He is best known for his work in rehabilitation following traumatic brain injury (TBI) and other forms of acquired neurological impairment. His two major contributions to TBI rehabilitation are the Neuro-functional Approach to brain injury rehabilitation (with J. Clark-Wilson) which is a client-centered, goal-driven approach that incorporates the principles of skill learning and promotes the development of routines and competencies in practical activities required for everyday living.
The second is non-aversive treatment of persons with neurobehavioral disability and behavior disorder; sometimes referred to as relational therapy.
The interventions stress a philosophy of normalization, respect, non-confrontation, positive engagement, support, and functional and behavioral skill development. The approach is based on the observation that much of the behavioral disregulation is hostile/irritable aggression and not instrumental in nature. The interventions attempt to reduce environmental stressors and instigations to aggression and to use inclusion and positive engagement to reduce the frequency of aggressive behavior.