MEDIA REVIEW

Let’s Think it Over Again: A Neobehaviorist View ofCognition in Animals

Review of Intelligence of Apes and Other Rational Beings by Duane M. Rumbaughand David A. Washburn. New Haven, Yale University Press, 2003, xvii þ 326 pp,30 figures, 1 table, $35.

‘‘ywhy animals do not speak as we do is not that they lack the organs but thatthey have no thoughts’’ (Descartes, 1646, cited by Edward Wasserman in TheCognitive Animal: Empirical and Theoretical Perspectives on Animal Cognition.‘‘General signs’’).‘‘I am thinking therefore I exist.’’ (Descartes, Discourse on Method, 1637, IV).

THE BOOK IN A NUTSHELL

Radical behaviorists, such as John Watson and B.F. Skinner, have proposedthat the results of muscular activity alone are the proper data for understandingbehavior. In this view, all behavior is built upon unlearned processes that areshaped into their adult form through respondent (classical) and operant(instrumental) conditioning. There is no need to enter the organism’s interioranatomy or physiology, or to probe any internal processes, such as thought(assuming that there is any thinking going on in the first place). This view, whichis generally rejected in contemporary comparative, cognitive, and developmentalpsychology, is elegantly rejected throughout this book.

Neobehaviorists, such as Rumbaugh and Washburn (henceforth calledR&W), differ radically from this view. They define behavior in terms of patternedneural events as well as coordinated muscle activity. In their perspective, therational behavior of primates and other large-brain mammals is produced by thesum of unlearned species-specific responses, operants, respondents, and emergentnovel behavior patterns. These emergent abilities are produced by the naturalactivities of complex brains in detecting patterns, inventing categories thatorganize perception and experience, and finding relationships among thesecategories. The degree and complexity of emergent behavior is said to be based onrearing experiences in environments that afford opportunities for variability inexperience and response, in the predictability of events over time, and in thedevelopment of cognitive tools ranging from simple learning sets to facility with acommunication system, such as human language. The ability to consider pastexperience, the current situation, and possible future outcomes to solve life’s dailyproblemsFin short, thinkingFis a central process in this viewpoint. In support

DOI 10.1002/ajp.20067Published online in Wiley InterScience (www.interscience.wiley.com).

r 2004 Wiley-Liss, Inc.

American Journal of Primatology 64:133–137 (2004)

of rational behaviorism, the 19 chapters of this book are packed into five sectionsthat will entertain, edify, and sometimes mystify the reader.

But do animals think? If they think, do they exist in their own minds? Whatwould Descartes say about the following anecdote?

AN ANECDOTE FROM MY PAST, OR OUTSMARTED AGAINBY A MONKEY

In 1964 I was 1 year into learning about monkeys in Harlow’s Wisconsinlaboratory. In observing juvenile isolation-reared rhesus monkeys, I was struckby their often clumsy motor behaviors, which included difficulty in picking upsmall objects and often missing the handhold when they jumped to a shelf in theplayroom. Since there were no fine motor skill tests (other than pursuit rotors) formonkeys, I decided to invent one. I spent a month on and off working on a reallycool machine, milling a series of ‘‘thimbles’’ out of aluminum stock. The thimblesvaried in height and width in a psychophysically measurable series. The task wasfor the monkey to pick up a small saccharine pellet, with motor ability to bemeasured as the smallest interior area from which the pellet could be extracted.

My first (and, as it turned out, only) subject was a large 10-year-old rhesusmale isolate. He relished the pellets and succeeded nicely at the task until heworked on a 1-inch-high thimble that was barely wider than his index finger. Hetried to roll it up the side for a while, then screamed and hit the thimble a coupleof times, turned his back to the display, and sat in a corner of the test cage forabout 5 minutes. I was about to quit the trial when he turned around, directlyapproached the display, stuck his index finger into his mouth, making it wet, andstuck the finger into the thimble so that the pellet stuck to the finger. He thenextracted the pellet, ate it, and sat alertly waiting for me to rebait the thimble.I ended the trial and gave up on my ‘‘motor skills’’ test. Neither before nor afterdid I see any laboratory-raised rhesus monkey use its finger in this fashion toobtain a food item. If the theory of rational behaviorism had been available to mynaı̈ve self at that time, I would of course have started on a career studying animalthinking. Alas, I might even have had the good fortune of working with DuaneRumbaugh!

