Writings > Development of the Mind and Brain > Part I > Chapter 1

Chapter 1

Each Child Constructs His or Her World

As may be gleaned from the overview, it is my belief that all we have are the constructs that we have in our heads. I, like most of you, believe that there is a real outside world. But all that we know of that world and of our selves is our own constructs. During the course of development, each of us constructs a world and a self through interaction with a particular outside world — and especially with other persons within that world.

A most remarkable aspect of Jean Piaget’s work was his proposal that psychological development is a constructive process. That is, he proposed that during development, very primitive organizations in the nervous system, through interactions between themselves and interactions with the outside world, transform themselves into more sophisticated organizations — constructs of a world of distinct objects, including constructs of self as an object. The interactions take place via the nervous system. The nervous system both limits and enables intrapsychic constructions of the self and the world that generally work fairly well for one to survive and to reproduce.

Piaget used a language that is unfamiliar to most experts in psychology, psychiatry, neuroscience, or philosophy — let alone those who are not experts in these fields. To understand Piaget’s work, particularly his explanation of how the child constructs objects that make up his world, including his self, it is essential to understand Piaget’s concept of the scheme.

Piaget’s Scheme

The scheme was Piaget’s basic building block. In attempting to understand the development of cognition, he began with primitive schemes — undifferentiated psychological structures — and traced their organizational changes from birth to early adulthood.

Piaget’s scheme is a hypothetical, organized, holistic intrapsychic structure that is analogous to a biological cell or organism. The workings of schemes are couched in biological terms, such as assimilation — the taking in of what is needed to sustain the scheme — just as cells and organisms take in what is needed for their sustenance. Although assimilation ordinarily refers to the process of digestion, not to mind or brain processes, it captures the sense of how the scheme operates as it interacts with other schemes and with the external world. A scheme is like a cell or organism that ingests what it can. Later in this chapter, I will show how Piaget’s language may be translated into the language of neuroscience.

From children’s spontaneous behavior, and from their responses to many homey experiments, Piaget inferred the organizational level of the child’s schemes at particular points in cognitive development. In one experiment, he positioned a child’s bottle so that the nipple was not visible to the child. Early in development, the child does not turn the bottle in order to suck the nipple. Later, the child does so. From the later behavior, Piaget inferred that the child’s scheme of seeing the nonbusiness end of the bottle was assimilated to — was now part of — the scheme of seeing and sucking the business end of the bottle. In another experiment, he dropped his watch chain into his hand and made a fist as his daughter watched. She opened his hand and took the watch chain. He repeated the experiment with a change. He dropped the watch chain into his hand, passed his closed fist under a coverlet, where he dropped the chain, brought his fist out, and presented his fist to his daughter. Each time he did this, his daughter opened his fist, but she did not search under the coverlet for the chain. At this point in development, his daughter’s scheme of the watch chain was not a distinct object scheme. Her scheme of the chain was not distinct from her scheme of having seen the watch chain go into his hand. He did similar experiments with all three of his children, varying all the parameters — the objects that were hidden, the types of screens, and their locations. From such experiments it appears that, at this point in development (8-12 mo.), the child’s scheme of having seen an object is not distinct from the child’s scheme of having seen that object disappearing under a screen — for example, into the hand.

Confirming and challenging Piaget’s findings and his interpretations of his findings fostered an industry in developmental psychology. Many developmental psychologists find his work controversial. Some of these psychologists argue that their particular findings show that the child begins life with knowledge of a world composed of separate, solid objects — not that the child must construct such knowledge. Others propose that very young infants understand simple addition and subtraction. Some investigators dismiss Piaget’s findings in infants, because most of his observations and experiments involved just his own three children. Nonetheless, to date, Piaget’s study of his children remains the unparalleled microgenetic — day by day, achievement by achievement — longitudinal study of very early cognitive development. Many of his findings have been replicated in studies of other infants (Decarie, 1965; Uzgiris & Hunt, 1975). Studies of older children done by Piaget and his colleagues on somewhat larger, less biased samples have not resolved the controversy, partly because Piaget did not use statistics. Clearly, I am not the first — nor will I be the last — to quarrel with some of Piaget’s interpretations and yet be inspired by him. There is reason to believe that he would be satisfied with such a legacy — satisfied that he inspired so many other researchers to do their own work. ²

The Nature of Early Schemes

Piaget proposed that the newborn’s schemes center on the sucking, grasping, light seeking, and hearing reflexes. Light seeking and hearing are not as obvious reflexes as are sucking and grasping. But if we think of the newborn’s looking toward a light as visual activation being connected to the extra-ocular muscles that control movement of the eyes, then light-seeking is very much like the sucking or grasping reflex in which touch elicits a muscular response. Light seeking is evident by about the sixth day when the infant tends to keep his eyes aligned with a light as he passes by it (Piaget, 1963). Similarly, hearing is not as clearly a reflex as are sucking and grasping, since the infant is not able to equalize sound to both ears by moving his head until he is about 2 months old.

