The Almost Blank Slate Making a Case for Human Nurture

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The Almost Blank Slate Making A Case For Human Nurture

HENRY D. SCHLINGER

IN 2002, THE PSYCHOLOGIST STEVEN PINKER A Case for Human Nurture appeared on the New York Times bestseller list In his review of Pinker’s book, the behavioral with The Blank Slate: The Modern Denial of biologist Patrick Bateson wrote that it may lead Human Nature,1 a book that attempts to catapult to “yet another round of the tedious and increas- the nature-nurture issue back into public debate, ingly irrelevant nature/nurture debate.” 2 while squarely coming down on the side of Although I resist being drawn into more tedious human nature. I shall argue, however, that there debate on the nature-nurture issue, Pinker’s is overwhelming evidence that learning exerts prominence as a public intellectual demands a the most significant influence on human behav- rejoinder and compels me to make the following ior—a fact that is rarely acknowledged, publi- assertions: cized or even understood. If anything, there is a • Humans come into the world much closer modern denial of human nurture, not human to the blank slate end of the continuum than any nature. other species.

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• Most of what humans know or know how The crux of the debate is not whether genes to do is not present in any form at birth. influence learning or behavior—no behavioral • Many, if not most, of the important similari- scientist would claim they don’t—but rather how ties and differences in behavior between individ- they influence learning and behavior.5 The flip uals can parsimoniously be explained due to side of the question, and the one of interest to learning. me as a behavioral psychologist, is how the These are so obviously true it seems odd to experiences we call learning influence behavior. have to repeat them, but the scientific evidence This question is much easier to answer because for the influence of learning on human behavior the experiences that produce learning are easily is overwhelming. accessible to experimental scrutiny and there All other species rely more upon reflexes or already exist decades of sound experimental fixed-action patterns that, although not insensitive work from which to draw. But first we must clar- to learning experiences, are relatively stable. ify the relationship between learning and evolu- Examples include aggressive displays, courtship tion by natural selection as causes of behavior. and mating, migration, imprinting, and care of young. Human behavior, on the other hand, is Ultimate Causation of Behavior noteworthy for its variability. As the evolutionary The nature-nurture debate is typically portrayed biologist Douglas Futuyma so aptly put it: “On as a simplistic paradigm where, in the nature cor- balance, the evidence for the modifiability of ner, proponents claim that genes exert the over- human behavior is so great that genetic con- riding influence on human behavior, such as lan- straints on our behavior hardly seem to exist. guage, intelligence, and social and sexual rela- The dominant factor in recent human evolution tions. In the nurture corner, proponents argue has been the evolution of behavioral flexibility, that learning exerts the overwhelming influence. the ability to learn and transmit culture.” 3 Put in these terms the nurture proponents win The renowned evolutionary biologist, Ernst hands down. In other words, even though our Mayr, has also acknowledged the flexibility of ability to learn is made possible by a nervous human behavior with his distinction between system shaped by a particular evolutionary histo- open and closed programs. According to Mayr, ry, the experiences scientists call learning “closed programs” include reflexes and account for most of the similarities and differ- fixed-action patterns controlled by areas of the ences between individuals. In this regard, as brain that are rigidly programmed by genes. behavioral psychologist Galen Alessi suggests, Other areas of the brain (e.g., the language learning may be viewed, along with evolution, as areas) are suitable for “open programs” because a set of ultimate causations of behavior.6 the information is not rigidly programmed the Since at least the early 1960s, Ernst Mayr has way that reflexes are. These areas are primed by argued that every process in living organisms is certain learning experiences early in life while the result of two separate causations called proxi- even more general areas of the brain (e.g., the mate (i.e., functional) and ultimate (i.e., evolu- association cortices) remain malleable to learning tionary). Ultimate causation explains why an experiences throughout life.4 organism is the way it is, as a product of evolu- No one would deny that genes, selected tion. According to Mayr, because ultimate causa- throughout human evolutionary history, code for tion relates to the origin of adaptation or diversity, a nervous system that makes possible our it answers “Why?” questions, such as “Why are extraordinary ability to learn, or that some genes desert animals usually colored like the substrate?” may be specialized for such learning. But let us Such questions “deal with the historical and evo- not forget that all genetic expression, from rela- lutionary factors that account for all aspects of tively simple Mendelian traits such as eye color, living organisms that exist now or have existed to complex behavioral tendencies such as verbal in the past.” Mayr reminds us that it was Darwin behavior, is dependent on environmental input. who was responsible for making “Why?” ques- Such input can be located on a continuum from tions scientifically legitimate and for bringing “all the very simple stimuli that elicit reflexes to the of natural history into science.”7 complex associative processes that produce If we want to know why an organism learning. exhibits a particular behavior, we are asking

