Attractor dimensions of behavior state changes among individuals with profound disabilities.

Accumulating evidence indicates that many physiological and psychological processes behave in nonlinear ways, and some developmental researchers have recommended that behavior states should also be investigated within this framework. We examined state transitions for evidence of nonlinearity among 66 subjects with profound disabilities. States were observed during continuous periods of 5 hours for each subject. Data were analyzed as percentage time subjects spent in various states, influence of environmental variables, and evidence of nonlinear state transitions. Twenty of three subjects demonstrated chaotic state trajectories, but there appeared to be no observed characteristics that differentiated them from other participants. Findings suggest complex behavioral processes in the levels of alertness and responsiveness associated with some individuals with profound disabilities. Implications for other populations and physiological measures were discussed.