Tess Lefmann & Terri Combs-Orme. Journal of Human Behavior in the Social Environment. Volume 23, Issue 5. July/August 2013.
Despite social work’s claim of a bio-psychosocial approach to human behavior and development, the profession fails to incorporate important physiological knowledge into practice, research, and education. This article provides an example of the usefulness of understanding the ontology of early brain development by demonstrating how such knowledge can be integrated into Piaget’s theory of cognitive development. We suggest that social work’s focus on evidence-based practice demands the incorporation of neuroscience into the profession’s body of knowledge.
Social work lacks an ontogenetic view of development, encompassing development from a single cell through every stage to death. Despite growing knowledge in neuroscience and genetics to inform such an ontogenetic view, a strong biological component has yet to be incorporated into social work practice, research, or education. This is especially troubling given the current emphasis on evidence-based practice. Other fields, such as psychology have recognized that evidence-based practice must be based on the most up-to-date science about human biology, whereas social work has yet to heed Saleeby’s (1992) call of 20 years ago to incorporate biology into the professional knowledge base.
Instead, social work has emphasized classic stage models of development in human behavior in the social environment (HBSE) coursework content (see any textbook on HBSE). Such models describe (but do not explain) development as a sequence of stages wherein specific developmental tasks (behaviors) are mastered in sequence; individuals who fail to satisfactorily complete one stage are expected to experience difficulties successfully achieving subsequent stages. HBSE courses in social work typically feature the models of Erikson, Vygotsky, Piaget, and others, though little attention has been paid to linking such theories directly to social work practice, and those links are far from obvious.
We suggest that as a transition to a more scientific approach that heeds Saleeby’s (1992) call, stage models may easily be integrated with important knowledge about brain development to enrich the content and make it more useful to social work. As an example of how this integration might be accomplished, this paper overlays the early biological development of the brain with Piaget’s sensorimotor stage of development.
Piaget’s Cognitive Developmental Theory
Piaget came to the study of psychology through his search for how knowledge developed in the human child. With a degree in the natural sciences and zoology, he entered the field primed with a developmental and genetic perspective. After conducting many studies using traditional methods of data collection, Piaget sought to elicit more genuine responses in children, thus changing his methods to a less guided form of research that combined naturalistic observation, psychometrics, and the psychiatric clinical examination. The synthesis of these methods was used to observe how children responded to and articulated certain situations with their own reasoning as a way of examining their thought processes. The results formed the stages of development within Piaget’s theory. Like Freud, Piaget believed that development of the structures of the brain is key to the developmental tasks he described, but too little was known at the time, and technology was inadequate to explore and demonstrate those connections. “Every psychological explanation comes sooner or later to biology or logic …” Piaget said in 1950 (p. 3).
Piaget’s four major stages are the sensorimotor period (birth to age 2); the preoperational thought period (about age 2 to age 7); the concrete-operations period (about age 7 to age 11); and the formal operations period (about age 11 to age 15). Piaget (1973) stated that “there is a constant order of succession … that is, in order to reach a certain stage, previous steps must be taken … thus we reach a hierarchy of mental structures which are built in a certain order of integration” (pp. 10-11). In this explanation, we see foreshadowing of scientific descriptions of the development of the brain: from the bottom up, and from the inside out, from simple automatic functions such as breathing, to the more complex, up to higher-order reasoning and problem solving.
Neuroscience research in the last two decades calls attention to the enormous impact of experience and the environment on infant development and the foundational nature of this stage for the entire life course. For this reason, this paper focuses on Piaget’s earliest (sensorimotor) period of development and the associated maturational changes in the brain.
Piaget’s Sensorimotor Period
The study of infancy proved to be challenging for Piaget, as he was of course unable to rely on language as a tool for understanding infants’ inner processes. However, his belief in development as a universal process (a belief that is tempered now by an understanding of how culture interacts with physiology to influence development) allowed him the freedom to observe small sample sizes, mainly his three children. Although Piaget usually did not describe his methods, we know that he differentiated the sub-stages within the sensorimotor period based on “interventions” shaped by Piaget and his wife, such as rearranging objects within a room and assessing the children’s reactions.