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about the behavior’s natural history and its ulti- point, however, locating areas of the brain relat- mate causation. Therefore, it makes sense to ed to certain behaviors in no way implicates adopt Alessi’s modification of Mayr’s strictly evo- inheritance as an ultimate cause. For example, a lutionary (or phylogenetic) account of ultimate recent study compared brain scans during recog- causation to include the life history (or ontogeny) nition tests in adults, who as children were of the organism. Thus, in this neo-Mayrian view, judged as shy or inhibited, with adults who were the ultimate causes of behavior, especially in not judged as shy.13 The results showed more humans, occur in both the evolutionary history activity in a certain area (the amygdala) of the of the species and in the learning history of the brains of the once-shy adults. The media report- individual. Explanations involving both types of ed that the study lent support for the inheritance ultimate causations necessarily involve specula- of shyness. However, nothing in these, or any tive accounts of the natural history of the behav- other results purportedly showing brain-behavior ioral phenotype—interpretations based on basic relationships, suggests inheritance as the ultimate principles of evolution and learning and carried cause. Simply identifying structures in the brain out by evolutionary biologists and behavioral that seem to relate to behavior does not in and psychologists respectively. of itself implicate either evolution or learning as the ultimate cause. Evolution, Learning and the Nervous System In fact, a sizeable body of research shows Naturists try to buttress their position by mar- that learning changes the physical and chemical shalling evidence from neurobiology. They do structure of the brain. Readers may already be this in at least two ways. First, evolutionary psy- familiar with experiments by Mark Rosenzweig, chologists assert that there are specifically William T. Greenough, and their colleagues evolved modules in the brain that underlie partic- which show that placing rats in either impover- ular human abilities.8 Other scientists seriously ished or enriched environments produced question such claims, however. For example, changes not only in their behavior but also in the neuroevolutionary psychobiologists Jaak and structure of neurons and synapses in their brains Jules Panksepp bluntly state, “By simply accept- (e.g., dendritic branching, synaptic and neuronal ing the remarkable degree of neocortical plastici- density, and synapses per neuron).14,15,16 Other ty within the human brain, especially during research on non-human animals shows that spe- development, genetically dictated, sociobiological cific learning experiences produce measurable ‘modules’ begin to resemble products of dubious changes in the nervous system. For example, the human ambition rather than of sound scientific Nobel prize-winning neuroscientist Eric Kandel reasoning.”9 Psychologist William Uttal calls this and his associates have shown changes in the modular approach “the new phrenology.”10 In structure and function of individual neurons as a fact, serious scholars argue that instead of con- function of classical (Pavlovian) conditioning.17 taining specifically evolved and specialized mod- And research by Joseph LeDoux and his col- ules (for emotion, language, etc.) as evolutionary leagues has shown that classically conditioned psychologists suggest, the human brain is more fear in rodents changes the amygdala, which accurately described as consisting of subcortical controls fear reactions by way of output projec- systems shared with other mammals that interact tions to the behavioral, autonomic, and with a more recently evolved human neocortex endocrine response control systems located in that is specialized for learning.11 the brainstem.18 Second, naturists point to studies using Of more interest, however, are data showing brain-imaging technologies to support their that learning experiences produce changes in the claims of the inheritability of behavior. It is fash- human brain. One recent study showed that ionable nowadays for psychologists and neuro- behavioral methods used to ameliorate dyslexia scientists to use functional Magnetic Resonance in children both improved reading performance Imaging (fMRI) scans to view the brain while and increased activity in corresponding brain subjects engage in various activities. Despite a areas as observed using fMRI.19 In another study, flurry of such studies in recent years, some schol- PET scans found metabolic changes in associated ars note serious methodological and interpretive brain areas in patients with major depressive problems that plague this research.12 More to the disorders who were treated with interpersonal

