For people with locked-in syndrome, communication is pretty much impossible. The condition results in paralysis from head to toe and is usually due to a stroke or an injury to the brainstem or lower brain.
But while these patients can't move or talk, their eyes usually remain active and their upper brains retain full cognitive function. Researchers have now come up with a novel way to allow patients to answer yes or no questions by intentionally dilating their pupils.
The size of a person's pupil changes in response to light, but there are also subtler, internal cues that cause it to change. Emotionally arousing events are know to dilate pupils, as does the brain power used in decision-making. In this study, the researchers used mental math as a way for participants to control their pupil size to answer yes or no questions. For each trial, a participant sat in front ...
