Researchers at Philipps-Universitat Marburg in Germany have managed to teach brain damaged patients who are 'locked in' to communicate using their eye pupils.
Healthy pupils automatically dilate, or increase in size, when faced with a challenging task, such as solving a mathematical puzzle. The researchers exploited this fact by first asking a group of healthy volunteers to solve a mathematical puzzle only when a correct answer to a yes-no question was shown.
They found that the eye pupils of the volunteers can be observed to identify whether the right answer was given. On testing the scenario among seven locked-in patients, who were brain damaged and not able to move or talk, the researchers found that the answers to the questions could be found out through pupil size.
"It is remarkable that a physiological system as simple as the pupil has such a rich repertoire of responses that it can be used for a task as complex as communication. We find it remarkable that the system worked almost perfectly in all healthy observers and then could be transferred directly from them to the patients, with no need for training or parameter adjustment", lead researcher Professor Wolfgang Einhauser said.