THE BOOK IN SOME DETAIL

R&W define animal intelligence as ‘‘using acquired skills and knowledgeinnovatively, to unique advantages in solving novel problems.’’ To justify thisdefinition and the existence of such skills, we are taken on a historical journeythrough Rumbaugh’s 50 years as a comparative psychologist, with specialemphasis on R&W’s collaborative efforts involving computerized learning inprimates. We start with a five-chapter section on the need for rationalbehaviorism. These chapters include a brief history of the comparative psychologyof animal intelligence; a treatise on adaptation, contrasting biological withpsychological smartness, ethology with psychology, and nature with nurture;examples of creative problem-solving by many mammalian species; a review ofclassical learning theory; and the limitations of operant and respondentconditioning in explaining behavior outside of the strict control and limitedstimuli and responses of laboratory environments. Thus, we are told that the real-world behavior of animals is most often composed of both operant and respondentprocesses plus something moreFthe ‘‘more’’ being creative, novel activity. This

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leads to the main question in the book: What are the sources of creative andinventive behaviors in animals?

The next section consists of three chapters that deal with the antecedents ofthe rational behaviorism theory. The authors relate anecdotes from interactionswith chimpanzees, which provided Rumbaugh with questions about cognitivebehavior in animals, and studies at the San Diego Zoo involving comparisons ofrule-learning abilities in a variety of primate species.

Section 3 consists of three chapters on ape language learning. These chaptersare a must for any student of behavior, at any level, who is not familiar with thiswork. The topics include a brief history of ape learning studies, the fascinatingstory of the computer language keyboard and the chimpanzee Lana’s tutelage onit, the social communication skills of chimps Sherman and Austin developed whilethey learned the referential meaning of arbitrary symbols, and the languagelearning exhibited by the bonobo Kanzi while it grew up in a linguisticenvironment without specific language instruction. Kanzi is said to have learnedcomprehension through observation rather than specific instruction, andapparently developed an ability to speak actual English words in proper contextand in innovative ways.

Investigating rational behaviorism across species is the theme of section 4.Here in three chapters we are presented with the basic propositions and evidenceof the R&W theory. This includes a cogent argument concerning why researchresults are always constrained by the methods (including apparatuses) used toproduce them. Thus, it is crucial to ask questions about behavior so that theanimal subjects can provide the right answers. Most studies of ape language priorto those of Rumbaugh and his colleagues were concerned with production. R&Wproposed that the right question to ask involves comprehension, not production.They proceeded to teach comprehension to chimpanzees as the basis fordeveloping linguistic abilities through rearing with socially shared symbols asreferential vehicles for communicating comments, questions, requests, and novelinventions that the learners dream up. Readers can judge for themselves thesuccess of this material in supporting the R&W argument for emergents as‘‘learning about generalized patterns of events that may never have been directlyreinforced.’’

Section 4 also details the history and use of the Language Research Centercomputerized test systemFa methodology that has revolutionized the field ofprimate learning studies. R&W and colleagues developed a series of clever tasksfor this joystick-display screen computer technology. The results show that rhesusmonkey performance potential includes the same qualitative executive functionskills involving inhibition, perception, motivation, and attention that aredisplayed by human children and apes. The section also includes fascinatingstudies on uncertainty monitoring by David Smith and colleagues. In one answerto Descartes, this work comes as close to proving the existence of animal thinkingas one might get without the use of querying by means of a human language. Achapter concerning tasks in which rhesus monkeys fail is presented to illustratetypes of problems that are solved by monkeys using stimulus-response associativelearning, but are solved by apes and children (and ‘‘their larger brains’’) usingrelational rules. However, I was not convinced that the macaque monkeys, whoprobably do not know that they actually have a problem to solve, would not alsosolve many of these problems relationally if they were also raised in a symbolic(linguistic) environment from infancy. Section 4 concludes with a chapter thatdescribes clever experiments indicating that many mammalian species can makeaccurate choices based on numerocity relationships. But, given that this skill

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appears to exist even in pigeons, it is not clear how numerocity perception fits theR&W theory that relational learning requires a large and complex brain.