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psychotherapy as well as with medication.”20 Yet to require an ad hoc selected brain structure. All the another study showed that successful behavior achievements of the human intellect were reached modification of obsessive compulsive disorder with brains not specifically selected for these tasks produced changes in the function of a part of the by the Darwinian process.24 brain called the caudate nucleus.21 Pinker regards these facts as obvious and From Genes To Behavior unconvincing. But they do lend support for a The pathway from genes to behavior is anything view of the human brain in which the neuro- but straightforward, thus rendering many genetic physiological underpinnings of behavior are (and neurological) explanations of behavior over- established by learning experiences rather than ly simplistic. Genes do not code directly for any being specialized evolved modules. Pinker is cor- trait, especially behavior. Genes code for pro- rect about one thing, however: “Neural plasticity teins, which constitute the entire body including is just another name for learning and develop- the nervous system. One of the functions of the ment, described at a different level of analysis.” 22 nervous system is behavior—the actions of mus- This echoes B.F. Skinner’s contention that we cles and glands in response to environmental may study laws of learning without knowledge stimulation. Perhaps more than any other pheno- or consideration of the underlying neural struc- typic trait, behavior does not occur in a vacuum; tures and processes. the expression of behavior always depends on Although I am reluctant to use the phrase substantial environmental input. “blank slate” for fear of being caricatured, I will So, while the ultimate causes of an individ- venture to say that the human neonate’s cortex is ual’s behavior occur in the evolutionary history a relative blank slate. And there is neurological of the species (as coded in the genes) and in that evidence to support this contention. The well- individual’s past experiences, both processes pro- known pediatric neurologist, Harry Chugani and duce their effects first on the structure of the his colleagues use Positron Emission brain, the former mostly during prenatal develop- Tomography (PET) scans, which measure glu- ment and the latter mostly after birth. It is impor- cose metabolism that occurs when neurons fire, tant to note here that although evolutionary cau- to compare brain activity in newborns to that in sation of structural or behavioral traits is coded in older children and adults. In general, they find the genes, the causation is not in the genes. the most activity in the neonate’s brain occurs in Likewise, although the causation of behavioral the primary sensory and motor cortexes, thala- traits due to learning is coded somehow in the mus, and brainstem, areas associated with the nervous system, the causation is not in the nerv- primitive reflexes seen in infants. Activity in the ous system as some authors strongly imply.25 frontal association cortex and other cortical areas Because of the complex interactions between associated with “higher cortical and cognitive learning and inheritance, their relative contribu- function” is relatively nonexistent. As the infant is tions to behavior cannot be teased apart and cer- exposed to more and more learning experiences, tainly not by the heritability studies of behavior as a result of interacting with the social and non- geneticists. Such studies, flawed as they are social environments, areas of the cortex that methodologically, can at best only estimate the mediate these behaviors show more activity.23 correlation between questionable phenotypic dif- In addition to neurological data, anthropolog- ferences in a population, such as differences in ical and anatomical evidence corroborates a gen- IQ scores, and genetic differences.26 eral-purpose model of the human cortex. Ernst Mayr explained it this way: What Modern Denial? Is there a modern denial of human nature? I There is much to indicate that physically the human don’t think so. In fact, quite the opposite. Hardly brain reached its present capacity nearly 100,000 a day goes without hearing about research on years ago, at a time when our ancestors were cul- the role of inheritance in depression, homosexu- turally still at a very primitive level. The brain of ality, intelligence, language, promiscuity, dyslexia, 100,000 years ago is the same brain that is now anorexia, and so on. And evolutionary psycholo- able to design computers. The highly specialized gy is such a hot field that some individuals have mental activities we see in humans today seem not simply become evolutionary psychologists by

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declaration, without any special training in biolo- the Russian physiologist Ivan Pavlov and, con- gy, evolutionary theory, genetics, or without con- trary to its popular reputation of dealing only ducting any scientific research in these areas. with slobbering dogs, it has now been shown to Moreover, many of the claims made by evolu- influence a range of phenomena in humans, tionary psychologists are elaborate just-so stories, including anxiety and phobias, physical depend- based on less than adequate scientific evidence ence produced by drugs such as heroin and or logic.27 Countless introductory psychology alcohol, taste-aversions, psychosomatic disorders, textbooks now include sections on evolutionary sexual arousal, and immunosuppression caused psychology, not because a strong case for it has by treatments for cancer. been made, but because it is currently in vogue Operant learning has been shown to account to explain behavior due to genes selected during for a much wider range of behaviors, including the