest that functional fixedness might impair performance.

Köhler, W. 1925. The mentality of apes. Translated by E. Winter. London: Kegan Paul, Trench, Trubner. Köhler’s experiments with tool use in chimpanzees led to one of the most recognizable examples of insight in animals, when a chimpanzee connected two sticks to create a longer one, to rake in food that was out of reach.

Mendes, N., D. Hanus, and J. Call. 2007. Raising the level: Orangutans use water as a tool. Biology letters 3.5: 453–455. This study replicates the Aesop fable in which a tube must be filled with water to reach a floating food reward, and provides good evidence of insightful behavior.

Seed, A. M., and N. J. Boogert. 2013. Animal cognition: An end to insight? Current Biology 23.2: R67–R69. The authors argue that the studies of corvids and apes pulling string to obtain a reward does not require insight to solve the task, as the subjects are only successful when they have perceptual­motor feedback, such as seeing the reward move closer.

Shettleworth, S. J. 2012. Do animals have insight, and what is insight anyway? Canadian Journal of Experimental Psychology/Revue canadienne de psychologie expérimentale 66.4: 217. Shettleworth reviews the literature on human insight and the history of studies on animal insight. She discusses several processes that could take place instead of insight: multiple controlling stimuli, changing dynamics, functional generalization, automatic chaining, and resurgence.

Weir, A. A., J. Chappell, and A. Kacelnik. 2002. of hooks in New Caledonian crows. Science 297.5583: 981. A New Caledonian crow bent a piece of straight wire into a hook, in order to lift a bucket out of a tube. This example of insight and perhaps of causal understanding leads the authors to suggest that some corvids may rival primates in cognitive capacities.

Tool Use

Shumaker, et al. 2011 writes a comprehensive textbook on tool use in animals. Fragaszy, et al. 2004 reports stone tool use in wild capuchin monkeys. Finn, et al. 2009 reports an octopus using coconut shells for defense. There is a long history of observing tool use in wild chimpanzees, and Sanz and Morgan 2007 reports the use of a tool set (i.e., multiple tools to access a termite mound).

Finn, J. K., T. Tregenza, and M. D. Norman. 2009. Defensive tool use in a coconut­carrying octopus. Current Biology 19.23: R1069–R1070. The authors observed Amphioctopus marginatus carrying coconut shell halves up to twenty meters in order to use as shelter. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 17/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies This is the first reported example of flexible tool use in an invertebrate.

Fragaszy, D., P. Izar, E. Visalberghi, E. B. Ottoni, and M. G. de Oliveira. 2004. Wild capuchin monkeys (Cebus libidinosus) use anvils and stone pounding tools. American Journal of Primatology 64.4: 359–366. This research offers evidence that stone tool use is not limited to great apes in the lineage: capuchin monkeys routinely use stones and anvils to crack open palm nuts.

Sanz, C. M., and D. B. Morgan. 2007. Chimpanzee tool technology in the Goualougo Triangle, Republic of Congo. Journal of Human Evolution 52.4: 420–433. The authors report chimpanzees’ use of three tool sets ranging from simple tasks to hierarchical sequences, indicating a degree of complexity not seen in other populations.

Shumaker, R. W., K. R. Walkup, and B. B. Beck. 2011. Animal tool behavior: The use and manufacture of tools by animals. Johns Hopkins Univ. Press. In this updated version of the 1980 original, there are three times as many examples of animal tool use, ranging from insects, invertebrates, fish, birds, to mammals, including several chapters dedicated to primates.

Social Cognition

Social living is beneficial for many . Individuals can share information regarding the location of food or predators and can help share the burden of raising offspring, to name a few. There are also costs, including competition for food and/or mating opportunities and aggression. Animals can acquire new skills from each other through social learning; when these behaviors are transmitted through generations, they can become cumulative culture. A key aspect of social life is the ability to communicate, and may involve rudimentary traits of human language, such as syntax and referentiality. Evidence that animals cooperate has triggered recent explorations into prosociality.

Social Learning

Galef and Laland 2005 find that individuals can learn from others socially, rather than risking the time or consequences of trial and error learning; for example, Mineka and Cook 1988 demonstrates that naïve monkeys learn to fear snakes by observing wild­reared monkeys. Zentall and Galef 2013 discuss the many mechanisms of social learning, including enhancement, facilitation, emulation, and . Critically important for social learning is the presence of a social agent; when Hopper 2010 demonstrated the mechanics of a task without an agent, animal subjects were often unable to emulate or imitate the goals of the task.

