General Developmental Theories-Ecological Theory
Ecological theory evolved from the recognition that even though the environment has a major effect on development, many models of development have limited generalizability across contexts. Consider, for example, classic studies by Tulkin and his colleagues on the effect of mother-infant interaction patterns on the infant’s development of language and mental abilities. This effect is stronger among socioeconomic middle-class families than among lower-class families. Likewise, Scarr has found that the magnitude of genetic influences on intellectual development varies according to the cultural group being studied. Greater genetic effects are observed in middle-class white groups than in lower-class African-American groups. Among lower-class families, different influences on development are operating. Findings such as these led ecological theorists such as Lewin, Bronfenbrenner, and Barker to conclude that models of development are bounded by the context in which they are framed.
Ecological theory suggests that process models of development have no universality; rather, they must be framed within the limits of a cultural and historical context. This theory must be distinguished from the radical postmodernist perspective that scientific principles have no objective basis. Ecological theorists conceptualize the environment systematically and attempt to understand how it affects development.
Bronfenbrenner has articulated an ecological model that includes developmental influences at the individual (person), person-by-environment (process), and context levels. He categorizes contextual settings into three types: microsystems, mesosystems, and exosystems. As discussed earlier in this chapter, the most proximal type is the microsystem, which includes one’s immediate physical and social environment. Examples of microsystems are homes, schools, playgrounds, and work places. Each microsystem has a structure and a set of rules and norms for behavior that are fairly consistent across time. Developmental scientists study processes within each of these settings, and ecologists warn them not to overgeneralize process phenomena from one microsystem to another.
The next type is the mesosystem, which is defined as a combination of microsystems that leads to a new level of developmental influence. For example, in understanding the effects of parental versus peer influences on adolescent development, one must consider not only each of the family and peer microsystems but also the effect of the combined mesosystem, that is, the effect of the conflict between the family’s values and the peer group’s values on the child’s development.
The final type is the exosystem, a combination of multiple mesosystems. Research on the effects of maternal employment on child development has been enhanced by an understanding of this exosystem. That is, in order to understand how maternal employment affects a child’s social development, one must understand not only the family and work context but also the cultural and historical context of women’s employment.
Applications of the Theory
Ecological theory has led clinicians to question the generalizability of their practices across cultural, gender, and ethnic groups. Group-specific interventions are being developed. Ecological theory has also led to policy changes in the funding of research at the federal level, in that large research studies are now required to address questions of generalizability across groups. Finally, ecological theorists have pressed cli-nicians to consider the possibility that interventions at a broader level might exert a powerful effect at the microsystem level.
Criticisms of the Theory
Ecological theory is not a theory in the formal sense. Rather, it is a structured framework for identifying influences at numerous levels. Thus it is not falsifiable. Its value is in alerting clinicians to factors that otherwise might be neglected.
Synthesis: Diathesis-Stress Models & Other Interactionist Theories
It has been increasingly recognized that interactionist models of development apply to most forms of psychopathology. These models focus on the confluence of forces that must coalesce in order for a disorder to develop. The most basic of these models is the diathesis-stress model. A diathesis is a dispositional characteristic that predisposes an individual to disorder. The disposition may be biological (as in a genetic predisposition for schizophrenia), environmental (as in poverty), or cognitive (as in low IQ). Disorder is probabilistically related to the presence of a diathesis, but the process of development of psychopathology requires that the individual with the diathesis also be exposed to a stressor, which, again, might be biological or environmental. Only those individuals with both the diathesis and the stressor are likely to develop the disorder.
Consider the diathesis-stress model of major depressive disorder. According to this model, individuals who display the cognitive diathesis of self-blame for failure are at risk for the development of depression, but only if they subsequently experience a stressor that is linked to the diathesis (such as failure). Statistically, this model hypothesizes an interaction effect, and it has been supported for a variety of problems, from depression to physical illness.
Theorists have noted that individual and environmental factors interact not only in static models such as the case of major depressive disorder but also over time in transactional models. These models articulate the reciprocal influences between person and environment and the unfolding of disorder across experience. Finally, theorists have come to recognize that the unfolding occurs in nonlinear, nonuniform ways that lead to qualitative changes in the individual, as in dynamic systems (see the “Major Principles of Ontogeny and Phylogeny” section earlier in this chapter). Dynamic systems models are being borrowed from phenomena in physics to describe the development of novel behaviors in infancy (such as the onset of locomotion and language) and have the potential to be applied to the development of novel deviant behavior in psychopathology.