Courtesy of the
University of Melbourne
and World Science staff
It may be harder to lie about your age, or your poker hand, after new research has found that our eye position betrays the numbers we’re thinking about.
Participants in a University of Melbourne, Australia, study were asked to state a series of random numbers. By measuring their eye position, researchers said they could reliably predict the next chosen number—before it was spoken.
A leftward and downward change in eye position announced that the next number would be smaller than the last, the scientists said. Correspondingly, upward and rightward forecast a larger number than the last. The degree of eye movement reflected the size of the numerical shift.
The paper was published March 23 online in the research journal Current Biology.
“When we think of numbers we automatically code them in space, with smaller number falling to the left and larger numbers to the right. That is, we think of them along a left-to-right oriented mental number line—often without even noticing this number-space association ourselves,” said researcher Tobias Loetscher of the university, an author of the study.
“This study shows that shifts along the mental number line are accompanied by systematic eye movements. We suggest that when we navigate through mental representations—as for example numbers—we re-use brain processes that primarily evolved for interacting and navigating in the outside world.”
“This study will hopefully provide a template to investigate how the human mind works via a connection with the space and world around us,” added co-author Michael Nicholls.
The study involved asking twelve right-handed men to name 40 numbers between one and 30 in a sequence as random as possible, paced by a metronome. For each number, the researchers measured the average eye position during the half-second before each numbers was declared.