The period from birth to age 2 may be the most dynamic and important phase of brain development in humans, and it is certainly fascinating. Key maturational events put elementary cognitive processes in place that then allow for the development of abstract thought, planning, and cognitive flexibility as observed by Piaget. Piaget’s observations of children between birth and 2 two led to his differentiation of six sub-stages within the sensorimotor period, during which children’s learning is based on movement and the five senses.
Stage 1: Birth to 1 Month
At birth, the brain weighs only about 25% of the adult brain, but in the first 3 years of life, it will grow to 90% of adult weight, chiefly through the development of wiring and connections. Three key processes during this time drive the growth: dendritic arborization, synaptogenesis, and myelination. Dendritic arborization is the branching out of dendrites, connections that reach the axons of other neurons and begin transmitting messages from neuron to neuron, putting into motion the communication between neurons that is the basis of brain functioning. Functioning of the brain occurs in the connections among neurons, as chemical substances or neurotransmitters excite or inhibit the firing of the neurons.
Piaget’s first stage emphasizes action through reflexive actions , including sucking objects, following moving or interesting objects with the eyes, and closing the hand when objects make contact with the palm. The child is learning about his or her world through the senses. Piaget’s focus on the sensorimotor is appropriate to what is occurring in the brain in these early days. During the first 5 weeks of rapid development, glucose uptake, the brain’s energy metabolism, is highest in the sensorimotor cortex, thalamus, brainstem, and cerebellar vermis. These areas, together, form a section of the basic motor pathway of the primary motor cortex, which is responsible for generating the neural impulses controlling the execution of movement.
The process of building connections among neurons, called synaptogenesis, is the basis of learning. In this first month of life, the infant is learning to track objects and then to reach for them, for example, by repeatedly practicing and building synapses in the parts of the brain that process and connect visual and motor behavior. The phrase Neurons that fire together, wire together is an expression of this fact: Repeated signaling builds and strengthens connections among the neurons; this is the essence of learning. The infant’s early movements and exploration build as many as 40,000 synapses per second through the first year of life.
The behavioral systems that function early in development described by Piaget show the earliest pattern of myelination. Myelination is the process through which the myelin sheath, formed of lipids (fats) and proteins, is developed and wrapped around axons to increase the speed at which impulses are transmitted between neurons. It can be compared to the insulation on electrical wires; without that insulation, messages between the neurons would be inefficient and slow. Early in the first year, movements are jerky and automatic but, over the four sub-stages in the first year, become more coordinated and intentional. Improved myelination is critical to this refinement of movement.
Benes, Turtle, Khan, and Farol (1994) found that the pathway that carries information about the visual tracking of moving objects and the ability to coordinate movements of the eyes, head, neck, and trunk (the rhombencephalic portion of the medial longitudinal fasciculus) is one of the earliest central nervous system tracts to myelinate, allowing the infant’s early sucking, grasping, and following objects described by Piaget, as myelination improves signaling and the infant’s accuracy in tracking and grasping.
Stage 2: 1 to 4 Months
Piaget’s second sub-stage of the sensorimotor period describes primary circular reactions, which are basically new habits (repetitive actions) and accommodations based on learning (1963). For example, when a child systematically sucks his or her thumb, no longer due to chance contact but by coordinating his or her hand and mouth, Piaget referred to this as acquired accommodation (Piaget). We also may call this learning. Repeated action improves the infant’s ability to act intentionally.
Vision is not well developed at birth (a fact almost universally acknowledged as new parents hold their newborns close to their faces to establish eye contact), but the visual cortex and synaptogenesis in that area develop rapidly between the second and fourth postnatal months. This rapid development in vision corresponds with Piaget’s observations of the infant’s ability to coordinate actions such as sucking his or her thumb, thus allowing for new levels of learning. As his or her vision improves, for example, he or she becomes more competent at reaching for and grasping specific objects he or she wants.
Using magnetic resonance imaging, Barkovich, Kjos, Jackson, and Norman (1988) found increases in signal intensity of white matter in infants by 4 months. White matter, which consists of myelinated axons, facilitates communication among different parts of the brain. The posterior portion of the corpus callosum (called the splenium) communicates somatosensory information between the two halves of the parietal lobe and the visual center of the occipital lobe during this time. The greater the communication among brain regions, the more competent the infant is at integrating motor, sensory, and cognitive information, the very skills Piaget described.
