Sigelman, C., K., de George, L., Cunial, K., & Rider, E. A. (2019). Life span human development (3rd ed.). Cengage Learning Australia Pty Ltd.
As you saw in Chapter 1, development results from a complex interplay of nature and nurture where both forces ‘co-act’ to produce development. Some theorists, however, have taken different positions on the issue. Strong believers in nature have stressed the importance of individual genetic makeup, universal maturational processes guided by genes, and biologically-based predispositions built into genes over the course of evolution. Such theorists have been likely to claim that child-ren typically achieve the same developmental milestones at similar times because of maturational forces, that major changes associated with ageing are largely biologically based, and that differences among children or adults are largely because of differences in genetic makeup and physiology.
By contrast, strong believers in nurture emphasise environment or influences from outside the person. Nurture includes influences of the physical environment (crowding, pollution and the like) as well as the social environment (for example, learning experiences, child-rearing methods, peers, societal trends such as social media, and the cultural context in which the person develops). A strong believer in the influence of nurture is likely to argue that human development can take many paths depending on the individual’s experiences over a lifetime.
The activity-passivity issue focuses on the extent to which human beings are active in creating and influencing their own environments and, in the process, producing their own development; or are passively shaped by forces beyond their control. Some theorists focus on humans as curious, active creatures who orchestrate their own development by exploring the world around them and shaping their environments. Both the budding scientist who experiments with chemicals in the backyard and the sociable adolescent who spends hours text messaging or on social media are seeking out and actively creating a ‘niche’ that suits their emerging traits and abilities – and that further develops those traits in the process (Plomin et al., 2013).
Other theorists view humans as more passive in their development, being shaped largely by forces beyond their control – usually environmental influences but possibly strong biological forces too. From this vantage point, children’s academic failings might be blamed on the failure of their parents and teachers to provide them with the ‘right’ learning experiences, and the problems of socially isolated older adults might be attributed to societal neglect of the elderly or inevitable biological processes of ageing.
Another developmental issue of interest to theorists is the extent to which the changes people undergo over the life span are gradual or abrupt. Continuity theorists view human development as a process that occurs in small steps, without sudden changes, as when children gradually gain weight from year to year. In contrast, discontinuity theorists tend to picture the course of development as more like a series of stair steps, each of which elevates the individual to a new (and often more advanced) level of functioning. When an adolescent boy rapidly shoots up 15 centimetres in height, gains a bass voice and grows a beard, the change seems discontinuous.
Theorists have also been interested in whether changes are quantitative or qualitative in nature. Quantitative changes are changes in degree and indicate continuity: a person gains more wrinkles, grows taller, knows more vocabulary words or interacts with friends less frequently. By contrast, qualitative changes are changes in kind and suggest discontinuity. They are changes that make the individual fundamentally different in some way. The transformation of a tadpole into a frog rather than just a bigger tadpole; of a non-verbal infant into a speaking toddler; or of a pre-pubertal child into a sexually mature adolescent are examples of qualitative changes (and see Figure 2.2).
So continuity theorists typically argue that developmental changes are gradual and quantitative, whereas discontinuity theorists hold that they are more abrupt and qualitative. Discontinuity theorists often propose that people progress through developmental stages. A stage is a distinct phase of development characterised by a particular set of abilities, motives, emotions or behaviours that form a coherent pattern. Development is said to involve fairly rapid transitions from one stage to another, each stage being qualitatively different from the stage before or the stage after. Thus, the adolescent may be able to grasp abstract concepts like human rights and justice in a way that the school-aged child cannot, or the middle-aged adult may be said to be concerned with fundamentally different life issues or conflicts than the young adult or older adult.
Finally, developmental theorists may vary in their position on whether developmental changes are common to all humans (universal) or different across cultures, subcultures, communities, families and individuals (context specific). Discontinuity theorists typically believe that the stages they propose are universal. For example, a stage theorist might claim that virtually all children enter a new stage in their intellectual development as they enter adolescence, or that most adults, sometime around age 40, experience a midlife crisis in which they raise major questions about their lives. From this perspective, development proceeds in certain universal directions.
But other theorists take the position that human development is far more varied and diverse because it is influenced by contextual factors. For example, cross-cultural researchers have found that paths of development followed in one culture may be quite different from paths followed in another culture, and may even differ from subcultural group to subcultural group, from neighbourhood to neighbourhood, from family to family and from individual to individual. Review the On the internet: Cross-cultural psychology link to learn more about the influence of culture on development. There seems to be both universality and context specificity in human development. As poet Mark Van Doren once said, ‘There are two statements about human beings that are true: that all human beings are alike, and that all are different’ (cited in Norenzayan & Heine, 2005, p. 763).
FIGURE 2.2 Development is both continuous and discontinuous
Development involves quantitative changes, becoming different in degree (as shown in Panel A, with a size increase), and qualitative changes, becoming different in kind (as shown in Panel B, where a tadpole becomes a frog).
