Researchers from CNRS / Aix-Marseille University (France) and Utrecht University (Netherlands) have developed a way to—literally—write text by thinking of letters. In this technique, several letters are presented on a computer screen. The color of these letters continuously changes from white to black and back again, in different patterns. When participants direct their attention to one of these letters (without looking at it) the size of the pupil starts to reflect the size of the attended letter: The pupil becomes larger when the letter is black, and smaller when the letter is white (just like your pupil shrinks when you look directly at a bright light). By measuring these small changes in pupil size, the researchers were able to find out which letters the participants were attending to; as a result, the participants were able to write letters by merely attending to them, without moving any part of their body, including the eyes.
This technique could be important, because it could provide a way for completely paralyzed people to communicate. This is already possible with other techniques, but these require elaborate and expensive equipment to record brain signals. Measuring the size of the pupil is much easier and cheaper than measuring brain signals, and this new technique may therefore bring communication within reach of more paralyzed people. However, this is still a work progress; so far, the new technique has only been tested with healthy participants, and whether it will also work with paralyzed people remains to be demonstrated.
Source: Mathôt, S., Melmi, J.-B, van der Linden, L., & Van der Stigchel, S. (2016). The mind-writing pupil: A human-computer interface based on decoding of attention through pupillometry. PloS ONE. http://doi.org/journal.pone.0148805
Note: The manuscript will become published on-line on Friday, February 4th