Galef, B. G., and K. N. Laland. 2005. Social learning in animals: Empirical studies and theoretical models. Bioscience 55.6: 489–499. Reviews the impact of social learning on behaviors such as feeding/foraging, tool use, predator avoidance, and mate choice. They cover models of when to copy behavior (i.e., when individual learning is costly) and who to copy (i.e., a successful individual). http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 18/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies

Hopper, L. M. 2010. “Ghost” experiments and the dissection of social learning in humans and animals. Biological Reviews 85.4: 685–701. A ghost display shows a test subject how an apparatus works, without an agent acting upon it, whereas an end­state display shows the state of the apparatus before and after its use but not during. Hopper calls for clarity in identifying social learning mechanisms.

Mineka, S., and M. Cook. 1988. Social learning and the acquisition of snake fear in monkeys. In Zentall, T. R., and B. G. Galef Jr., eds. Social learning: Psychological and biological perspectives, 51–73. This is a classic study demonstrating that laboratory primates with no prior experience with snakes learned to fear them from watching the fear responses of wild­reared primates.

Zentall, T. R., and B. G. Galef Jr., eds. 2013. Social learning: Psychological and biological perspectives. New York: Psychology Press. Covers the theoretical and methodological issues of studying social learning in animals, with sections on avoidance learning, foraging and feeding, arbitrary responses, and communication.

Traditions and Cumulative Culture

Fragaszy and Perry 2008 describe how socially transmitted behaviors become traditions. Whiten and Mesoudi 2008 take this one step further and suggest that when these cultural behaviors are transmitted through generations or improved upon, they can be seen as cumulative culture. Tennie, et al. 2009 argue that chimpanzee culture may not be marked by social learning as much as had been assumed, and that human culture is unique in that subsequent generations add to and improve upon prior innovations, without loss of technique (e.g., ratcheting). Krützen, et al. 2005 and Whiten, et al. 1999 show observational and experimental evidence of traditions and culture in animals.

Fragaszy, D. M., and S. Perry, eds. 2008. The biology of traditions: Models and evidence. Cambridge, UK: Cambridge Univ. Press. Contributions to this volume discuss social learning, culture, and traditions in non­human species from a biological perspective; that is, traditions are treated as biological phenomena that can be compared just as any other biological trait.

Krützen, M., J. Mann, M. R. Heithaus, R. C. Connor, L. Bejder, and W. B. Sherwin. 2005. Cultural transmission of tool use in bottlenose . Proceedings of the National Academy of Sciences of the United States of America 102.25: 8939– 8943. The authors rule out genetic or ecological explanations for cetacean material culture. They argue that the most parsimonious explanation for sponging tool use in dolphins is through social learning, more specifically, transmission through matrilines.

Tennie, C., J. Call, and M. Tomasello. 2009. Ratcheting up the ratchet: On the evolution of cumulative culture. Philosophical Transactions of the Royal Society B: Biological Sciences 364.1528: 2405–2415. The authors argue that chimpanzee cultural traditions may be due to product­oriented rather than process­oriented copying. On http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 19/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies the other hand, human cultural traditions accumulate improvements over time.

Whiten, A., J. Goodall, W. C. McGrew, T. Nishida, V. Reynolds, Y. Sugiyama, C. E. G. Tutin, R. W. Wrangham, and C. Boesch. 1999. Cultures in chimpanzees. Nature 399.6737: 682–685. This publication represents a milestone in the literature on chimpanzee culture. The authors analyze the presence, absence, and variation in thirty­eight potential cultural traits among six long­term African field sites, and rule out genetic and ecological explanations for the differences in behavior and complexity.

Whiten, A., and A. Mesoudi. 2008. Establishing an experimental science of culture: Animal social diffusion experiments. Philosophical Transactions of the Royal Society B: Biological Sciences 363.1509: 3477–3488. The authors review thirty­three papers on cultural diffusion experiments in animals and distinguish between different methodologies. They suggest that humans’ capacity for complex culture originates from a biological base, as many animals socially transmit information and learn novel behavior from conspecifics.

Communication/Language Comprehension and Production

Bradbury and Vehrencamp 1998 discuss the basic principles of animal communication in various modalities. Seyfarth, et al. 1980 and Janik, et al. 2006 argue that animal communication contains some rudimentary aspects of human language, such as referentiality. Many decades of research have been dedicated to studying humanlike symbolic language in birds (e.g., Pepperberg 2009) and great apes (e.g., Gardner, et al. 1989 and Savage­Rumbaugh 1986) and results have implications for the evolution of language in humans.

