I've recently encountered an interesting account of development called 'Dynamic Systems Theory'. I found it reading Linda Smith and Esther Thelen's 2003 publication of 'Development as a dynamic system' 1 Its a very fascinating explanation at the age-old developmental question (no pun intended), how does something as incredible and complex as the human mind emerge from what seems to be a helpless, unformed infant? To put in another way, what allows something as intricate as the human psyche emerge from something as ostensibly rudimentary as the mind of an infant.
Its really a harder question to answer than one might assume. I myself have taken this fundamental phenomenon for granted in my observation of development. I have understood development to be a process where biologically predetermined capacities, such as capacities for language, for speaking, etc., emerge in a sequential fashion according during our lifespan. This perspective makes sense, it accounts for the emergence of incredibly complex traits as well as answers the question as to why so many universal human qualities exist; because they are genetically endowed upon our species. I have almost taken this account without question, but he problem with this perspective is that is undermines, and entirely removes the influence of experience; it categorizes development as an unstoppable force not to be altered or halted for any reason, in this case, experience. It may seem obvious that humans do not exist in a small bubble, that is human have experiences, but it is a relatively unheard-of proposal to say that specific experiences actually change our development. In fact, much of developmental psychology and medicine insists that our development is entirely maturation, with our biologically determined bodies moving in an interactive environment.
This is the subject of this paper, and of much of the debate in developmental psychology: What part of our developmental is due to biological maturation, aka the emergence of predisposed dispositions, and what part of our development should be attributed to the influence of experience; the take on the classic nature versus nurture debate. Although much of our development seems uniform across individuals, there is a large amount between humans that seems to vary. For instance, levels of nourishment seem to make a difference, varying socioeconomic statuses seem to make a difference in cognitive capabilities, and so on. The authors of this article propose that the developmental similarities across individuals globally, although robust, seems to be more complicated and less determined when one gets down to the intricacies of human qualities. For this reason, Smith and Thelen propose that development is characterized best as a complex system, composed of many subsystems, embedded within, and interacting with a dynamic environment. Their answer to the nature nurture question is that although phylogenic, biological constraints seem to guide development, they do not exist as predetermined structures simply emerging as one ages; instead many complex systems within the human interact with one another, as well as with the environment, in sometimes predictable and unpredictable ways to produce emergent capacities. In this way, Thelen and Smith hope to account for the perceived similarities within the human race, as well as its seemingly obvious variation.
Let me explain that the issue is not simply a nurture versus nature argument, and that my ability to properly describe it is insufficient. I have not spent enough time with this literature to really understand the intricacies of the debate. But perhaps with my explanation of this theory, and future explanations of opposing and facilitating theories, a better explanation will emerge. I am still on my way to understanding the big question driving developmental theory. I will again emphasize that my understanding in this area is limited, but I will do my best to present in a comprehensible fashion. Anyway, back to dynamic systems theory.
The theory that Thelan and Smith present is known as dynamic systems theory. As before mentioned, the dynamic systems that they are referring to are found in the body in the form of self-organizing skills and capacities, being dynamic in that they are ever-changing and always exposed to a changing environment. I will explain the implications of the view of development by explaining the two major tenets of their theory: first that developmental processes are not causally set in stone, the concept of Multicausality, and second that the many systems that we are composed of exist in varying speeds, a concept they call Nested Timescales. After explaining these core concepts of the theory a better picture of dynamic systems will emerge.