In the discussion that follows, primarily, I use the sucking scheme to illustrate Piaget’s conceptualization of the scheme and scheme development. I do so because early sucking is the usual center of cognitive-emotional development. As Rochat (2001, p. 52) put it, "The mouth is a privileged locus of learning." And Bornstein and Bornstein wrote,

Infants as young as one month are influenced in which of two shapes to look at if one of the two matches a shape the babies had just explored orally. Indeed, observing a five-month-old in action, one comes away with the impression that in this stage of infancy both vision and reach are in the employ of oral exploration. An object is not fully appreciated until it has been mouthed (2000, p. 7).

Although the sucking scheme is prototypic, it is not the only scheme that may be pivotal in a particular child’s beginning construction of his or her world. For some children, grasping, looking, or listening may be the initial focus of cognitive organization. White (1969) did a longitudinal study of infants in a foundling home. Once a week, he offered a colorful, cylindrical toy to each infant. The infants did not bring the toy to their mouths as frequently as they watched their hands and the toy. At about 4 months they gazed at the toy more often than they grasped it. Children also showed a tendency to gaze at the favored hand even when the object was in the other hand. Apparently for the majority of these children, their primary cognitive scheme was looking (and the favored hand). Blind children and swaddled children must build their worlds of somewhat different sensorimotor activations than other children do.

To comprehend Piaget’s theory, it is critical to understand two of his basic ideas. ² One, the early scheme is undifferentiated and global — that is, primitive. Two, primitive as the early scheme is, to the infant that undifferentiated scheme is the/an object. It is this early, primitive scheme that, in stages, differentiates into schemes that are distinct for different objects, including a scheme (or schemes) of the self that is distinct from other objects.

The nucleus of the sucking scheme is composed of intrapsychic activation directly related to sucking — sensory stimuli that come from the mouth and any intrapsychic reflection of the control of muscles of the tongue and of the mouth.

The newborn’s sucking scheme, however, includes a great deal more than the nucleus. The sucking scheme assimilates — takes in — any cotemporaneous activity patterns. It also assimilates any pattern of sensorimotor neuronal activity that resembles an activity pattern that was part of the sucking scheme in the past. In this way, the sucking scheme becomes widespread and diverse in an infant, and varies from one infant to another.

The newborn’s sucking scheme includes patterns of sensory activation from touch of the nipple; from swallowing: from taste and warmth of the milk; from smell of the milk; from touch of milk dribbling down the chin; from warmth and touch activation from mother’s adjacent body; from the child’s sucking sounds; and from emotions that accompany satiation or hunger. It comes to include patterns of stimuli from position sense — that is, sensory stimuli that signal changes in head, neck, and body position — and any intrapsychic feedback of motor control that directs those changes in head, neck, and body position. The scheme may include patterns of stimuli from the mother’s cooing, and even from ambient light. The sucking scheme includes not only sucking on a nipple, but also sucking on the fingers or thumb, on a block, and so on. When the sucking scheme is active, it is, to a varying extent, all of these many and diverse activations. ³

To repeat: To the infant, this sucking scheme, as global and undifferentiated as it is, is the object. It is the nipple, the breast, or the bottle or sometimes all three.

This is a very strange object, compared to later object schemes. When the infant sucks an object, her sucking scheme is not just the nipple, but also, to a significant extent, the finger and the block. At the same time, it is both the scheme of the object being sucked and the scheme of the self doing the sucking. Note that this self is also an object.

Piaget charted the transformations that such initial undifferentiated object schemes undergo as they become increasingly distinct for different objects, including the self as an object. In stages, these schemes reorganize themselves as they interact with the world (via the sensory end organs and the motor control of behavior of the body) and with each other. They reorganize themselves into distinct schemes of different objects, and into schemes of attributes (e.g. , size, amount, color) of objects. This includes schemes of the self as an object, and schemes of the attributes of the self.