Bradbury, J. W., and S. L. Vehrencamp. 1998. Principles of animal communication. Sunderland, MA: Sinauer Associates. This undergraduate­level textbook aims to cover principles of communication across taxa and modalities, including visual, auditory, chemical, and tactile.

Gardner, R. A., B. T. Gardner, and T. E. Van Cantfort, eds. 1989. Teaching sign language to chimpanzees. New York: State Univ. of New York Press. This book details the story of teaching American Sign Language to chimpanzees (Pan troglodytes). One particularly fascinating element is that taught signs to her adopted son, .

Janik, V. M., L. S. Sayigh, and R. S. Wells. 2006. Signature whistle shape conveys identity information to bottlenose dolphins. Proceedings of the National Academy of Sciences 103.21: 8293–8297. The authors removed characteristics of dolphins’ whistles and performed a playback experiment. The results indicate that dolphins can recognize identity information from these calls, opening the possibility for more research into whether dolphins’ signals are referential.

Pepperberg, I. M. 2009. The Alex studies: Cognitive and communicative abilities of grey parrots. Boston: Harvard Univ. Press. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 20/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies Alex the parrot had a vocabulary of 100 words, could identify fifty objects, count up to six, and discriminate seven colors and five shapes. His ability to correctly categorize novel items based on all of these parameters indicated that he reasoned about categories, qualities, and quantities, rather than repeating conditioned words.

Savage­Rumbaugh, E. S. 1986. Ape language: From conditioned response to symbol. New York: Columbia Univ. Press. Presents the systematic account of how advanced symbolic language skills were taught to two chimpanzees and a bonobo. Their linguistic ability has implications for the fields of linguistics, psychology, anthropology, and the evolution of human language.

Seyfarth, R. M., D. L. Cheney, and P. Marler. 1980. Vervet monkey alarm calls: Semantic communication in a free­ranging primate. Animal Behaviour 28.4: 1070–1094. In this landmark playback experiment, it is shown that vervet monkeys use referential communication to warn others of the presence of predators.

Cooperation

Dugatkin 1997 reviews many examples of cooperation in the animal kingdom, and Boesch 1994 focuses on examples in primates. While initially work focused on understanding how cooperation could evolve through natural selection, new work more relevant to the interests of comparative psychologists focuses on the mechanisms underpinning cooperation: Brosnan and de Waal 2014 report on inequity aversion and how it may have evolved in conjunction with cooperation. Melis, et al. 2006 demonstrate that tolerant pairs of chimpanzees are more likely to cooperate. Jensen 2010 discusses punishment and spite as enforcement mechanisms of cooperation. Rutte and Taborsky 2008 describe the influence of social behavior on cooperation, and Brosnan and Bshary 2010 discuss the role of cognition in cooperation.

Boesch, C. 1994. Cooperative hunting in wild chimpanzees. Animal Behavior 48:653–667. This paper demonstrated that group hunting was an evolutionarily stable strategy for chimpanzees in Tai Forest, whereas a high success rate for solitary hunters meant that this was not the case among Gombe chimpanzees. This paper was notable for considering how ecological and social differences could lead to different behaviors.

Brosnan, S. F., and R. Bshary. 2010. Theme issue “Cooperation and deception: From evolution to mechanisms.” Philosophical Transactions of the Royal Society B: Biological Sciences 365.1553: 2591–2764. This issue of Philosophical Transactions contains a series of papers exploring the mechanisms underlying cooperation and deception across the animal kingdom. Papers focus on empirical evidence, modeling, and theory.

Brosnan, S. F., and F. B. M. de Waal. 2014. Evolution of responses to (un)fairness. Science 346.6207. The authors argue that the sense of fairness evolved in conjunction with cooperation. Many animals recognize when they get a lower value food reward than does a partner, helping them to recognize when to find a new partner. Apes and humans also recognize when they get more and can proactively avoid inequity responses by partners to maintain beneficial cooperative relationships.

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Dugatkin, L. A. 1997. Cooperation among animals: An evolutionary perspective. Oxford Series in Ecology and Evolution. New York: Oxford Univ. Press. This landmark volume considered the evolution of cooperation across all animal taxa and is still a key text in the field.

Jensen, K. 2010. Punishment and spite, the dark side of cooperation. Philosophical Transactions of the Royal Society B: Biological Sciences 365:2635–2650. Jensen reviews the literature on second­ and third­party punishment and spite, and discusses underlying .