Stage 3: 4 to 8 Months
Piaget’s third stage focuses on secondary circular reactions, which mark the beginning of the infant’s ability to distinguish between iself and the outside environment. Piaget described the difference between primary and secondary circular reactions as being about intention. Primary circular reactions in sub-stage 2 are simple organic movements just for the sake of movement, while secondary reactions are centered on creating a result in the external environment. Again, we see how learning occurs through repetition; the infant is learning that he or she can take specific actions that cause specific effects.
This learning corresponds to completion of dendritic arborization (laying down of the connections) in the hippocampus, the brain region most associated with learning and memory. Also about this time, the cerebellum, which is involved in motor coordination and balance, has more than doubled in size. This remarkable growth supports the rapid motor development during infancy and the intentional movement that the infant is beginning to use to influence his or her environment.
Stage 4: 8 to 12 Months
Piaget’s fourth sub-stage focuses on emergence of practical intelligence: envisioning goals or desired ends and then employing existing schemes to achieve the ends. Such activities are evidence of the brain’s executive functions (planning and carrying out plans), and are supported by the frontal cortex, which plays a crucial role in higher-order cognition. Not coincidentally, the frontal cortex is dramatically increasing its synaptic density at this time.
Gains in neuromuscular functioning are occurring rapidly during this time, too, supported by completion of dendritic arborization in the previous sub-stage, as myelination of the corticospinal tract reaches mature levels in the brain stem by about 1 year and in the spinal cord by about 28 months. As neuromuscular functioning improves, the infant becomes ever better at carrying out his or her goal of banging on his or her high chair with a spoon to make noise or throwing his or her bottle to get Mom and Dad to react.
And last, during this fourth stage (between 8 and 12 months), the frontal, parietal, and occipital lobes continue myelination, furthering the development of sensory systems and conscious thought. Soon the infant will be able to plan and carry out a series of actions to get what he or she wants more effectively.
Stage 5: 12 to 18 Months
Piaget’s (1963) fifth sub-stage focuses on tertiary circular reactions, in which the 1-year-old experiments to find out how things are new. For example, the infant has discovered that banging a spoon on his or her high chair makes a satisfying noise; will banging the spoon on the wall do that, too? How about filling the spoon with beets and banging the spoon on the wall? This action also creates a satisfying visual display!
Key to this stage is the development of object relations, meaning the way children conceive of themselves in relation to the objects of the world as well as the way they see objects’ relationships to one another. The idea of object permanence, the understanding that objects continue to exist even when they cannot be seen, heard, or touched, is a key component of object relations and believed by Piaget to be a big cognitive breakthrough for the child. This is the beginning of conceptual thinking; the infant can think about his or her ball, even when his or her ball cannot be seen.
Diamond (1990) demonstrated that the maturation of the dorsolateral prefrontal cortex (DLPFC) is associated with successful performance in the object retrieval task, a test demonstrating object permanence. In this task, the DLPFC is the highest cortical area responsible for motor planning, organization, and regulation, and according to Diamond, plays an important role in integrating both the inhibitory skills necessary to prevent the infant reaching to the wrong hiding place and for remembering where the object was hidden.
The caudate nucleus of the basal ganglia also increases in volume during this time. The caudate nucleus is crucial for the control of movement, suggesting that its growth relates to an increase in motor development. It is not coincidental that most infants begin to walk during this time, as they now have an understanding that they can move from one place to another as well as control their muscles and legs to do so.
Stage 6: 18 to 24 Months
The final stage of Piaget’s sensorimotor period is marked by the beginning of insight and creativity, ushering the way into Piaget’s preoperational thought period, when children become increasingly adept at using symbols, as seen in the increase in playing and pretending, for example “riding” a stick and pretending it is a horse. Piaget emphasized that by repeating this inventiveness across a wide range of objects and actions, children construct new ways of dealing with objects and new knowledge about objects themselves, thus forming “reflective intelligence”.
The infant also shows an increasing ability to voluntarily initiate and suppress behavior, demonstrating a key component of this operational stage. In humans, development of this skill is promoted by maturation of integrated functioning (connections) among higher parts of the brain: the neocortex, striatum, thalamus, and cerebellum.
