Ecological Systems Theory

Ecological Systems Theory was developed in the 1970s by Russian-American psychologist Urie Bronfenbrenner (1917–2005) as a reaction to what he saw as the artificial and limited clinical studies of the time. He was influenced by earlier studies, particularly those done by researchers in Berlin in 1870 on the effects of a child's neighborhood on their development.

Rather than studying subjects in isolated clinical research environments, Bronfenbrenner emphasized the importance of taking a holistic approach by observing individuals’ behavior and development in the context of the their lives, environments, families, and surroundings.

Bronfenbrenner believed that in order to understand human development one must have an understanding of the entire system in which an individual's growth takes place. He organized this environmental system into five subsystems: (1) the microsystem, (2) the mesosystem, (3) the exosystem, (4) the chrono-system, and (5) the macrosystem. He describes these systems as being nested inside each other like Russian nesting dolls.

The microsystem is the closest and most influential subsystem in an individual's development. It refers to the direct relationships between the individual and the immediate environment, such as home, school, and work (or the laboratory or testing room in the case of research). Microsystems are not independent, but rather interconnected and influence each other.

The exosystem is similar to the mesosystem in that it comprises the interactions between two or more settings; however, in this case at least one of the settings does not contain the developing individual, but rather indirectly influences the developing individual—for example, the relation between a child's home environment and the parent's workplace. If a parent loses a job, this loss will have an effect on the child even though the child is not a direct participant in the workplace environment.

The macrosystem refers to the larger, overarching cultural patterns and factors such as the economy and material resources, belief systems, customs, political systems, and life opportunities.

The chronosystem represents the changes (or lack thereof) an individual experiences over time, both personally and with regards to the environment and the relationship time has to a person's development. It can refer to the effect of a child growing up at a particular time in history such as during the Great Depression or a time of war. It may also refer to the time at which traumatic life events take place, such as the age of an individual when a loved one dies.

Ecological Systems Theory encourages social workers to take a holistic view of clients' situations, so that they may address the individuals as well as the clients' surrounding systems. However, critics of the theory have pointed out its limitations. Although it is a model used by social workers to describe and explain or better understand clients’ lives and situations, it does not prescribe specific interventions.

In later years, Bronfenbrenner expanded his Ecological Systems Theory to create the Bioecological model, which he introduced in 1994. This model places more focus on the individual and the genetic component of development and the concept of gene-environment (i.e. nature-nurture) interactions and the importance of what he calls proximal processes. Proximal processes are reciprocal interactions that take place at the microsystem level (with people, symbols, or objects in the immediate environment such as between parent and child), through which genotypes become phenotypes. Bronfenbrenner saw these proximal processes as the principle mechanism of an individual's development.

He also emphasized that while their environments affect individuals, individuals also affect their environments, so that individuals and systems are interacting constantly.

See also Nature-nurture contraversy.