Developmental domains

By studying how humans change and grow from conception through childhood, adolescence, adulthood, and death, developmental psychologists try to answer questions around the differences between a child and their growth into an adult, and the influence of the childhood experience.

Developmental psychologists view development as a lifelong process that can be studied scientifically across three developmental domains of:

Physical development, involving growth and changes in the body and brain, the senses, motor skills, and health and wellness.

Cognitive development, involving learning, attention, memory, language, thinking, reasoning, and creativity.

Psychosocial development, involving emotions, personality, and social relationships.

Research methods in human development

Developmental psychologists use many of these approaches in order to better understand how individuals change mentally and physically over time. These methods include naturalistic observations, case studies, surveys, and experiments, among others.

Naturalistic observations

Naturalistic observations involve observing behaviour in its natural context. A developmental psychologist might observe how children behave on a playground, at a daycare centre, or in the child's own home. While this research approach provides a glimpse into how children behave in their natural settings, researchers have very little control over the types and/or frequencies of displayed behaviour.

Case studies

In a case study, developmental psychologists collect a great deal of information from one individual in order to better understand physical and psychological changes over the lifespan. This particular approach is an excellent way to better understand individuals, who are exceptional in some way, but it is especially prone to researcher bias in interpretation, and it is difficult to generalise conclusions to the larger population.

In one classic example of this research method being applied to a study of lifespan development Sigmund Freud analysed the development of a child known as 'Little Hans'. Freud's findings helped inform his theories of psychosexual development in children.

Another example would be how psychologists examine developmental milestones through detailed research on a single individual. In one child's case, their neglectful and abusive upbringing led to them to being unable to speak until, at age 13, they were removed from that harmful environment.

As the child learned to use language, psychologists were able to compare how the child's language acquisition abilities differed when occurring in their late-stage development compared to the typical acquisition of those skills during the ages of infancy through early childhood.

Surveys

The survey method asks individuals to self-report important information about their thoughts, experiences, and beliefs. This particular method can provide large amounts of information in relatively short amounts of time. However, validity of data collected in this way relies on honest self-reporting, and the data is relatively shallow when compared to the depth of information collected in a case study.

Experiments

Experiments involve significant control over extraneous variables and manipulation of the independent variable, a variable that is changed by the researcher or scientist. As such, experimental research allows developmental psychologists to make causal statements about certain variables that are important for the developmental process.

Because experimental research must occur in a controlled environment, researchers must be cautious about whether behaviors observed in the laboratory translate to an individual's natural environment.

The normative approach

Across the domains of physical, cognitive, and psychosocial, the normative approach to development is also considered by psychologists. In the early decades of the 20th century, normative psychologists studied large numbers of children at various ages to determine norms (i.e., average ages) of when most children reach specific developmental milestones in each of the three domains.

Although children develop at slightly different rates, we can use these age-related averages as general guidelines to compare children with same-age peers to determine the approximate ages they should reach specific normative events called developmental milestones (e.g., crawling, walking, writing, dressing, naming colors, speaking in sentences, and starting puberty).

Not all normative events are universal, meaning they are not experienced by all individuals across all cultures. Biological milestones, such as puberty, tend to be universal, but social milestones, such as the age when children begin formal schooling, are not necessarily universal; instead, they affect most individuals in a particular culture.

For example, in developed countries children begin school around 5 or 6 years of age, but in developing countries, like Nigeria, children often enter school at an advanced age, if at all.

Talking point

In the Comments, consider sharing with other learners your thoughts on the following:

To better understand the normative approach, imagine two new mothers, Louisa and Kimberly, who are close friends and have children around the same age. Louisa's daughter is 14 months old, and Kimberly's son is 12 months old.

According to the normative approach, the average age a child starts to walk is 12 months. However, at 14 months Louisa's daughter still isn't walking. She tells Kimberly she is worried that something might be wrong with her baby. Kimberly is surprised because her son started walking when he was only 10 months old.

Should Louisa be worried?

Should she be concerned if her daughter is not walking by 15 months or 18 months?