Objective: To develop a method for establishing the presence of command- following in individuals with traumatic brain injury, based on the principles of single-subject experimental design. Design: A series of single-subject experiments, individualized to the particular command-following question about a particular patient. Setting: An inpatient rehabilitation hospital with a specialized program for vegetative and minimally conscious brain injured patients. Patients: Eight individuals with serious brain injury of traumatic or nontraumatic origin, presenting in vegetative or minimally conscious states. Interventions: The frequency of performance of the behavior in question was assessed in response to commands and in relation to appropriate control conditions. Data were analyzed with χ2 or Fisher's exact test, as well as measures derived from signal detection theory. Main Outcome Measures: The frequency of performance of a specific behavior in the presence of a command and in relevant contrasting conditions. Results: This method identified whether a specific behavior was being performed in response to command and whether the reliability of this behavior was changing over time either spontaneously or in response to treatment. Conclusions: Quantitative assessment of command-following based on principles of single- subject experimental design can determine whether patients are capable of following commands and whether this ability changes over time or in response to treatment.
Whyte, J., DiPasquale, M. C., & Vaccaro, M. (1999). Assessment of command-following in minimally conscious brain injured patients. Archives of Physical Medicine and Rehabilitation, 80(6), 653–660. https://doi.org/10.1016/S0003-9993(99)90168-5