1.1 Development: A Wider View

How do we explain development? The familiarity of changes we see in infancy and childhood, such as learning to walk or speak, can make this question seem easier to answer than it is. An introductory psychology textbook will usually take you through these changes by age, from prenatal development to adolescence, and set out the influences on physical, cognitive, social and emotional growth. What it often won’t give you is a wider view of how these changes come about, and of why each individual follows a distinctive path while broadly similar patterns keep recurring. This reading begins to build that view, which will take shape over the full resource of About Development.

Watch different babies over the first year and you see recognizably similar things happen. This is particularly clear in motor development, including the ability to reach for and grasp objects. Reaches toward objects that were initially unsteady become more controlled, and the hand begins to adjust to the size and shape of an object before contact. Whole-hand grasps are joined by more differentiated uses of the fingers, and for smaller objects, eventually by a precision grasp between the thumb and index finger (Butterworth et al., 1997). The individual paths taken vary from one infant to another, but the broad pattern is familiar. Across these and other domains, it can seem almost as if each infant is taking the leading role in a show we have seen before: a different actor, but a recognizable part.

That familiarity makes development easy to take for granted, and perhaps questionable as a research topic. Grasping seems to emerge because that is what infants do: it just happens. Same with walking, and language. Research on these topics can seem more justifiable if we connect it to atypical development or to problems that infants and families might have. But this gets things the wrong way round: we cannot fully understand atypical development without understanding the developmental process itself (Karmiloff-Smith, 1998).

Perhaps because it is broadly so dependable, the reliability of development is easy to observe but very difficult to explain. It looks straightforward because we already know roughly what will happen next, and that knowledge belongs to us as observers. We can read an end point (such as precision grasping) back into an earlier stage of development and treat it as an outcome, but that end point is not encoded anywhere.

A common misconception is that outcomes or instructions can be located in the genes. Yes, DNA is important, but it does not contain a specification of the organism or a context-independent set of instructions for constructing it (see DNA as a Developmental Resource).

So we can’t point to genetics alone to explain the reliability of development. Nor can we point to evolution as a simple explanation of why development reliably produces broadly similar forms. Natural selection can help explain why a developmental system that reliably builds a particular kind of body has persisted over generations, but it doesn’t tell us how that body gets built again in each individual (see Evolution and Development).

The reliability of development is one part of the puzzle, but individual variability is just as important: no two individuals are the same. Infants and children reach similar capacities at different ages and by different routes. Their activity can also look quite different along the way, even as familiar patterns recur. A developmental explanation has to account for both the reliability and variability that we see.

When we explain the variability between individuals, we usually talk about genes, experience, culture, or context as influences on development. But that can leave us listing factors and saying that they “interact”, without getting much closer to how development itself works. It also splits the explanatory work: some kind of biological maturation explains what is reliable, and experience, context, and genetic differences explain how individuals differ. But as we will see, the reliable pattern and the individual differences come out of the same developmental process (Gottlieb, 2007).

What Counts as Development?

Development involves change, but not every change is developmental. A crystal grows, but we would not say that it develops. Even developmental biologists find development hard to define (Pradeu et al. 2016). The question is what kind of change counts as development. An infant may miss a toy on one reach and get it on the next, adjusting to what just happened. Someone learning a new skill may likewise alter a movement from one attempt to the next. Such adjustments are important, and they can accumulate, but whether the change is developmental depends on what has changed.

Staying with the example of grasping, the difference becomes easier to see. Over the first year, the infant is not simply practicing the same action over and over and getting better at it. The growing body makes new postures possible. Vision and movement become related in new ways, and experience with objects changes what the infant encounters next. Sitting more stably also changes the conditions for reaching (Rachwani et al., 2015). And the hand begins to take shape in relation to the object before it arrives. Earlier reaching and grasping activity contributes to these changes, but the result is not simply building on a larger collection of successful reaches. The infant making the next reach is no longer reaching from the same starting point.

To unpack this, we can think about the notion of organization, which is used here in a broad sense to mean relations among parts and processes that make a difference to what the system as a whole can do. A bicycle, for example, can be ridden because its wheels, pedals, chain, and frame are related in a particular way i.e., they are organized in a certain way.

A developing organism differs from a bicycle because its organization is not fixed by assembly: it changes as the organism grows and acts. The development of grasping is therefore not located in the hand alone, or in any one part of the infant considered separately. It concerns how the infant’s changing body and activity come to work together, as when sitting more stably allows a different kind of reach.