Section 5 presents five chapters detailing the specific propositions andassumptions of rational behaviorism theory, and tasks and hypotheses that mightbe used to test the theory. As summarized in the Introduction to this review, thetheory integrates instinctive, respondent, and operant learning, and emergentprocesses in explaining how animal brains perform cause-and-effect reasoning tosolve the problems of everyday life, as well as novel threats to their well-being.

Portions of the theory are derived from older concepts. Stimulus saliency is acentral idea, and is defined as an environmental or internal cue of somethingpotentially significant that merits attention. Some stimuli are inherently salient,often species-specific objects or events that require a response in order for theanimal to survive. Other stimuli acquire their salience because they reliably occurtogether in space and time, and come to be perceived as a pattern that providesinformation about a required or desired resource. A major piece of theoreticalnews concerns reinforcement. Reinforcers are considered simply to be paymentfor work performed, rather than events that in themselves strengthen responses.Reinforcers inform an individual of a valued resource that can be earned. They donot cause the animal to learn. Rather, they cause the animal to act and thus beexposed to regularities in the environment, the effects of these regularities onemotional states, and memories produced by these regularities during priorbehavior. Presumably, at least for some species and brain sizes, these regularitiescan provoke thoughts concerning outcomesFnamely, thinking about the future.So, what do animals learn according to the R&W view? They learn salientrelationships that predict the availability of desired outcomes or internal states(e.g., food, water, pleasure, or relief from pain), and perhaps even gather newinformation as an end in itself.

These latter chapters present details about the characteristics of emergentproperties, about what is learned over and above stimulusFstimulus andstimulusFresponse associations, and about the role of rearing experiences inallowing the maximization of emergent skills in a given species. I was especiallyimpressed with a relatively simple experiment on control that seemed to sum upthe idea of an emergent, the requirement of an environment affording variedopportunities, and how an individual might maximize its potential. A procedurecalled CHOOSE is included in the R&W computer test battery. The monkeysubject can play any computer game it wishes for 30 min at a time. It can domatching to samples, shoot at targets, challenge itself with delay problems, runsome mazes, do some visual searching, or even work on a Stroop-like incongruitytask. Remarkable finding number one, at least for someone who has spent yearsdealing with the touch-and-go performances of some monkeys tested with theclassical Wisconsin general test apparatus, is that rhesus monkeys will choose towork on these problems for 30-min periods rather than having access to 30 min offree food rewards. Finding number two, however, is my final answer to Descartesin this review. The monkeys do better in performance when they can choose thetask than when the same task is chosen by the experimenter. Think about it!

SOME FINAL WORDS

This is an enjoyable and interesting book to read, even if you do not buy thetheory. It is also an informative book about primate learning abilities, even if youdo not buy the theory. It is a really good source for student discussions, especiallyat the level of upper-division undergraduates. However, this is not a perfect book

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for the professional psychological scientist who is already knowledgeable aboutlearning, cognitive, or language research. Although R&W mention certain criticsof animal language and thinking ability (such as Tulving, Terrace, and Povinelli),there is no in-depth discussion or refutation of their criticisms in terms of rationalbehaviorism theory. R&W may believe the refutation is self-evident, or perhapsRumbaugh is too much the gentleman to say more than the simple chiding that hegives to Povinelli. I believe a chapter on these critics might have been moreenlightening for both the critics and the average reader to better understand theimplications of rational behaviorism. In any event, I hope you have as good a timereading this book as I did.

Gene (Jim) SackettDepartment of PsychologyUniversity of WashingtonWashington National Primate Research CenterSeattle, WA 98195E-mail: Jsackett@bart.rprc.washington.edu

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