Pleistocene era when we were hunters and most if not all actions involving skeletal muscle gatherers. activity. Operant learning has been observed in I would contend that, if anything, there is a species ranging from simple to complex, and has modern denial of the role of learning in human even been observed in individual nerve cells.28 behavior. There are several possible reasons, Because of its ubiquity and its relevance to including poor public relations by learning theo- behaviors related to language, intelligence, and rists and simple ignorance by the media, the consciousness, it is surprising that learning is public, and even psychologists about the volumi- rarely mentioned by psychological scholars. nous research over the past century on the specific ways in which experiences change behavior. Learning as a Parsimonious Explanation of Behavior Perhaps most important, the experiences we In many instances where evolutionary explana- refer to as learning are extremely complex and tions are offered for human behavior, learning occur with such speed and fluidity and at such a explanations are more parsimonious, which constant rate that their observation is rendered means they explain the same facts with fewer difficult even under controlled laboratory condi- assumptions. Consider phobias. Sociobiologist E. tions. Another possible factor in the denial of O. Wilson claims that humans have a genetic learning is that if we acknowledge that learning aversion to snakes as evidenced by his con- accounts for the most important similarities and tention that humans are much more likely to differences in human behavior, then it becomes develop “fear and even full-blown phobias” to harder for us to shirk our responsibility in solving snakes than to guns, knives, and automobiles. problems caused by human behavior. For Wilson, this aversion to snakes is due to the “constant exposure through evolutionary time to What Is Learning? the malign influence of snakes,” with “the repeat- Learning is typically defined in terms of specific ed experience encoded by natural selection as a changes in behavior due to certain kinds of hereditary aversion and fascination.”29 experiences. Over the past century, scientists First we must realize that not everyone who have discovered two, often overlapping kinds of is bitten by a snake will learn to fear snakes, so experiences, called classical and operant learn- we must have a science that can account for ing, which produce such behavioral changes. In such individual differences. Nevertheless, if we classical learning an otherwise neutral stimulus, assume that, in general, humans are more likely such as the sight of a dog, can come to elicit a to develop fears and phobias to snakes than to response, such as fear, if the sight of a dog cars or knives, the question we must ask is what occurs reliably with a stimulus that already elicits most parsimoniously explains it. The sociobiolog- fear, such as being bitten by that dog. In operant ical explanation is appealing and makes evolu- learning, behaviors are either strengthened (rein- tionary sense, but a number of learning explana- forced) or weakened (punished) by their conse- tions offer a simpler account. For example, it is quences. For example, if a parent gives a child well documented in the Pavlovian conditioning candy (reinforcing consequence) every time a literature that the tendency to acquire specific child screams, then the child will continue to conditioned reflexes (in this case, fears) is deter- scream or scream more. mined by the relative amount of experience one Classical conditioning was first quantified by has with the stimuli that produce the reflexes:

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The more numerous the experiences with an of which, by the way, are dangerous). object without adverse consequences, the longer it takes a fear to develop when there is an The Denial of Learning in Human Behavior adverse consequence. For example, a typical per- To find evidence of a modem denial of human son in our culture has countless experiences with learning, one need took no further than the field cars and knives without any adverse conse- of psychology. Most introductory psychology quences. If we are in an automobile accident or textbooks devote an entire chapter to the princi- are cut by a knife, it is only one unpleasant ples of classical, operant and social learning. experience in a sea of experiences with those Learning is said to account for much of human objects that have not produced adverse conse- behavior. But then, oddly, those principles are quences, so we are less likely to develop a fear. rarely if ever mentioned in succeeding chapters Learning theorists would say that the myriad that deal with learned behaviors involved in non-aversive experiences with knives and cars remembering, perceiving, talking, thinking, or have produced a latent inhibition with respect to emotional responses. Learning is even given developing conditioned emotional responses short shrift when dealing with such obvious (i.e., fears) to them. That means that it would examples as social and maladaptive behaviors, take relatively many more unpleasant or painful despite the fact that it has been demonstrated to experiences before fear toward those objects be a critical determinant of many of these behav- would develop. iors. For example, nowadays it is customary to Most of us, however, have very few, if any, explain problem behaviors such as anxiety, direct experiences with snakes. If one of those depression, ADHD, and