Put another way, from the interaction of such primitive schemes with each other and through sensory and motor contact with the external world (including the social world), the child constructs her particular world, her self, and the attributes of both her self and her world. The early global and undifferentiated scheme is the anlage of self and world — an earlier, more primitive structure that transforms into more sophisticated structures — just as the embryo is the anlage that transforms into a fetus.

Any current pattern of activation that has some past or present relationship to the sucking scheme is nutrient or aliment for the scheme. Such aliment sustains the scheme as food sustains a biological structure. Although a scheme requires aliment for sustenance — that is, maintenance — the scheme does not become the aliment, any more than we become cattle by eating beef. One kind of aliment may be frequently assimilated to a scheme; another kind of aliment may be seldom assimilated to that scheme. The kind of aliment that may sustain a scheme is highly variable. In one child, the sucking scheme is sustained by the sucking of the hand; in another, it is sustained by sucking all of the fingers, and so on. In one child the scheme may be sustained by a propped bottle; in another by a breast. In a specific child, the kind of aliment that will sustain a scheme is, in large measure, unpredictable.

Although the scheme requires aliment for sustenance, it accommodates to nuances of the aliment that it assimilates and is thereby modified. Evidence of accommodation of the sucking scheme is the child’s shaping his or her mouth differently when sucking a nipple than when sucking a finger, or the child’s becoming more skilled at sucking a nipple, a finger, or a block. The sucking scheme accommodates to patterns of differential sensorimotor activation arising from sucking a finger or a block, along with patterns arising from sucking a nipple. When the sucking scheme is next activated, it is ready to assimilate aliment from a finger or a block as well as from a nipple. The scheme has adapted. Through assimilation of aliment and accommodation to aliment, a scheme adapts. "All behavior is adaptation and all adaptation is the establishment of equilibrium between the organism and its environment" (Piaget, 1981b, p. 4). ⁴

Piaget’s pseudodigestive model of the psyche — the way in which the scheme assimilates and accommodates — captures the quality of an active, holistic intrapsychic process. The scheme is active in the sense that it is considerably self-directed. The scheme assimilates at its own organizational level, and allows organizations that are beyond its level to pass it by. Initially, the wooden block or the truck is to suck. Later, the block is to slide and the truck is to roll on the floor. The scheme is holistic. Given a scheme’s level of organization, it assimilates as much and as varied aliment as the current organization can somehow connect to.

The scheme concept provides for the conservation of existing structure, yet allows for the development or modification of that structure. The fact that the scheme is an open system, allows it to be influenced by both the environment and maturation. ⁵

When the young infant sucks an object, her scheme of that object — her object — includes all past and present patterns of motor and sensory activations occasioned by encounters of her mouth with her finger, a nipple, a block, and so on. Her scheme includes any other patterns of activation that were or are cotemporaneous with such encounters — for example, activation patterns from emotions, ⁶ from waking, from sleeping, from warmth, and so on:

During the elementary stages of consciousness things are much less apprehended in their own form than is the case with the adult or child who talks. There is not a thumb, a hand, a ribbon. . . [N]ew objects. . .have no peculiar or separate qualities (Piaget, 1963, p. 141).

The young infant’s scheme is undifferentiated. There is no sharp distinction between subschemes, such as past or present, sucking a block or sucking a finger. The undifferentiation, however, is not absolute. Ordinarily, one does not elicit grasping by stroking the infant’s cheek, or elicit sucking by touching the infant’s palm. There is also some differentiation due to accommodation. The child sucks a nipple differently than she sucks a block or a finger. It is also possible for two schemes — for example, sucking, grasping, and looking schemes — to be simultaneously active, yet not be part of each other. If that is the case, they soon become part of the same scheme, as when the infant brings the hand that grasps to the mouth that sucks, ⁷ or (by leaning forward) brings the mouth that sucks to the hand that is looked at, and so on. In the early stages, almost everything is, to some degree, connected to — is part of — everything else. ⁸

Fundamentally, Piaget’s scheme bonds psychology and psychological development to its biological roots. The newborn’s schemes center on reflexes, and schemes are analogous to biological structures in their function. That is, like biological structures, they assimilate, accommodate, and adapt.