The first concept of Multicausality deals with the multiple ways in which organisms create coherent behavior and novelty. As the name implies, the idea of multicausality is the idea that many coherent structures that we perceive in humans (e.g. language use) do not emerge from a single causal system. The tenet proposes that these structure can emerge in a multitude of ways. This is stated because dynamic systems theory views organisms as being comprised of a multitude of different parts and systems constantly rearranging themselves into coherent, and most of the time incoherent, manners. Development then can be classified as a process that constantly producing behaviors and processes that will vary in the level stability, making some last longer and remain more constant than others, the stable formations, and some emergent qualities shorter, the less stable. This is how they account for the emergence of all different behaviors and qualities found in development. This explanation is in contrast to the explanation the development consists of predetermined biological structures emerging as one matures in a predictable linear fashion. Smith and Thelan's theory gives a much less deterministic account of development than the traditional maturational viewpoint, emphasizing the non-linear nature of development. I find this view fascinating and holding much truth, that we exist as a collaborations of numerous complex systems, but the question of how humans end up being so similar is still looming. The next tenet of the theory attempts to answer this question more fully.
The second tenet of dynamic systems theory is that behavioral change occurs over different timescales nested within each other. I've been throwing around the jargon 'nested timescales' for a little bit now and would like to apologize for its ambiguity–I will explain what I mean by in this context right now. Developmental systems (speaking of jargon) refer to any process or classification of development. For instance, a system could be learning development, it could be motorical development, it could be neural. All of these systems are comprised of subsystems and function is accordance and interaction to all other systems as well. The terminology of nested timescales alludes to the fact that many of these system vary in their times of action, for instance, neural action can take milliseconds, whereas other systems of development, such as learning, take years. The core message is that these systems do not function separately, but instead interact with one another, 'nesting' into all other timescales. It is lengthy, but Smith and Thelan in an eloquent fashion, beautifully depict this fundamental concept:
Traditionally, psychologists have considered action, learning, development
and evolution as distinct processes. But for the organism (and its
descendants), time is unified and coherent, as are the collaborating elements
of the system. Every neural event is the initial condition for the next
slice of time. Every cell division sets the stage for the next. The coherence
of time and levels of the complex system mean that the dynamics of one
time-scale (e.g. neural activity) must be continuous with and nested within the
dynamics of all other time-scales (e.g. growth, learning and development).
Thus, in the study of development, we must be concerned with how
different timescales interact. (344)
All processes, from the most minute cellular process, to the most complex behavioral patterns and rules are all interconnected and influenced by one another. All processes depend on the infinite multitude of other processes that also exist in the larger system. The interaction between dynamic systems is actually specified by the author as a process categorized by circular causality. The microscopic properties of an organism set the stage for that organism's behavior and macroscopic interactions, they provide the necessary backdrop for an organism to exist in an environment. On the flip side, the macroscopic behavioral interactions that the organism is having, according to the authors, also has an influence–they set the conditions for the functioning microscopic processes. In this way all processes are the product of behaviors effecting biological development and biological development effect behavioral. An example of this interaction could be in the emotional response that we so often go through. To pull apart the experience, you are having millisecond biological responses in the form of chemical adjustments and muscular variations during the response, as well as the feeling of the 'actual' emotion you are feeling. These two interacting domains allow the organism to constantly 'reorganize' its behavioral systems. make sense? cool right?
At first this may seem obvious: of course all processes in the body interact with one another during development, after all, they do literally all exist in a singular entity. But at the same time, to make the connection between the smallest of infinite biological processes and the most complex psychological is, to me, mind boggling. It seems to crystallize the notion that development is indeed infinitely complex.
In their article the next step that they take is to examine the classic developmental task, 'A not B', and see if the results seem to correlate with their proposed dynamic systems approach. To quickly sum and not bore you with great detail and care that they take in their assessment, I will report the important findings. To review, the 'A not B' task involves showing the baby a toy. The toy is then put underneath one of two boxes, A or B. The experimenter puts the toy repeatedly under box A and then has the baby repeatedly locate the toy under box A. The critical trial of the procedure involves the experimenter placing the toy underneath box B, then asking the infant to locate the toy. Well, it ends up that there are certain times when the baby will choose the first box, and certain times when the baby will choose the second box, the box where the toy is now hidden.
