Measurements in the Impairment: The Sensory Challenge protocol is a laboratory paradigm in which the child's physiologic reactivity after sensation is tested using electrodermal reactivity and vagal tone indices to assess sympathetic and parasympathetic systems. Measurements of functional limitations include aggression, withdrawal, impulsivity, hyperactivity, inattention, and sensitivity to tactile, movement, taste, smell, auditory and visual stimuli. These are measured in the areas: (1) attention (subscales of the parent-report Child Behavior Checklist [CBCL],and Leiter International Performance Scale-Revised; the Continuous Performance Task, the StopTask and the Go-No Go Task); (2) emotion (the CBCL); (3) sensation (the Short Sensory Profile; the Leiter-R; the Multidimensional Anxiety Scale for Children; the Stop Task; the Go-No-Go Task; the Auditory Continuous Performance Test). Measures of the Disability Dimension include the Vineland Scales of Adaptive Behavior, the Goal Attainment Scale, and play and dinner-time paradigms. Finally, measures in Societal Limitations Dimension include a parent semi-structured interview and the Visual Analogue Scale.