By the time the infant is 2 years of age, his or her total brain volume (number, size, and density of neurons and glia as well as dendritic and axonal number and density) is about 83% of adult size. Most of that growth is in the first year, as the brain increases about 101%, compared to 15% in the second year.
However, brain size is only part of maturation. Synaptic pruning, the loss of synapses, is also important for enhancing widely distributed brain functions by refining synaptic connections and enhancing rapid transfer of information throughout the brain. Increasing cognitive capacity during childhood, thus, corresponds with a gradual loss, rather than constant formation, of new synapses and presumably a strengthening of remaining synaptic connections. This fact harkens back to “Neurons that fire together, wire together.” Synapses that are not reinforced by experience are pruned back.
Importance to Social Work Practice, Research, and Education
How does understanding how the brain develops better our understanding of behavior and, in particular, development? Casey et al. (2000) proposed that understanding where in the brain a particular function resides helps constrain our theories and models of behavior.
Understanding the function of the brain, thus, has applications not just to theory but to practice, research, and education in social work. Understanding how the brain develops in infancy and connecting ontogeny with functioning helps social workers understand the tremendous importance of infancy for brain development and future functioning and achievement.
Application to Practice
Infancy is not a period that is well represented in the social work knowledge base, despite the fact that many (if not most) of the problems in which social workers intervene arguably have roots in this period of life. Enhanced understanding of the importance of infancy through integration of neuroscience content should provide social workers with knowledge to influence social policy and service design and delivery.
Based on Shonkoff and Phillips’s (2000) compilation of research about early brain development, we have within our reach a number of avenues for enhancing early brain development and, in so doing, enriching the lives of individuals and improving our society overall.
Knickmeyer et al. (2008) state that although the first year of life is a period of developmental vulnerability, it may also be a period in which therapeutic interventions could have the greatest positive effect. Understanding of the ontogeny of brain development during this time provides a better basis for identifying children at risk for developmental disorders than simple observations of infant skills. Such understanding is also more useful for the initiation of appropriate interventions (Knickmeyer et al.).
The maturation of certain key regions of the brain can also be used to establish milestones for normal development, which can be useful for better understanding of parenting “best practices.” Infants rely on their caregivers for the provision and regulation of interactive and other stimuli. As a result, the quality of a child’s caregiving experiences influences the neuronal wiring and development of the brain. Indeed, research on attachment theory and neuroscience has begun to merge, as science comes to understand how early parenting and relationships contribute to the development of the brain. Social work practitioners should be well versed in this environmental interaction so that knowledge can be passed on to parents and communities appropriately and effectively.
For example, the Urban Child Institute (UCI) in Memphis, Tennessee, is a large nonprofit organization whose goal is to raise awareness about and improve early brain development in Memphis. The UCI promotes social policy (e.g., universal pre-kindergarten), sponsors research, and maintains a constant program of public education and training of professionals in the needs of young children. Partnerships with service providers integrate knowledge of early brain development into various types of interventions located in diverse locations. (See www.theurbanchildinstitute.org)
With some exceptions, social work has yet to integrate neuroscience knowledge into social work practice, but this application is crucial to the further development of evidence-based practice.
Application to Research
Recent advances in cognitive neuroscience have allowed researchers to investigate the structure and function of the infant brain. However, few studies or articles have examined the intersection between brain and behavior over the first few years of life or attempted to synthesize the research on human neural development. Indeed, DiPietro (2000) has emphasized the failure to link brain development and behavior more closely. This burgeoning knowledge base should be incorporated into and furthered by the social work research agenda so that we can establish a fully comprehensive bio-psychosocial assessment of human development (a perspective long claimed by the profession).
Increasingly, it is clear that biology must be an important component of understanding human behavior as well as behavior change. For example, evidence suggests that effective cognitive behavior therapy results in part from altering neural pathways. Social work is at risk of falling behind other professions if we do not incorporate biology into intervention research.
Application to Education
Biological components of bio-psychosocial development addressed in courses in HBSE are inadequate and in some cases misleading (Combs-Orme, 2012). With advances into the ontogeny of human behavior, it is necessary to incorporate this knowledge into the social work curriculum. It is time to recognize that courses in HBSE cannot review and evaluate every theory and framework of human behavior that has ever been advanced in order to focus on scientifically valid and heuristic knowledge that can more fully inform complex social work practice.