What the researchers emphasize in their unique take on this classic test is the multitude of ways in which performance can be facilitated. The experimenters use a mechanism that lets them assess the neural activity of the baby as well as cameras that detect the eye movement of the baby, to combine with data on the actual choice that the infant makes. The results that they found were presented in a manner that allowed them to compare the neural flux's relation to the choices that the infants' made. They found this to be a valuable comparison because it would allow them to have a converging set of data that suggests how the baby is attending to the task at hand (fyi infant attention is a huge topic in this lab and in the field of development psychology that I will be discussing at length in the future). Having multiple methods of assessing infant attention provided researchers with a better ability to try and pick apart what the infant was actually thinking during the choosing process, a difficult question to answer, but a crucial one in understanding the differences in performance for failing infants and successful infants in the 'A not B' examination.
What the researchers found was that there were a multitude of factors that influenced the performance of the baby, not the just its conditioned response to the A box. Behavioralism, the psychology of the 20th century, predicted that the only changing variable during the experiment was the the level of conditioning that the baby encountered. The researcher accounted for this variable by recording the number of initial 'hides' under box A before the critical phase moving the toy under box B. The number of times the box was initially hidden under A did end up making a significant difference, but surprisingly so did many other factors. They found that changing the delay between hiding the toy under box B and asking the infant to locate it also made a difference. Through measuring the neural activity of the infant they were able to see peaking interest in their attention of Box B (a rough estimate of attention) and found that the infant focused on the box, but only for a short time. They found that there was a duration of time after hiding the toy under box B where if they asked the infant to locate the toy they would do it correctly. They also found that this time period, where the infant would be successful at locating the toy, was influenced by the number of times that the toy had been placed under box A. The strength of the cue towards box B rapidly diminished as the number of times the boy had been placed under box A increased, but, their always remained a period where the infant could understand that the toy was under B. They also found that success at the task was also influenced by the attention-grabbing properties of the of the boxes and the hiding event, as well as the posture/physical condition of the infant (the importance of this physical adjustment is a focus of the lab that I'm working in and I will discuss it later). These taken together make the explanation that the only occurring process is one of conditioning seem too simple.
Finding these multiple causes for success at the 'A not B' experiment supports the author's hypothesis that all developmental processes are complicated involved a wide range of systems. Observing the many factors that seem to be at work suggests the complexity of any tasks that we do, a main point that the authors of this article are trying to make. They wanted to expose the concept that tasks are not singular developments, but are the emerging product of many interacting systems. Thinking of development in this way makes the primary question in the 'A not B' experiment switch from, "what do 10-month olds who are successful at the task know that infants who are unable to successfully complete task do not?" This has been the manner in which the 'A not B' experiment has been approached, but Smith and Thelan want to stress that a more complex approach should be taken.
Smith and Thelan's Dynamic Systems Theory moves the approach not from trying to understand static abilities at any one point in time during development to understanding the multitude of dynamic systems involved in development. Their concept of multicausality changes the notion of knowledge from single emergent quality to a set of contributing dynamic systems varying in their stability throughout development. So, instead of trying to understand when infants gain a knowledge of the a not b task, instead we should be trying to understand the task's multicausal nature. In this way the author's believe that a better picture of what is actually occurring during development will result. The dynamic systems theoretical approach then aims to understand the multitude of processes existing in varying timescales embedded with one dynamic, constantly reorganizing organism.
Looking at this theory has been valuable for me and my conception of development. Although after talking to one of the graduate students in the lab informed me that this particular take on development is not the one with which the lab entirely works under, it is close, and many of the concepts of reorganization and embedded systems development are very important to understand entering the world of infant psychology. This was good to hear, and daunting. The emphasis of the lab I am working in is the interaction of these complex systems with the environment and how specific experiences impact the complex systems in the organism. So, I'm glad I stumbled upon this article, and hope my explanation of it is intelligible. I will elaborate on the specifics of the lab that I am working in in the future, although understanding the 'systems approach' will be important in my further journey into what this lab is actually dealing with. I'm excited.
1. Smith, L.B., Thelen, E. (2003). Development as a dynamic system. TRENDS in Cognitive Sciences, 7, 343-378.
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