Operant procedures and the comatose patient.

Operant procedures were tested on three patients who had been in vegetative coma for 6 months, 10 months, and 38 months. A discrete trial procedure was used to test compliance to verbal requests for three behaviors for each patient, including lateral head movement or finger movement, eye focus or eye squeeze, and mouth movement. The design for each patient consisted of multiple baselines across three behaviors with a withdrawal phase and a reinstatement phase (ABAB) for one behavior. Baseline phases were followed by contingent music phases in which 15-second taped excerpts of patients' preferred music sounded immediately following the emission of targeted behaviors. The contingent music treatment affected all three behaviors for Patient 1, but was less effective for two out of three behaviors for the second and third patients who had been in coma for more extensive periods of time. Results are discussed in terms of the potential contributions of the use of operant assessment and treatment procedures in an area of medicine where they have not been used before.