I propose that the operation of Piaget’s scheme may be readily translated into current theory that information, and what to do with information, is stored in the activation of the neuronal circuits of the brain. Piaget never explicitly proposed that a scheme might be identical to the activation of a neuronal circuit, although it is hard to believe that he did not have this in mind. I, and other students of Piaget’s work, believe that the two are identical.

Neuronal Circuits in the Brain

The nervous system is the control system for higher animals. The structural components of this control system are neurons — cells that conduct electrical impulses from one cell to the next. The extension of a neuron that conducts electrical impulses to another neuron is called an axon. The neurons that receive impulses are referred to as being downstream. See Figure 1. Neuron A’s axon conducts impulses downstream to neuron B. Neuron B’s axon conducts impulses downstream to neuron C, and so on. Neuron B is downstream from neuron A. Neuron C is downstream from neurons A and B. Between each pair of neurons is a very small functional gap, the synaptic space. When the electrical impulses reach the end of neuron A’s axon, they cause the release of chemicals called neurotransmitters into the synaptic space. The neurotransmitter chemicals pass to the other side of the synapse, where they are received by receptors on neuron B. These receptors are located either on the surface of the body of neuron B or on extensions of neuron B, called dendrites. If neuron B is in a responsive state when it takes up a sufficient amount of a neurotransmitter, neuron B will transmit electrical impulses down its axon to the synapse between itself and neuron C. Some synapses are inhibitory; if a sufficient amount of a neurotransmitter is released into the synaptic space, the effect will be to inhibit the downstream neuron rather than to excite it.

There are about a hundred billion neurons in the human cerebral cortex and many hundreds of billions of synapses. Hence, there are many, many hundreds of billions of interconnections between the neurons. These interconnections form complex interrelated sets of neurons called neuronal circuits. Many neuroscientists believe that learning — memories and what to do with memories — reside in activations of neuronal circuits. They believe that learning is dependent on the strength of connections between the neurons of interconnecting circuits.

In 1894 Ramon y Cajal proposed that repeated activation of one neuron by another increased the strength of connections between them (Kandel, Schwartz, & Jessel, 2000). Currently this theory is known as the Hebbian hypothesis (Hebb, 1949). The specific mechanisms that explain why activation of a neuron increases that neuron’s responsiveness to reactivation are not entirely settled. Nonetheless, many findings support the hypothesis that electrochemical mechanisms at the synapse account for such responses, and hence account for learning (Brembs et al. , 2002; Kandel, 2004 ⁹; LeDoux, 1996; Rioult-Pedotti, Friedman, & Donoghue, 2000; Shi, 2001). Nothing has been found that contradicts the hypothesis that a neuronal circuit that activates another circuit facilitates subsequent repetition of this same relationship. Huttenlocher and Dabholkar (1997) found that in early life, the cerebral cortex contains an abundance of synapses. This abundance of synapses declines in older children. Loss of synapses that are not activated is another probable mechanism involved in learning. Both the long-term strengthening of a synapse by repeated activation of that synapse and the pruning of synapses that are not used are probably involved in learning — in the consolidation of memories and what to do with memories. ¹⁰, ¹¹

The Neuronal Circuit and the Scheme

According to Piaget, as I explained earlier, the scheme will assimilate to itself any activation that is similar to it. I will propose that this responsiveness of the scheme may be understood as the equivalent of Hebb’s hypothesis that activation of a neuronal circuit increases that circuit’s tendency to be reactivated.

For example, a 7-month-old may repeatedly strike a suspended object with her foot or her arm and watch the object swing. Consider the scheme of that 7-month-old who strikes an object with her foot. The infant’s current striking of the object with a foot and watching the object swing, along with any pleasure that she gets from doing so, is aliment. According to Piaget, this aliment is assimilated to any past similar schemes. For example, it is assimilated to the scheme that includes, at the very least, past motor control of the leg, proprioception from the leg and foot, ¹² touch activation from the foot, visual activation from the retina, proprioception from and control of the eye muscles when watching a similar moving object, and positive emotions. Simply put, a previously active scheme that has some relationship to the present activation is reactivated by the present activation.