Melis, A. P., B. Hare, and M. Tomasello. 2006. Engineering cooperation in chimpanzees: Tolerance constraints on cooperation. Animal Behaviour 72.2: 275–286. Chimpanzee pairs that were likely to share food outside of testing scenarios were more likely to cooperate spontaneously to pull in a tray with food.

Rutte, C., and M. Taborsky. 2008. The influence of social experience on cooperative behavior of rats (Rattus norvegicus): Direct vs generalized reciprocity. Behavioral Ecology and Sociobiology 62:499–505. This paper follows up on the team’s previous finding of generalized reciprocity in rats, demonstrating that although rats do show generalized reciprocity, direct reciprocity is stronger than generalized.

Prosocial Behavior and Empathy

Although both Charles Darwin and Adam Smith assumed empathy (what they called sympathy) in species besides humans, the movement against anthropomorphism and in favor of avoiding complex psychological process as explanations led to this topic being avoided until the early 21st century. New observations and experiments show that prosocial behavior and empathy may exist in species other than humans in some species or contexts: Burkart, et al. 2007 describe food provisioning in common marmosets, but Silk, et al. 2005 describe chimpanzees’ indifference to sharing food with others. Preston and de Waal 2002 define the perception­action model of empathy, which includes basic emotional contagion processes as well as what most consider true empathy and therefore allows for a rigorous approach to “basic” levels of empathy that may be present in other species. Ben­Ami Bartal, et al. 2011 show that rats will respond to distress in a conspecific, but Silberberg, et al. 2014 criticize the results of that study and interpret them differently. Experiments have shown that prosocial behavior and empathy are contextual and depend on genetics (e.g., Chen, et al. 2009), communication, and reward values (e.g., Silk, et al. 2005, Cronin 2012).

Ben­Ami Bartal, I., J. Decety, and P. Mason. 2011. Empathy and pro­social behavior in rats. Science 334:1427–1430. Although there had been reports of rats behaving altruistically as early as the 1960s, this paper provided the first systematic evidence that rats would respond to a conspecific in distress. The authors argue that this is evidence for the deep biological roots of helping behavior in the animal kingdom.

Burkart, J., E. Fehr, C. Efferson, and C. P. van Schaik. 2007. Other­regarding preferences in a non­human primate: Common marmosets provision food altruistically. Proceedings of the National Academy of Sciences 104.50: 19762– http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 22/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies 19766. Demonstrated that unlike chimpanzees (see Silk, et al. 2005, below), cooperatively breeding marmosets preferred an option that fed both themselves and a partner (their pair mate) over options that fed only themselves. The authors argue that this is support for the cooperative breeding hypothesis.

Chen, Q., J. B. Panksepp, and G. P. Lahvis. 2009. Empathy is moderated by genetic background in mice. PLoS ONE 4.2: e4387. The authors found that the genetic background of the mice predicted their response to the social distress of other mice.

Cronin, K. A. 2012. Prosocial behaviour in animals: The influence of social relationships, communication and rewards. Animal Behaviour 84.5: 1085–1093. Even though most papers have focused on the evolution of prosocial behavior, this review focuses on what is known about how the context influences prosocial behavior. Although most of the papers to the date of the review involved non­human primates, what was known about other species was included in this review.

Preston, S. D., and F. de Waal. 2002. Empathy: Its ultimate and proximate bases. Behavioral and Brain Sciences 25.01: 1– 20. This landmark paper proposed a new model of empathy, the Perception­Action Model, which integrated the disparate views of what empathy was and what it entailed. They argue for a broad construal of empathy that includes everything from simple process such as emotional contagion to complex ones such as “true empathy.”

Silberberg, A., C. Allouch, S. Sandfort, D. Kearns, H. Karpel, and B. Slotnick. 2014. Desire for social contact, not empathy, may explain “rescue” behavior in rats. Animal Cognition 17.3: 609–618. The authors criticize the conclusions of Ben­Ami Bartal, et al. 2011 and suggest that rather than empathy, rats act to free trapped conspecifics due to neophobia and desire for social contact.

Silk, J. B., S. F. Brosnan, J. Vonk, et al. 2005. Chimpanzees are indifferent to the welfare of unrelated group members. Nature 437.7063: 1357–1359. Provided the first test of whether non­human primates, in this case chimpanzees, would prefer options that fed both themselves and a social partner to options that fed only themselves. Chimpanzees did not behave prosocially, sparking other studies to pin down the presence or absence of prosocial behavior.

