"When a person is lying, their emotional load goes up, which causes changes in pupil diameter and gaze position," said Sanborn. The device also measures how long it takes to read and answer certain questions. Pupil size, gaze position and the length of time it takes to respond to questions reflect that the brain is working harder, which the psychologists determined is a sign of lying.
This device is designed to be used for pre-employment screening, but it is not legal for use by private companies, so the company is working with the U.S. government and with foreign firms. He estimates its accuracy to be around 85 to 87 percent.
But the authors of the new study said their work offers proof that no relationship exists between the direction of eye movements and truthfulness.
"Future research could focus on why the belief has become so widespread," they wrote.