Now let us look at this example from a neurophysiological point of view. When the infant strikes an object with her foot, this activates a particular set of sensory and motor neuronal circuits in the brain. Thereafter, each time that she strikes an object with her foot, the neuronal activations that this entails will automatically involve many of the same neuronal circuits that were involved earlier. That is, many of the same circuits that were involved earlier are reactivated. ¹³

According to Hebb’s hypothesis, if many of the same neuronal circuits are reactivated, later reactivation is more likely, because the synapses have been strengthened. Hence it is as if previously activated neuronal circuits assimilate current similar activation. Because previous activation increases the likelihood of reactivation, it is as if the activation were aliment for the circuits. ¹⁴

Reactivation, however, never occurs in exactly the same way twice. This is true even when the infant is striking with the same foot and watching the same object. Thus reactivation could be expected to modify existing neuronal circuits, strengthening some parts of a neuronal circuit more than others. Accordingly, the circuits change a bit. They appear to accommodate, just as Piaget proposed that schemes do. The changed neuronal circuit is then ready to be reactivated by the later activation patterns along with the old pattern. The neuronal circuit — the scheme — has adapted.

Thus, neuronal circuits appear to assimilate aliment, accommodate, and adapt. I see no difference between the activation of neuronal circuits and Piaget’s scheme.

More about Schemes, or the Activation of Neuronal Circuits

A Scheme, Where it is Stored, and How it is Accessed

Although any given type of scheme — for example, the sucking scheme — is similar for all infants, the aliment — the activation of particular circuits — that sustains a scheme varies greatly from infant to infant and varies considerably in each infant from time to time. The aliment that an infant assimilates, the particular neuronal circuitry that is activated by sensorimotor interactions with different objects, depends on an infant’s innate predisposition as well as on his own experiences. The aliment involves many and different sources of activation. Thus its corresponding neuronal circuitry is located in widespread regions of the brain, which may be accessed by many and varied connections.

One infant sucks his thumb, another his entire hand, and so on. One infant is languid. Another is very active. One infant arches his back to cause a mobile attached to the bed to move. Another strikes at the mobile with his foot.

One infant is allowed to suck his thumb. Another is offered a pacifier. One infant is breast-fed; another is bottle-fed. One infant’s bottle is propped up on a pillow. Another’s is held in his mother’s hand. One infant is talked to while feeding. Another is played with. Accordingly, each infant has different aliment for sustenance of his sucking scheme or neuronal circuit. Any one infant may have all of these experiences. Each infant, over time, has different kinds of aliment for sustenance of his sucking scheme or neuronal circuit.

Such differences in predisposition and in environment imply that any given type of scheme is highly variable in content — the aliment that sustains it. Hence the location of a scheme — the activation of its corresponding neuronal circuitry in the brain — varies and is spread across many parts of the brain. This is so from infant to infant, but is also so from one time to the next in each infant. See Figures 2 and 3 for the usual locations of different sensory and motor activations.

In each instance, the components of the sucking scheme include variations in activation of touch, proprioception, motor control, sight, warmth, and so forth. These variations necessarily activate, or are activated by, very different parts of the brain, including very different parts of the cerebral cortex. The sensory areas of the cerebral cortex that responds to touch of the hand (excluding the fingers) and to touch of the fingers are close, but they are not the same. The various motor and sensory regions of the brain that are active when an infant is sucking the breast are vastly different from the regions that are active when an infant is sucking from a bottle that is propped up.

If the aliment that sustains the neuronal circuitry that corresponds to a scheme is variable and widespread, two things follow. First, although to begin with the nucleus for the scheme is a particular reflex, the scheme in its totality is content-addressable. ¹⁵ Current and past aliment, or content, determines the location of neuronal circuit activation. ¹⁶ Second, under different circumstances, reactivation of the neuronal circuitry that corresponds to a scheme may be through components, which may be located in very different parts of the brain. Access to a scheme or reactivation of a scheme may be constructed of different parts from one time to the next.

Here is an example of how neuronal circuits vary from one child to another. At about 3 months, Piaget’s son would grasp an object that he saw, provided that his hand was in view. His sisters did not do this until they were 4 ½ to 6 months old. Piaget proposed that his son’s precocity, compared to his sisters, could be explained by the fact that, before he was 3 months old, he often studied his clasping his hands in front of him. The particular neuronal circuits that must be modified in order for him to learn to grasp an object when both his hand and the object were in view would necessarily be simpler than those of his sisters, who did not engage in the preliminary behavior.

Thelen (1998) and her colleagues traced the steps involved in successfully reaching for a ball. These steps began with the infant’s sight of the ball, which gave rise to mouth movements. She reported that her colleagues, Blass and Jones, found that when an infant’s hand was touched, the infant opened his mouth. They also found that visual stimulation triggered hand movement, mouth movement (as Piaget had discovered earlier), and tongue protrusion. These findings suggest that the newborn’s neuronal circuits are widespread, connecting different sensory and motor systems.

