Since the mid 1970s, medical personnel have used the Glasgow Coma Scale (GCS) as an important tool to rate and describe levels of consciousness. This scale is rudimentary and subjective, often resulting in misdiagnoses in cases where people lack the capacity to communicate. In some unfortunate situations, severe neurological damage can render people unable to move. Inevitably, these people are deemed vegetative when in actuality; many are simply locked in. For years researchers have used cognitive event related potentials (ERPs) with modified EEG to assess receptive language capacity.