The effectiveness of a hands-free environmental control system for the profoundly disabled

To investigate the effectiveness of a hands-free environmental control system (ECS) that allows profoundly disabled persons to activate and control electric devices in their home by using consciously controlled changes in their brain signals.

A cohort study with a field trial testing of the ECS on 3 occasions.

Participants' homes.

Ten profoundly disabled persons (mean age, 42.9 y), all of whom had very limited movement from the neck downward. Six had spinal cord injury with lesions ranging from C2 to C5-6. The other 4 had profound disability (1 each from polio, spinal muscular atrophy, multiple sclerosis, cerebral palsy).

Participants performed tasks on each of 3 test occasions. The tasks consisted of turning a television on at the beginning of the trial, changing channels (up, down), changing volume, and turning it off at the conclusion of each trial.

Time participants took to select the correct option and number of errors made in selecting the correct option. Measures were taken for each trial, so that any improvement in switching could be detected.

All participants effectively used the ECS to operate their television sets. Selecting a correct option took about 30 seconds (with the majority of this time attributed to machine cycling time), with an error rate of 1.8 per 5 options selected. The time taken to operate the ECS reduced slightly over the 3 trials and selection errors reduced by around 50% (to less than 1 error per 5 options).

With minimal training, profoundly disabled persons were able to use an ECS that uses changes in brain wave signals. This result demonstrates the efficacy of an additional and novel ECS in an area in which few switches are available.