Newborns vary greatly in their activity levels and in the particular kinds of spontaneous activity that they engage in. Like Piaget’s son, some infants tend to study their hands. Others do not. Some infants flail about. Accordingly, the infants in Thelen’s study required very different types of muscular coordination in order to reach for a ball. Yet Thelen found that at about 4 months (12-24 weeks) each child made a successful reaching movement to get the ball and bring it to his mouth. To reach the ball, however clumsily as they did so to begin with, these infants had to modulate their arm movements. Thelen’s associate Spencer charted the infants’ use of different muscles over time. He found no consistency with respect to the muscles that were used in reaching. The only built-in constant involving motor movement of the arm was a relationship of shoulder torque to elbow torque. The outcome — successful reaching for a ball — was the same, but the coordinations involved in getting there were idiosyncratic.

This relationship of shoulder to elbow torque may be a prewired component of the complex achievement of learning to reach for an object. To successfully reach for an object, which coordinates very different neuromuscular combinations — different starting positions of the arms and different speeds of prereaching movements — must be constructed of sensing and control of very different body parts. That is, the sensing and the control activations must be located in different areas of the brain in different infants, and in the same infant at different times.

Brain Modules — Are They Predetermined?

As I noted earlier, not every developmental theorist agrees that we must construct our selves and our world anew. Some theorists propose that differentiations of self, objects and attributes are in place at birth. Others propose that, at appointed times, certain brain regions — modules — are predestined by our genes to generate these differentiations.

There is no doubt that the mature cerebral cortex is to some extent a modular organ; certain functions in the mature brain are space-dedicated to a particular region of the cerebral cortex. In most adults, damage to a particular region of the left cerebral cortical hemisphere — Wernicke’s area — results in impairment in understanding written and spoken language, but no impairment in vision or hearing. Similarly, damage to another region — Broca’s area — in the left cerebral hemisphere results in impairment in speaking and writing, but no impairment in understanding spoken or written language. See Figure 2. Damage to V 1 — the primary visual area — in the left hemisphere will result in blindness in the right half of the visual field. See Figures 2, 4, and 5. Each of these areas of the brain also has its own maturational schedule. Presumably, these schedules are, to a great extent, programmed by genes.

Genes often do not directly determine function. Often genes appear to offer options that may be exercised or not, or that may be exercised differently, depending on other factors. Later in this book, I suggest a type of maturation, which presumably is under the control of the genes and that assists a major social cognitive shift. The maturational factor offers a mechanism for assessing certain options, but it does not determine which social cognitive style — that is, how the person thinks about certain social issues — will be adopted. I will propose that the social cognitive style that is adopted is adaptive for a particular individual in his or her family setting.

There is considerable plasticity in what are usually function-dedicated modules. In adults who were blind from early infancy, visual cortex was activated by reading Braille (Sadato et al. , 1998) and by attention to sounds (Kujala et al. , 1995). In congenitally deaf adults whose primary language is sign language, auditory association cortex was activated by signs for words (Petitto et al. , 2000). Von Melchner, Pallas, and Sur (2000) used a complex surgical protocol that rewired the auditory cortex of newborn ferrets to receive stimuli from the visual tract. When the ferrets were adults, the cellular pattern of their auditory cortex resembled the cellular pattern of visual cortex. Further, the investigators found that, when the visual routes to the cerebral cortex were severed, the ferrets processed visual stimuli using the auditory cortex solely.

In short, modularity appears to be predisposition, not absolute predestination. Modularity is probably the result of a cascade of timed interactions, some of which are genetically triggered, but some of which are dependent on the environment. ¹⁷

Luria’s Functional Modules

Any discussion of brain module function would be incomplete without a reference to Luria’s (1966) localization of cerebral cortical functions. Luria extended the work of his predecessors — Sechenov, Pavlov, and Vigotsky — as he synthesized the findings of many other psychologists and neuroscientists with his extensive and innovative studies of brain-damaged adults, including 800 patients who had suffered gunshot wounds to the head.

Luria distinguished two uses of the term function. One use is exemplified by the statement that the function of the cells of the retina is to respond to light. The second use of function refers to an organism’s complex adaptive activity — for example, locomotion, perception, or cognition. In each instance, the adaptive activity may be done in any one of various ways, the exact way being determined by the organism.