Development can change the organization from which further activity begins: What has already happened can therefore become part of the conditions for what can happen next. That helps distinguish a developmental history from a mere sequence through time. Toss a coin ten times, and those ten outcomes belong to the history of the sequence, but they do not alter the probability of the next toss.

Not every earlier event leaves a lasting mark, and later outcomes need not trace back to single experiences. But development carries its history forward in a way the coin cannot, because the individual itself has changed. The coin is the same coin on every toss, but the infant is not the same infant from one month to the next.

Seeing Development Backward

The regularity of development creates a particular problem for anyone trying to study it. As observers we know what usually happens later, and the developing infant does not. We already know that most infants will walk, and that grasping will usually come to include a precision grasp. That knowledge gives us a useful reference point for describing earlier changes, but it can also mislead.

If we are interested in the emergence of the precision grasp, we can ask when the thumb and index finger begin to take on differentiated roles, or whether earlier hand configurations resemble the later form. Comparing infants’ trajectories over time can help us ask what predicts earlier or later emergence. Nothing is inherently wrong with doing this. The later state provides a coordinate system for making sense of a complicated history.

But once the later state becomes the reference point, earlier activity can start to look as though it was directed toward that state all along. A hand configuration becomes a precursor because we know what came after it, and a child becomes an adult in the making. Crawling, for instance, is easy to see as a step on the way to walking. Yet a crawling infant is not trying to walk. In retrospect, a developmental pathway can look more inevitable than it did while it was unfolding.

At any moment, development proceeds from what has already developed and from the circumstances in which the individual is acting, not from where it will end up. That is an odd thing to hold on to when the end point is so familiar, and it makes the reliability of development harder to explain, not easier: if the outcome is not there at the start, how does development arrive at it so dependably?

A Wider View

In psychology, development usually means change across infancy, childhood, adolescence and adulthood. In About Development we build on that approach but take a wider view. An infant does not begin from nowhere. The body, the brain, the surroundings in which development takes place, and the practices of other people all have histories of their own. How far across these different histories does an explanation need to go, and how are questions at different timescales related?

Other questions arise when you take this wider view. One concerns direction. Looking at whole life cycles makes it harder to treat adulthood as the finished form that gives meaning to everything before it, while still leaving us with the fact that developmental processes have order and direction.

Another concerns origins: the kind of developmental process we usually take for granted had to become possible at all. A multicellular body is itself something that has to be constructed in every life cycle, through processes whose organization has an evolutionary history.

Seen this way, the ordinary facts of development open onto a much larger set of questions. Why does development recur with such reliability? What gives it direction? How is a history carried forward in a changing individual? And how did the processes capable of producing an organized individual arise in the first place? We cannot fully answer all of these questions, but once they have been asked, it becomes much harder to say that development just happens.

Sources

Butterworth, G., Verweij, E., & Hopkins, B. (1997). The development of prehension in infants: Halverson revisited. British Journal of Developmental Psychology, 15(2), 223–236. https://doi.org/10.1111/j.2044-835X.1997.tb00736.x

Gottlieb, G. (2007). Probabilistic epigenesis. Developmental Science, 10(1), 1–11. https://doi.org/10.1111/j.1467-7687.2007.00556.x

Karmiloff-Smith, A. (1998). Development itself is the key to understanding developmental disorders. Trends in Cognitive Sciences, 2(10), 389–398. https://doi.org/10.1016/S1364-6613(98)01230-3

Pradeu, T., Laplane, L., Prevot, K., Hoquet, T., Reynaud, V., Fusco, G., Minelli, A., Orgogozo, V., & Vervoort, M. (2016). Defining “development.” Current Topics in Developmental Biology, 117, 171–183. https://doi.org/10.1016/bs.ctdb.2015.10.012

Rachwani, J., Santamaria, V., Saavedra, S. L., & Woollacott, M. H. (2015). The development of trunk control and its relation to reaching in infancy: A longitudinal study. Frontiers in Human Neuroscience, 9, Article 94. https://doi.org/10.3389/fnhum.2015.00094

Explore Further

Witherington, D. C., & Boom, J. (2019). Conceptualizing the dynamics of development in the 21st century: Process, (inter)action, and complexity. Human Development, 63(3–4), 147–152. https://doi.org/10.1159/000504097

A short conceptual introduction to a view of development that pays particular attention to the emergence of new organization.