learning disabilities as rare experiences produces an adverse outcome having a strong inherited component. Learning, (e.g., the snake bites us) it may be more likely to however, provides a much simpler and more condition a fear quickly because there is no easily testable explanation; but the learning built-up reservoir of non-aversive experiences to account gets little press. Moreover, effective ther- counter it. So, the speed of learning may be due apies for treating these behavioral problems to those experiences rather than to a specific come not from evolutionary psychology, but evolutionary predisposition. from learning theory. Fear of snakes can also be acquired by Because of the almost infinite flexibility of the observing and modeling others’ extreme reac- human cortex, learning determines most every- tions to them (either in real life or in movies) thing we do. Among the behaviors we learn are and, relatedly, by being told about someone’s talking, reading, writing, doing math, thinking bad experience with a snake. Interestingly, logically, interacting socially, and playing sports Pavlovian learning is implicated in these types of and musical instruments. Even behaviors that on learning as well.30 Finally, as Stuart Vyse of the surface seem to represent closed programs, Connecticut College reminds us: “Because they such as standing, walking, reaching and grasp- are live animals, snakes are less predictable and ing, and perceptual abilities have a significant controllable than objects such as cars or knives. learned component. Many theorists who deny Being physically close to a knife is not risky, the importance of learning in human behavior whereas being physically close to a snake can often pay lip service to it, but for them it is never be.”31 Perhaps what we’ve inherited is a predis- more than some unspecified, passive process; a position to learn fears quickly from such unpre- mere annoyance along the road to understanding dictable and uncontrollable events. But we must what they perceive to be the essence of human learn the fear of snakes nonetheless. In the case behavior—genes. of phobias, learning explanations are preferable to sociobiological explanations because they The Denial of Learning Language require fewer assumptions and because the prin- Often learning is flatly denied for behaviors that ciples to which they refer—latent inhibition and clearly have a strong learned component. In his modeling—have been demonstrated in countless book, The Language Instinct, for example, Pinker experiments. The evolutionary explanation writes, in his usual self-assured manner: “First, let requires many assumptions about the history of us do away with the folklore that parents teach hominids and their relationship to snakes (not all their children language.” Pinker compares

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language to sitting, standing, and walking which, “Thought provoking and according to him, parents don’t teach but which well-argued…” children do anyway. Pinker also denies the role —Library Journal of imitation in language learning when he writes, “The very concept of imitation is suspect to begin with (if children are such general imitators BRAIN & why don’t they imitate their parents’ habit of sitting quietly in airplanes?)” and that, “normal chil- BELIEF dren do not learn language by imitating their An Exploration parents.”32 of the Human Soul Statements such as these reveal no apprecia- tion for the subtle power of learning, and a lack $14.95 • ISBN 0-9747645-0-7 of knowledge of the sizeable body of experimental research on it. When linguists and psy- Available online chologists repeat the tired rhetoric that parents or through don’t teach their children language, what they your local bookstore mean is that parents don’t intentionally teach their children how to talk, as if anyone ever sug- “I know of no other single volume that covers such a wide range of topics gested this. That does not mean, however, that and still retains a depth of analysis…this book is an important addition to children don’t learn language from parents. Just the pantheon of popular science books that should be read not only by as learning theorists in the 1960s reanalyzed general readers, but by professional scientists, philosophers, and scholars of tapes of the so-called “non-directive” therapy all stripes. And it’s a good read to boot!” —Michael Shermer sessions by the humanist psychotherapist Carl Rogers and discovered that he was actually rein- www.theaegispress.com forcing his clients’ positive self-statements (forcing Rogers to change the name of his approach to “client-centered”),33 psychologist Ernst Moerk exhaustively reanalyzed psychologist Roger Evolution vs. Creationism Brown’s data on early language interactions An Introduction between mothers and children and, in so doing, identified detailed instances of mothers prompt- Eugenie C. Scott ing and reinforcing vocal imitations and shaping by successive approximations, among other Provides a badly needed, comprehensive, and balanced introduction behavioral processes.34 Such processes are subtle to the many facets of the current debate over the teaching of evolu- and difficult to identify if one’s view of reinforce- tion. Includes: the scientific evidence for evolution; the legal and ment is a naive, simplistic one in which only educational basis for its teaching; various religious points of view, praise for speaking appropriately counts. The and a concise history of the evolution- principle of reinforcement derives