Tobias Loetsher of the University of Melbourne, Australia, and his colleagues from University Hospital Zurich were able to use eye position to predict the size of the next number in a series of randomly chosen numbers.
The researchers asked 12 right-handed men to generate a random list of forty numbers from 1 to 30 while being paced by an electronic metronome. The volunteers’ eye movements were carefully recorded, and the spoken list was synchronized with those eye movements.
It turned out that the subjects routinely looked leftward and downward when the subsequent number chosen was smaller, but rightward and upward if the next number was larger. Not only that, but the degree of eye movement correlated with the size of the numerical shift.
The left versus right glances correspond to the usual placement of numbers on a number line. Therefore, the authors speculate that the brain’s ‘random number generator’ uses real world cues.So, next time you ask someone to pick a random number, consider having her choose two numbers in rapid succession, the second of which will count. Then watch the person’s eye movement. Of course, you’ll have to employ some pretty quick eye movements of your own. In this study, the eye movement occurred only 500 milliseconds before the number was spoken.