Mental Representations

The question of whether animals have mental representations similar to humans’ has influenced research from problem solving and tool use, to memory, and to social interactions. It is often presumed that one must have a sense of self in order to have representations about things outside the self. How animals respond to mirrors may help to answer the question of self­ awareness. If an animal is self­aware, it may be able to think about its own thoughts (i.e., it possesses metacognition). Whether animals can think about and attribute representations or psychological states to others is known as “theory of mind.” Tactical http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 23/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies deception is often a good place to look for animals’ understanding of others’ mental states.

Mirror Self­Recognition

Gallup 1970 first asked whether chimpanzees are self­aware and developed a task to determine whether they are able to recognize themselves in mirrors. This test has been repeated with elephants (e.g., Plotnik, et al. 2006) and dolphins (see Reiss and Marino 2001). Anderson 1984 reviews the developmental literature on mirror self­recognition in humans. Contributions to Parker, et al. 1994 debate the underlying abilities supporting self­recognition.

Anderson, J. R. 1984. The development of self­recognition: A review. Developmental Psychobiology 17.1: 35–49. Anderson reviews the literature on the development of mirror self­recognition and other related behaviors in humans.

Gallup, G. G. 1970. Chimpanzees: Self­recognition. Science 167.3914: 86–87. Gallup anesthetized and painted a small dot on the foreheads and ears of adolescent chimpanzees. Subjects subsequently touched the painted areas four to ten times more frequently with the mirror than without it, suggesting that chimpanzees have self­recognition, and may be self­aware.

Parker, S. T. E., R. W. Mitchell, and M. L. Boccia, eds. 1994. Self­awareness in animals and humans: Developmental perspectives. New York: Cambridge Univ. Press. The contributors discuss competing theories to explain self­awareness from a developmental and comparative perspective.

Plotnik, J. M., F. B. de Waal, and D. Reiss. 2006. Self­recognition in an Asian elephant. Proceedings of the National Academy of Sciences 103.45: 17053–17057. Three Asian elephants (Elephas maximus) were marked with visible and invisible paint and then exposed to a mirror. Their responses, which were similar to those of apes and dolphins, suggest convergent cognitive evolution.

Reiss, D., and L. Marino. 2001. Mirror self­recognition in the bottlenose : A case of cognitive convergence. Proceedings of the National Academy of Sciences 98.10: 5937–5942. The authors present evidence that two dolphins react to mirrors similarly to apes, indicating some degree of self­awareness.

Metacognition

Beran, et al. 2012 provide a comprehensive summary of what is known about metacognition in animals and humans. Metacognition, or the ability to monitor one’s own cognition and decision making, is difficult to assess in non­verbal subjects, but clever experimental designs from Hampton 2001 and Browne 2004, have allowed insight into this process in non­human species. Smith 2009 reviews the literature and discusses alternative explanations, methodological changes to address these concerns, and directions for future research.

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Beran, M. J., J. Brandl, J. Perner, and J. Proust, eds. 2012. Foundations of metacognition. Oxford: Oxford Univ. Press. With contributions from experts in the field, this volume discusses metacognition in animals and humans, and the function of metacognition.

Browne, D. 2004. Do dolphins know their own ? Biology and Philosophy 19.4: 633–653. Browne discusses the difficulty in interpreting potential metacognition in a dolphin; he weighs inflationary and deflationary explanations of observed behavior, as well as a functional concept of metacognition.

Hampton, R. R. 2001. Rhesus monkeys know when they remember. Proceedings of the National Academy of Sciences 98.9: 5359–5362. In the first empirical demonstration of metacognition in non­humans, Hampton asks whether rhesus monkeys can report the presence or absence of a memory. Subjects improved accuracy on memory tests when they had the option to decline when they had forgotten.

Smith, J. D. 2009. The study of animal metacognition. Trends in Cognitive Sciences 13.9: 389–396. Smith reviews the literature of comparative metacognition, which is the ability to monitor one’s own cognition. He discusses theoretical concerns and how new paradigms have mostly overcome them. At the end he outlines several suggestions for continuing research in this area.