from the more creationism controversy. A section of general Law of Effect, which states that behavior primary source documents from all is determined by its consequences. Specifically, sides of the issue is included. reinforcement is any consequence produced by a Eugenie C. Scott is the executive behavior that causes that behavior to occur again director of the National Center for (or to be strengthened) under similar circum- Science Education, a non-profit stances. Thus, reinforcement is defined by how it organization that defends the teaching functions and, in a manner analogous to natural of evolution in the public schools. selection, reinforcement operates on (selects from) behavioral variation. $49.95 • ISBN 0-313-32122-1 Greenwood Press, 2004 The Reinforcement of Babbling A good example of the subtle role of reinforce- Buy it on-line: www.ncseweb.org/evc ment in language acquisition is babbling. Babbling in infants begins at around 4-6 months

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of age when the larynx descends into the throat. and expressions. Other people don’t intentionally Instead of being able to breathe and drink simul- reinforce us for talking like them except in the taneously as babies can do before that time, they usual ways by listening and responding. Hearing can now make all of the phonetic sounds found ourselves sound like our friends or using trendy in all human languages. The question is how this words automatically reinforces the use of these amorphous sea of phonemes is transformed into words or expressions in the sense that we con- the intelligible sounds of the parents’ language tinue to use them. The process occurs without usually by the second year of life. Someone awareness, but it occurs nonetheless. In addition naive about learning theory might answer by to this interpretation being parsimonious, it has saying that parents reinforce the sounds they like experimental support.35 and ignore the sounds they don’t like. While most parents do respond more excitedly when Learning “Real” Words their infants make sounds, especially recogniza- Detractors may claim that babbling is not real ble ones, this probably only contributes to the language, so we must provide other examples of continued strength of (i.e., reinforces) the infant’s how language is learned. Once the phonemic efforts, not to the shaping of specific phonemes. sounds and sound combinations of a child’s Only a misunderstanding of reinforcement native language have been shaped by automatic would lead one to claim that it plays no role in reinforcement, parents are ready to hear “real” the acquisition and maintenance of infant (or words, so when they hear “mama” or “dada” even adult) speech. Although parents do inten- they respond excitedly, often repeating the word tionally reinforce verbal behavior in their chil- (both reactions functioning as reinforcement), dren, the form of reinforcement that is responsi- and continue to do so as new words emerge. ble for shaping infant babbling into the recogniz- And, yes, they also use imitation to teach new able phonemes of their native language is a words, as in, “Say spoon,” or “Can you say more subtle form called automatic spoon?” and then responding, “Right, spoon.” reinforcement. When children use words to request things (e.g., Here’s how it works. Beginning before birth, food, comfort, relief from pain), parents provide infants hear countless hours of human chatter. those things. The parents’ responses are not nec- When they begin to babble, some of the sounds essary for children to learn how to say words— they make (i.e., those of their native language) they learn that through imitation—but they are “sound good” and familiar in the sense that they necessary for children to learn to use words. match the sounds the infants have heard since I’ve always been amazed that Chomsky and before birth. The rest of the sounds they hear Pinker don’t seem to understand that, more than themselves utter are not familiar. Hearing them- any other behavior, verbal behavior is social selves match familiar sounds reinforces those behavior, and in the absence of an environment sounds “automatically,” in that no other person where words and sentences do something for reinforces them, and so the infants keep making the speaker, they won’t occur. Following from them. This is the main reason that deaf infants Darwin, we must look for the function of behav- stop babbling. Automatic reinforcement also ior. For example, an infant raised all alone on a explains why the cadence and inflection of infant desert island with a tape player constantly play- babbling sounds as if the infant is actually talking human speech may eventually learn to say ing, something that drives parents crazy trying to some words, but the words will never be used in understand what their babbling infants are saying a functional way because they won’t do anything (of course, they’re not saying anything). In this for the child. The words won’t get the infant any- case, not only are the individual phonemes thing in the absence of other people (listeners) uttered by the infant automatically reinforced by who know how to respond to the infant’s their similarity to what the infant has heard, but requests. The infant will be little more than a so too is their cadence and inflection. parrot. This explains a popular example that The same phenomenon occurs when we Chomskian linguists use to counter the sugges- take on colloquial expressions or accents of tion that language is learned and to support the roommates or friends whom we like or admire, suggestion of a Language Acquisition Device or when we find ourselves using trendy words (LAD), namely that the children of immigrants

