In some cases it is the stimulation that the family provides that may actually be the factor that brings the person out. Often the stimulus that makes a difference and elicits a response is something familiar. However, a totally new type of stimulation may get their attention better. It is a matter of trying different things.
Some responses are very basic reflexes.
At the other extreme are behaviors such as complex conversations. Lights or objects that the person can see are another type. Familiar odors or different kinds of touch are also used. Vestibular therapy involves moving the person around passively. This provides touch as well as vestibular or positions sensation.