Questions answered with the pupils of your eyes (w/ Video)

This is a still frame, depicting essentially the final frame of the movie, only that in the upper right the computation is still depicted. Credit: Current Biology, Stoll et al.

Patients who are otherwise completely unable to communicate can answer yes or no questions within seconds with the help of a simple system—consisting of just a laptop and camera—that measures nothing but the size of their pupils. The tool, described and demonstrated in Current Biology, a Cell Press publication, on August 5 takes advantage of changes in pupil size that naturally occur when people do mental arithmetic. It requires no specialized equipment or training at all.

The new pupil response system might not only help those who are severely motor-impaired communicate, but might also be extended to assessing the mental state of patients whose state of consciousness is unclear, the researchers say.

"It is remarkable that a as simple as the pupil has such a rich repertoire of responses that it can be used for a task as complex as communication," says Wolfgang Einhäuser of Philipps-Universität Marburg in Germany.

The researchers asked healthy people to solve a only when the correct answer to a yes or no question was shown to them on a screen. The mental load associated with solving that problem caused an automatic increase in pupil size, which the researchers showed they could measure and translate into an accurate answer to questions like "Are you 20 years old?"

They then tested out their pupil response algorithm on seven "typical" locked-in patients who had suffered following a stroke. In many cases, they were able to discern an answer based on pupil size alone.

"We find it remarkable that the system worked almost perfectly in all healthy and then could be transferred directly from them to the patients, with no need for training or parameter adjustment," Einhäuser says.

This video is not supported by your browser at this time.

While the system could still use improvement in terms of speed and accuracy, those are technical hurdles Einhäuser is confident they can readily overcome. Their measures of pupil response could already make an important difference for those who need it most.

"For patients with altered state of consciousness—those who are in a coma or other unresponsive state—any communication is a big step forward," he says.

More information: Current Biology Vol 23 No 15

add to favorites email to friend print save as pdf

Related Stories

Pupil Dilation Marks Decision Making

Feb 13, 2008

The eyes may be the windows to the soul, but the simple pupil--the circular opening at the center of the eye that contracts and dilates to regulate the amount of light the eye receives--offers a remarkable portal to the inner ...

The pupils are the windows to the mind

Jan 28, 2012

The eyes are the window into the soul -- or at least the mind, according to a new paper published in Perspectives on Psychological Science, a journal of the Association for Psychological Science. Measuring the diameter of the ...

Recommended for you

Know the brain, and its axons, by the clothes they wear

Apr 18, 2014

(Medical Xpress)—It is widely know that the grey matter of the brain is grey because it is dense with cell bodies and capillaries. The white matter is almost entirely composed of lipid-based myelin, but ...

Turning off depression in the brain

Apr 17, 2014

Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain's reward circuit and experimentally reversed it – but there's ...

Rapid whole-brain imaging with single cell resolution

Apr 17, 2014

A major challenge of systems biology is understanding how phenomena at the cellular scale correlate with activity at the organism level. A concerted effort has been made especially in the brain, as scientists are aiming to ...

User comments