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who spend their time in the streets playing with they offer a compelling picture of the enormous other children learn the language of their adop- impact learning has on language acquisition. tive country faster than their parents who take Finally, Pinker’s claim that children do not classes. As anyone who ever took a foreign lan- learn by imitating is simply wrong, as Claire guage class in school knows, learning a language Poulson and her colleagues, among numerous in a classroom doesn’t teach many conversational others, have shown.37 True, children do not imi- skills, whereas being immersed in a language tate everything their parents say or do. But when environment will teach conversational skills imitating produces reinforcing consequences, because the words you learn actually produce children imitate—and so do adults. Anyone who immediate and naturally reinforcing effects. has been around a young child knows that they Countless experiments have shown that vari- imitate much of what they hear and see, and ous aspects of language, including grammar, can children and adults use imitation and modeling be acquired through operant and social learning. as the main way to learn words and simple sen- However, a longitudinal study by Betty Hart and tences in the first place. Todd Risley demonstrates convincingly that parents’ language and interaction styles determine Conclusion their children’s language and interaction styles.36 We must not overlook the importance of evolu- This study, and the dozens showing the operant tion and inheritance, especially when explaining learning of language, should put to rest once and the distinguishing differences between humans for all the critics’ claims that children don’t learn and other animals. At the same time, we must language from their parents. not deny the importance of human learning. If In Hart and Risley’s study, language interac- we overlook learning as the primary determinant tions between 42 American children, from birth of human behavior in our search for elusive to 2.5 years of age, and their families were genes and vague mental constructs, we will be at observed in the home for one hour a month. Not a big disadvantage in solving serious problems. only was the children’s amount of talking shown Knowledge of learning principles in developing to be directly related to the parents’ amount of programs of behavior therapy and applied talking, but 86-98% of the actual words in the behavior analysis has already greatly improved child’s vocabulary were also in the parents’ the lives of children with autism and other devel- vocabulary. There were strong correlations opmental disabilities and behavioral problems, as between what the parents actually did during well as otherwise normal children and adults in a interactions with their language-learning children variety of settings from the home to the school to and the children’s language development. For the workplace. example, the children’s rate of vocabulary growth In his keynote address to the 98th Annual was a direct function of how many different Convention of the American Psychological nouns and modifiers they heard and how much Association in 1990 (a week before his death), the parents reinforced the children’s utterances the famous American psychologist, B. F. Skinner either with approval or by repeating what the noted, “After almost a century and a half, evolu- children said. These relationships held up at age tion is still not widely understood. It is vigorously 3, as they also did with the children’s perform- opposed by defenders of a creator…. The role of ances on standardized achievement and intelli- variation and selection [learning] in the behavior gence tests (i.e., IQ scores) when they were nine of the individual suffers from the same opposi- years old. In addition, the data also revealed tion.”38 One can only hope that with time and slower vocabulary growth rates when parents ini- better scientific training of psychologists, learning tiated verbal interactions (v. reinforcing the child will be universally recognized as the most impor- for initiating) or issued imperatives (v. questions tant element of human behavior. t or choices) or outright prohibitions (punishment) for speaking. ————————————————————————— The data from the Hart and Risley study are I am grateful to Julie Riggott and Stuart Vyse for their helpful real data from real parents teaching their children comments on this essay. Correspondence may be addressed to the author, Department of Psychology, California State a real language, not the idealized sentences or University, Northridge, 18111 Nordhoff Street, Northridge, CA, rationalist musings of Chomskian linguists, and 91330-8255. Email: [email protected].