Luria’s studies of the cerebral cortex were aimed at localizing this second type of function. He addressed the localization of three fundamental functional systems or analyzers — the acoustic analyzer, the optic analyzer, and the sensorimotor analyzer. A type of behavior that results from damage to, or electrical stimulation of, a particular area of the cerebral cortex, demonstrates merely that that the behavior is related to that particular area. Luria stressed that the relationship does not demonstrate that control of that behavior resides solely in that particular area. "[F]or a function to be disturbed it is sufficient, in practice, for any one link in a complex functional system to be broken" (p. 70). Similarly, many different sources of activation may ordinarily contribute to the organized control of a particular behavior.

Perhaps Luria’s most striking ideas involved the function of the motor analyzer. He proposed that the core of motor control in the cerebral cortex resides in the coordination of the primary motor area with the primary somatosensory — touch and proprioception — area; that in terms of function, they were a unit. See Figures 2 and 3 for the location of the primary motor and sensory areas, and for the massive association areas, which lay between the primary motor and sensory areas. In the past, because damage to a particular location of the primary motor area resulted in paralysis of a limb, it was thought that motor control of that limb resided in that particular location. Luria marshaled considerable evidence — phylogenetic, developmental, anatomic, lesion, and electrical stimulation studies — to show that the primary motor and somatosensory areas of the cortex are designed to work as a functional unit. For example, simply extending a limb involves proprioception, not just the motor function. If the primary somatosensory area of a limb is damaged, the limb muscles will pull against each other in an uncoordinated fashion. Damage to the somatosensory area of the limb is not confined to loss of sensation from the limb. Luria showed that the motor and sensory association areas of the cortex must work together to organize complex voluntary behavior.

Luria did similar analyses and syntheses of the acoustic analyzer and the optic analyzer, and the ways they overlap with one another and with the motor analyzer. The details of his work, his incorporation of the work of other investigators, and his remarkable synthesis of detailed clinical and experimental findings into holistic concepts are beyond the scope of this presentation. Suffice it to say that Luria’s functional modules of the brain are very large, that they overlap one another, and that they are very much like Piaget’s schemes.

The thesis of this chapter has been that Piaget’s concept of the scheme uses a language that may be translated into the language currently used to explain brain function. I have proposed that the scheme may be seen as identical to the activation of neuronal circuitry.

How is a thought represented in such a system? Freud (1934a) proposed that thinking is an experimental way of acting. According to his theory, thought of an activity would be the moving of objects around in one’s mind, just as one moves furniture around in the physical world. Instead of walking to the fridge and opening the door to get some food, one moves one’s self intrapsychically, crosses the room, opens the door, and so on.

The movement of the self and the door all takes place in one’s mind, rather than in the external world. Thinking is interiorized action. ¹⁸

Information processing of computers reminds us that representations are a function of the medium. Representations do not necessarily resemble that which is represented. In a computer doing word processing, objects such as letters and words, and what-to-do-with-them are just patterns or programs controlling open and closed switches. In the brain, objects, including letters and words, and what-to-do-with-them are probably activations of neuronal circuits and of the interrelationships among those circuits. In keeping with such an understanding, one may think of the intrapsychic movement of an object — that is, of the idea of movement — as an ordered array of changes in neuronal ensembles that occur when an object moves in relation to other objects. In the brain walking to the fridge and so on is a sampling of the many interfaces or relationships between interrelated sets of stimuli from lines and colors of light, from proprioception of muscle and joint movement, from touch of this and that, and so on. Piaget’s constructivist approach lends itself to this kind of unconscious or conscious content — to the concept that the idea of the object and its activity are active by virtue of arrays of definitions of relationships between this object and other objects, present and past. These arrays of definitions may be grouped. But their grouping need not resemble the form of a body moving to the fridge.

In the next chapter, I review the first four stages of Piaget’s Sensorimotor Period. During the Sensorimotor Period, undifferentiated schemes transform themselves into increasingly differentiated schemes as different objects. As I review the first four sensorimotor stages, I will propose how maturation of a sensory tract probably assists the differentiation of schemes as different objects. My proposal explains how a kind of brain maturation affects cognitive development. I will also remind the reader what an object is like at each stage. In chapters 3 and 4, I will show how an examination of the sensorimotor stages of development may clarify the relationship of mind to brain.

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