Individual Differences in Life-Span Development

Two Major Approaches to Development

Traditionally, there have been two major approaches to the study of development, a norm-based approach investigating differences between groups who differ primarily on the basis of age and an individual difference–based approach examining how characteristics of individuals and their environment affect outcomes over the life course. Historically, the field of developmental psychology has placed a greater emphasis on documenting age-group differences that provide important information about normative aspects of development.

This approach has been useful for establishing age-based norms for a wide range of behaviors, including cognitive functioning, language acquisition, and motor development. However, this approach is not very helpful for determining why individuals vary from the norms and processes that underlie developmental change. Further, this approach does not generally provide much information about how one might create interventions to aid individuals who fall outside the norm on some measure.

In addition, the approach can lead to the reification of milestones, reinforcing an assumption that developmental timing and processes are [Page 1124]highly uniform across individuals and groups. This view of milestones leads to a tendency to ignore or underestimate variability that has been found in the timing and pattern of acquisition of various behaviors. Variability from the norm, especially in terms of lags in the timing of milestone achievement, is viewed more from a disease model, with lags labeled as developmental delays rather than as typical variation around a norm.

In contrast, an individual difference approach to development can help identify factors that influence developmental outcomes, provide insight in to developmental processes, and offer guidance to researchers and practitioners interested in establishing effective interventions. A key characteristic of research from an individual difference approach is that researchers often use individual differences on variables of interest as predictors of specific positive or negative outcomes. The benefits of an individual differences approach, however, must be viewed in light of greater cost in time and resources. This approach generally requires a relatively large number of participants to examine key research questions and sophisticated statistical techniques to process the data.

Individual Differences in EF

EF refers to a set of domain general control processes, such as the ability to direct attention and use information in memory to make decisions and guide behavior. EF plays an important role in a large number of developmental outcomes, including academic achievement and physical health. Deficits in EF have been found to be linked to attention-deficit/hyperactivity disorder and autism spectrum disorder.

Cross-sectional research on EF has documented a mostly linear increase in EF from early childhood (age 3 years) up through adolescence. In contrast, an individual difference approach to EF enables researchers to more closely examine whether EF is stable across development and whether EF might be improved through interventions. Individual differences in EF have been found to be predictive of improvements in children’s understanding that people can hold beliefs that are false.

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