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References on Rat Visual Cortex Synapses. I. Analysis of the Just-So Stories of 1. Pinker, Steven. 2002. The Blank Synaptic and Neuronal Density and Evolutionary Psychology.” Skeptic, Slate: The Modern Denial of Human Synapses Per Neuron.” Brain Res. 10/4, 68-76. Nature. New York: Viking. 329. 195-203. 28. Stein, L., and J. D. Belluzzi. 1988. 2. Bateson, Patrick. September, 2002. 17. Kandel, E. R. 2000. “Cellular “Operant Conditioning of Individual “The Corpse of a Wearisome Mech-anisms of Learning and the Neurons.” In M. Commons, R. M. Debate.” Science, 297 (27), 2212- Biological Basis of Individuality.” In Church, J. R. Stellar, and A. Wagner 2213. E. R. Kandel, J.H. Schwartz, and T. (Eds.), Quantitative Analyses of 3. Futuyma, Douglas J. 1979. M. Jessell (Eds.) Principles of Neural Behavior: Biological Determinants of Evolutionary Biology, Sunderland, Science (4th ed.), New York: Reinforcement. Hillsdale, NJ: MA.: Sinauer, 491. McGraw-Hill. Erlbaum, 249-264. 4. Mayr, Ernst. 1997. This is Biology: 18. LeDoux, J. L. 2000. “Emotional 29. Wilson, E. 0. 1993. “Biophilia and The Science of the Living World. Circuits in the Brain.” Annu. Rev. the Conservation Ethic.” In S. R. Cambridge, MA: Harvard University Neurosci., 23, 155-184. Kellert and E. 0. Wilson (Eds.) The Press 19. Temple, E., G. K. Deutsch, A. J. Biophilia Hypothesis. Washington, 5. Weiner, J. 1999. Time, Love, Poldrack, S. L. Milleri, P. Tallal, M. D.C.: Island Press, 34. Memory: A Great Biologist and His M. Merzenichi, and J. D. E. Gabrieli. 30. Schlinger, Henry. D. 1996. “What’s Quest for the Origins of Behavior. 2003. “Neural Deficits in Children Wrong With Evolutionary Explanations New York: Vintage Books. With Dyslexia Ameliorated by of Human Behavior.” Behavior and 6. Alessi, G. 1992. “Models of Behavioral Remediation: Evidence Social Issues, 6, 35-54. Proximate and Ultimate Causation in from Functional MRI.” Proceedings 31. Personal Communication. Psychology.” American Psychologist, of the National Academy of 32. Pinker, Steven. 1994. The 47, 1359-1370. Sciences, 100, 2860-2865. Language Instinct: How the Mind 7. Mayr, 1997, 115. 20. Brody, A. L., S. Saxena, P. Creates Language. New York, 8. Cosmides, L. and J. Tooby. 2000. Stoessel, L. A. Gillies, L. A. Harper-Collins, 38. “Evolutionary Psychology and the Fairbanks, S. Alborzian, M. E. 33. Truax, C. B. 1966. “Reinforcement Emotions.” In: Lewis, M. and J. Phelps, S. Huang, H. Wu, M. L. Ho, and Nonreinforcement in Rogerian Haviland (eds). The Handbook of M. K. Ho, S. C. Au, K. Maidment, Psychotherapy.” Journal of Abnormal Emotions, 2nd edition. New York: and L. R. Baxter. 2001. “Regional Psychology, 71, 1-9. Guilford, 91–116. Brain Metabolic Changes in Patients 34. Moerk, E. L. 1992. First Language: 9. Panksepp, J., and J. B. Panksepp. with Major Depression Treated with Taught and Learned. Baltimore: Paul 2000. “The Seven Sins of Either Paroxetine or Interpersonal H. Brookes. Evolutionary Psychology.” Evolution Therapy.” Archives of General 35. Sundberg, M.L., J. Michael, J. W. and Cognition, 6, 108-131: 108. Psychiatry, 58, 631-640. Partington, and C. A. Sundberg. 10. Uttal, William R. 2001. The New 21. Schwartz, J. M., P. W. Stoessel, L. 1996. “The Role of Automatic Phrenology: The Limits of Localizing R. Batxer, K. M. Martin, and M. E. Reinforcement in Early Language Cognitive Functions in the Brain. Phelps. 1996. “The Systematic Acquisition.” The Analysis of Verbal Cambridge MA: MIT Press. Changes in Cerebral Glucose Behavior, 13. 21-37; Smith, R., J. 11. Lieberman, Philip. 2003. Human Metabolic Rate After Successful Michael, and M. Sundberg. 1996. Language and our Reptilian Brain: Behavior Modification Treatment of “Automatic Reinforcement and The Subcortical Bases of Speech, Obsessive-Compulsive Disorder.” Automatic Punishment in Infant Syntax and Thought. Cambridge, Archives of General Psychiatry, 53: Vocal Behavior.” The Analysis of MA: Harvard University Press. See 109-113. Verbal Behavior, 13, 39-48. also Panksepp and Panksepp. 22. Pinker, 2002, 86. 36. Hart, B., and T.R. Risley. 1999. 2000, 108-131. 23. Chugani, H. T., M. E. Phelps, and J. The Social World of Children: 12. Faux, Steven F. 2002. “Cognitive C. Mazziotta. 1987.“Positron Learning to Talk. Baltimore: Paul Neuroscience From a Behavioral Emission Tomography Study of Brookes. Hart, B. and T. R. Risley. Perspective: A Critique of Chasing Human Brain Functional 1995. Meaningful Differences in the Ghosts with Geiger Counters.” The Development.” Annals of Neurology, Everyday Experiences of Young Behavior Analyst, 25, 161-173. 22, 487-497. American Children. Baltimore: Paul 13. Schwartz, C. E., C. I. Wright, L. M. 24. Mayr, 1997, 74-75. Brookes. Shin, J. Kagan, and S. L. Rauch. 25. Quartz, S. R., and T. J. Sejnowski. 37. Kymissis, E., and C. L. Poulson. 2003. “Inhibited and Uninhibited 2002. Liars, Lovers, and Heroes: 1990. “The History of Imitation in Infants ‘Grown Up’: Adult Amygdalar What the New Brain Science Learning Theory: The Language Response to Novelty.” Science, Reveals About How We Become Acquisition Process.” Journal of the 300, 1952-1953. Who We Are. New York: William Experimental Analysis of Behavior, 14. Rosenzweig, M. R. 1984. “Exper- Morrow. 54, 113-127. Poulson, C. L., E. ience, Memory, and the Brain.” 26. Joseph, J. 2003. The Gene Kymissis, K. F. Reeve, M. American Psychologist, 39, 365-376. Illusion: Genetic Research in Andreatos, and L. Reeve, 1991. 15. Greenough W. T., F. R. Volkmar. Psychiatry and Psychology Under the “Generalized Vocal Imitation in 1973. “Pattern of Dendritic Microscope. Herefordshire, England: Infants.” Journal of Experimental Branching in Occipital Cortex of Rats PCCS Books. Schlinger, H. D. 2003. Child Psychology, 51, 267-279. Reared in Complex Environments.” “The Myth of Intelligence. “The 38. Skinner, B.F. 1990.“Can Psych- Exp. Neurol. 40, 491-504. Psychological Record, 53, 15-32. ology be a Science of Mind?” 167. Turner A. M., W. T. Greenough. 27. Schlinger, Henry. D. 1996. “How American Psychologist, 45, 1985. “Differential Rearing Effects the Human Got its Spots: A Critical 1206-1210.