Theory of Mind

Premack and Woodruff 1978 questioned whether chimpanzees can reason about the mental states of others, that is, whether they have a predictive theory about minds. Since then, debate has continued over to what degree any non­human possesses theory­of­mind type capacities. Although most scholars agree that only humans possess full theory of mind, Call and Tomasello 2008 argue that chimpanzees do have several underlying capacities, including understanding others’ perceptual states, knowledge, goals, and intentions. Evidence from chimpanzees (see Hare, et al. 2001), and corvids (Bugnyar 2007), support these claims. On the other hand, Heyes 1998 argues that there is no evidence for this type of understanding. Carruthers and Smith 1996 collected contributions on the developmental aspects of theory of mind in humans, developmentally disabled humans, and non­humans. Wimmer and Perner 1983 conclude that there is a developmental arc in theory­of­mind capacity in humans, Baron­Cohen 1997 describes certain deficits in people on the autism spectrum, and Yirmiya, et al. 1998 compares abilities between normally developing humans, those with mental deficits such as Down syndrome, and those on the autistic spectrum.

Baron­Cohen, S. 1997. Mindblindness: An essay on autism and theory of mind. Cambridge, MA: MIT Press. Baron­Cohen argues that children on the autism spectrum have a selective impairment in their ability to understand the mental states of others, an ability that otherwise develops naturally and fully by about four years of age.

Bugnyar, T. 2007. An integrative approach to the study of “theory­of­mind”­like abilities in ravens. Japanese Journal of Animal Psychology 57.1: 15–27. http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 25/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies Bugnyar discusses studies on Corvus corax in the guesser­knower paradigm, and whether their performance is affected by manipulated cues, how skills develop in ontogeny, and how flexibly these skills can be applied.

Call, J., and M. Tomasello. 2008. Does the chimpanzee have a theory of mind? 30 years later. Trends in Cognitive Sciences 12.5: 187–192. The authors review thirty years of research on chimpanzee theory of mind and include evidence that chimpanzees understand others’ perceptual states, knowledge, goals, and intentions, but do not find evidence for their false belief understanding.

Carruthers, P., and P. K. Smith, eds. 1996. Theories of theories of mind. Cambridge, UK: Cambridge Univ. Press. This collection of contributions from psychologists, primatologists, and philosophers tackles the questions of how individuals understand the thoughts, intentions, and desires of others.

Hare, B., J. Call, and M. Tomasello. 2001. Do chimpanzees know what conspecifics know? Animal Behaviour 61.1: 139– 151. Subordinate chimpanzees competed with a dominant individual over food items that were visible to subordinates but may or may not have been seen by dominants in their final hiding location. Subordinate’s behavior indicates that they knew what dominants had seen during baiting.

Heyes, C. M. 1998. Theory of mind in nonhuman primates. Behavioral and Brain Sciences 21.01: 101–114. Heyes critiques work on theory of mind in primates, instead arguing that most behavior can be explained by associative learning or making inferences based on non­mental categories. Heyes offers a new experimental paradigm to test for chimpanzees’ understanding of the concept “to see.”

Premack, D., and G. Woodruff. 1978. Does the chimpanzee have a theory of mind? Behavioral and Brain Sciences 1.4: 515–526. Premack and Woodruff coin the term “theory of mind” to ask whether chimpanzees have a prediction­generating theory of the internal mental states of others. One chimpanzee subject, Sarah, was able to predict what a human actor would do to solve various problems, indicating rudimentary theory­of­mind abilities.

Wimmer, H., and J. Perner. 1983. Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children’s understanding of deception. Cognition 13.1: 103–128. Children aged three to nine years were tested on their understanding and attribution of false belief to others. Children answered correctly more often with increasing age.

Yirmiya, N., O. Erel, M. Shaked, and D. Solomonica­Levi. 1998. Meta­analyses comparing theory of mind abilities of individuals with autism, individuals with mental retardation, and normally developing individuals. Psychological Bulletin 124.3: 283. The authors perform three meta­analyses on theory of mind abilities in normally developing humans, those with mental deficits http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 26/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies such as Down syndrome, and those on the autism spectrum. They emphasize considering the etiologies of various subject groups as a moderator variable.

Machiavellian Intelligence, Deception

Humphrey 1976 argues that problem solving is not only in the physical but also the social domain. Byrne and Whiten 1988 takes this one step further and argues that it would be advantageous for individuals to be able to predict the behavior of others in order to out­compete them; this is the essence of Machiavellian intelligence. Tactical deception is a prime example of out­competing others, and Byrne and Whiten 1990 collated a database of examples in primates. Brown, et al. 2012 describes a fascinating example in cuttlefish.

Brown, C., M. P. Garwood, and J. E. Williamson. 2012. It pays to cheat: Tactical deception in a cephalopod social signalling system. Biology Letters 8.5: 729–732. Reports that male cuttlefish employ a deceptive courtship display, altering their skin pigmentation to appear “female” and thus non­threatening on their side facing the rival male, while displaying courtship coloration toward a receptive female.

