Effects of ambient stimuli on measures of behavioral state and microswitch use in adults with profound multiple impairments.

Three adults with profound multiple impairments sat in a room while researchers changed the sights and sounds around them. One condition had colorful posters and upbeat music. Another had no extra visuals or sounds. A third mixed both types of stimuli.

Each person wore a microswitch. A small finger or head movement closed the circuit and turned on a brief favorite video or tune. The team counted how often the adults hit the switch and rated their alertness during each condition.

Switch hits went up or down depending on the room condition, but the changes did not follow the same pattern for everyone. One adult pressed most when music filled the room. Another peaked during the mixed-stimulus block. The third showed only small shifts.

Alertness scores, however, barely moved. High or low switch rates did not line up with higher or lower awake-looking behavior for any participant.

Smith et al. (2010) gave post-coma adults the power to choose and replay their own stimuli. Those participants hit their switches far more when the click led to a preferred clip, showing clear stimulus control. The 2004 adults could not choose; the room simply played stimuli. Choice may be the key ingredient.

Van Hanegem et al. (2014) used switch presses to turn on preferred stimuli and taught head rolls or proper steps. Their participants kept the new motor skills, proving the contingency can drive learning. The 2004 study only watched incidental pressing, so no skill was targeted and no lasting change occurred.

Together the papers draw a straight line: microswitch activation rises when the press produces a chosen or needed event, not when stimuli are just there.

Before you record baseline data, scan the room. Posters, music, or a noisy hallway can raise or lower switch hits, so keep the setup the same across sessions. If you want more than random pressing, let the client choose or request the stimulus. Choice turns ambient noise into real reinforcement.