Nonlinear dynamic relationships between functional behavior and symptomatology in people with chronic psychosis.

摘要

Nonlinear dynamic systems theory, sometimes called chaos theory, represents a significant advance in ways of thinking about causality. Chaos theory posits that complex behavior can result from nonlinear relationships between just a few variables. Some have suggested that a nonlinear approach might be fruitful in the study of human behavior, particularly to the study of various aspects of psychopathology. The present study examines how application of nonlinear dynamic systems theory might illuminate the relationship between functional behavior and symptomatology in people with chronic psychosis. 13 male inpatients were selected from a pool of archival longitudinal data. These data were collected some time prior to the era of deinstitutionalization; all 13 subjects were diagnosed with dementia praecox. The data were part of an original study examining the effect of a one-minute, variable-interval reinforcement schedule on operant conditioning in people with chronic psychosis. Subjects participated in experimental sessions in which they operated a manipulandum to receive reinforcements. Data were also collected on the number of vocalizations made by each subject. Vocalizations, not necessary to the task, were assumed to be an index of symptomatology. In the present study, the time series data on operant responses and vocalizations were examined using nonlinear dynamic systems analysis (NDSA) techniques. Attractors were reconstructed from the time series data and various mathematical indices were calculated to assess whether nonlinearity was present. The results of these analyses were compared to exemplar data sets. Inter-subject comparisons were also made. The results suggest that operant responses and vocalizations represent a nonlinear system that is controlled by two factors: one which causes these behaviors to increase and another, which causes them to decrease. These findings have significant implications for our ability to predict and affect the course of both functional behavior and symptomatology in people with chronic psychosis. Although application of chaos theory to problems in psychology is in its infancy, the results suggest that such applications may provide-new insights into complex human behavior.