Byrne, R. W. and A. Whiten. 1988. Machiavellian intelligence: Social expertise and the evolution of intellect in monkeys, apes, and humans. Oxford: Oxford Univ. Press. This book collates twenty­five articles that argue that human and non­human primate intelligence stems from the social world, rather than from the realm of tool use. Individuals in social groups need to outwit each other for access to resources, thus creating an evolutionary arms race toward more advanced social cognition.

Byrne, R. W. and A. Whiten. 1990. Tactical deception in primates: The 1990 database. Primate Report 27:1–101. In a survey of primatologists, Byrne and Whiten categorize hundreds of examples of tactical deception, that is, when an agent behaves in a way that is misconstrued by another and is to the agent’s advantage. They argue that tactical deception is a good place to look for second­order intentionality.

Humphrey, N. K. 1976. The social function of intellect. In Growing points in ethology. Edited by P. P. G. Bateson, and R. A. Hinde, 303–317. Oxford: Cambridge Univ. Press. Humphrey writes that the capacity for problem solving extends to the social domain and that primate intelligence is an adaptation to complex social living, including the ability to predict the behavior of others, so as to outmaneuver them.

Personality

Recent explorations into animal personality reveal consistent individual differences in behavior based on certain measurable behavioral dimensions. Gosling and John 1999 review personality factors from twelve species. Stamps and Groothuis 2010 advocate using contextual reaction norms to study the development of animal personality. Freeman, et al. 2013 identify five personality factors in chimpanzees. Morton, et al. 2013 indicate that differences in personality may affect differences in subject participation and performance on tasks, and warn that this must be taken into consideration in behavioral studies.

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Freeman, H. D., S. F. Brosnan, L. M. Hopper, S. P. Lambeth, S. J. Schapiro, and S. D. Gosling. 2013. Developing a comprehensive and comparative questionnaire for measuring personality in chimpanzees using a simultaneous top‐ down/bottom‐up design. American Journal of Primatology 75.10: 1042–1053. By combining top­down and bottom­up approaches to rating personality in chimpanzees, this study found five reliable factors: /undependability, dominance, openness, extraversion, and agreeableness, and provisional evidence for a sixth, methodical.

Gosling, S. D., and O. P. John. 1999. Personality dimensions in nonhuman animals a cross­species review. Current Directions in Psychological Science 8.3: 69–75. The authors review nineteen studies of personality factors in twelve non­human species to offer a new perspective on human personality research.

Morton, F. B., P. C. Lee, and H. M. Buchanan­Smith. 2013. Taking personality selection bias seriously in animal cognition research: A in capuchin monkeys (Sapajus apella). Animal cognition 16.4: 677–684. Cautions behavioral researchers to acknowledge personality­based selection bias involved in studies (i.e., that animals that are more open and less assertive are more likely to participate and perform well in other studies).

Stamps, J., and T. G. Groothuis. 2010. The development of animal personality: Relevance, concepts and perspectives. Biological Reviews 85.2: 301–325. The authors provide a framework for the study of personality and focus on contextual generality, temporal consistency, and the effect of genes and experience.

Contextual Influences on Decision Making

Decision making can vary on many dimensions. Kahneman and Tversky 1979 describe that humans have many cognitive and behavioral biases that influence decision making. Some of these biases have recently been demonstrated in non­human primates, indicating an evolutionary basis: Brosnan, et al. 2007 describe the endowment effect in chimpanzees; Hayden, et al. 2010 provide evidence of ambiguity aversion in rhesus macaques; and Proctor, et al. 2014 discuss biases in a gambling task for humans, chimpanzees, and capuchin monkeys. Aside from these biases, decision­making can also be affected by a number of other factors, such as stress, environment, body condition. Bachman 1993, and notably, Latty and Beekman 2010 demonstrate that advanced cognition is not required to exhibit these decision­making biases.

Bachman, G. C. 1993. The effect of body condition on the trade­off between vigilance and foraging in Belding’s ground squirrels. Animal Behaviour 46.2: 233–244. This playback experiment demonstrates that foraging squirrels with lower body mass are less vigilant after hearing alarm calls, indicating a tipping point between foraging and vigilance decisions, based on body mass.

Brosnan, S. F., O. D. Jones, S. P. Lambeth, M. C. Mareno, A. S. Richardson, and S. J. Schapiro. 2007. Endowment effects in http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 28/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies chimpanzees. Current Biology 17.19: 1704–1707. This was the first paper to show that species other than humans are biased to keep objects already in their possession rather than trading them for more preferred objects, a bias called the endowment effect. Its presence in other species indicates that it is not just a result of culture or procedures during testing in humans.

Hayden, B. Y., S. R. Heilbronner, and M. L. Platt. 2010. Ambiguity aversion in rhesus macaques. Frontiers in Neuroscience 4.166: 1–7. Humans prefer risky options over those that are ambiguous, and this paper shows that rhesus monkeys show the same bias. These data support the general finding that cognitive and behavioral biases are widespread in animals and therefore are not the result of unique human factors.

Kahneman, D., and A. Tversky. 1979. Prospect theory: An analysis of decision under risk. Econometrica: Journal of the Econometric Society 47.2: 263–291. The authors explain irrational decision making in humans in the face of risk: for instance, in certain contexts humans are risk averse to gains, and risk prone to losses.

Latty, T., and M. Beekman. 2010. Irrational decision­making in an amoeboid organism: Transitivity and context­dependent preferences. Proceedings of the Royal Society B: Biological Sciences 278.1703: 307–312. Decision making may deviate from rational decision making based on absolute outcomes when subjects experience framing, such as when preferences switch when an additional item is added to the set. The authors show that this comparative valuation rule holds in amoeba, indicating that decision­making biases exist even in the absence of brains.

Proctor, D., R. A. Williamson, R. D. Latzman, F. B. Waal, and S. F. Brosnan. 2014. Gambling primates: Reactions to a modified Iowa Gambling Task in humans, chimpanzees and capuchin monkeys. Animal Cognition 17.4: 983–995. Capuchin monkeys and chimpanzees show decision­making biases in the Iowa Gambling Task, in an expanded procedure designed to distinguish variance avoidance from reward maximization. Although all three species looked similar in the traditional task, when variance and reward maximization were separated species differences emerged, indicating the importance of disentangling competing motivations.

Evolution of the Field

Historically some topics of comparative psychology have been discouraged, due to concerns with anthropomorphism or over­ interpretation (e.g., empathy, , metacognition, or personality, all discussed above. As such topics are being revisited, new methods and evidence are now allowing these once­discarded ideas to emerge as flourishing fields of study, with overlaps in other disciplines, such as neuroscience and economics. As comparative psychology expands to include questions and techniques from other fields, and as new questions are developed, this phenomenon will continue. Furthermore, research efforts have transitioned from answering the all­encompassing questions, such as “do (or don’t) chimpanzees have theory of mind?” to more nuanced investigations of certain capacities associated with these big­picture ideas, such as whether chimpanzees understand the visual perspective of others. These focused, data­driven questions on underlying mechanisms are legitimizing the scientific study of these ideas that were once considered anthropomorphic and intractable to empirical investigation. As more evidence accumulates from multiple species tested using ecologically valid methods, comparative http://www.oxfordbibliographies.com/view/document/obo­9780199828340/obo­9780199828340­0176.xml?print 29/30 10/28/2015 Comparative Psychology ­ Psychology ­ Oxford Bibliographies psychologists can hope to gain perspective on these broader ideas. While much focus has been placed on cognitive continuity between species, Vonk and Shackelford 2012 has placed (re­)emphasis on the ecological and evolutionary context of behavior; rather than determine if a behavior exists in animals because it is found in humans, comparative psychologists are beginning to pay attention to the social and ecological context of their subjects and ask how adaptation has shaped a given behavior (e.g., Salwiczek, et al. 2012).

Salwiczek, L. H., L. Prétôt, and L. Demarta, et al. 2012. cleaner wrasse outperform capuchin monkeys, chimpanzees and orang­utans in a complex foraging task derived from cleaner­client reef fish cooperation. PloS One 7.11: e49068. This study compared three primate species with a fish species on their ability to choose between two actions with identical immediate rewards, but only one of which included an additional delayed reward. The fish outperformed the primates on the initial task, but not the reversal task, which is evidence that certain cognitive abilities are selected for due to ecological pressures.

Vonk, Jennifer, and Todd K. Shackelford, eds. 2012. The Oxford handbook of comparative evolutionary psychology. New York: Oxford Univ. Press. Whereas much focus has been placed on cognitive continuity between species, (re­)emphasis has been placed on the ecological and evolutionary context of behavior. This edited volume brings an explicitly evolutionary approach to topics traditionally covered in comparative psychology.

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