Concealed information revealed by involuntary eye movements on the fringe of awareness in a mock terror experiment.

Involuntary eye movements during fixation are typically inhibited following stimulus onset (Oculomotor Inhibition, OMI), depending on the stimulus saliency and attention, with an earlier and longer OMI for barely visible familiar faces. However, it is still unclear whether OMI regarding familiarities and perceptual saliencies differ enough to allow a reliable OMI-based concealed information test (CIT). In a "mock terror" experiment with 25 volunteers, 13 made a concealed choice of a "terror-target" (one of eight), associated with 3 probes (face, name, and residence), which they learned watching text and videos, whereas 12 "innocents" pre-learned nothing. All participants then watched ~ 25 min of repeated brief presentations of barely visible (masked) stimuli that included the 8 potential probes, as well as a universally familiar face as a reference, while their eye movements were monitored. We found prolonged and deviant OMI regarding the probes. Incorporated with the individual pattern of responses to the reference, our analysis correctly identified 100% of the terror targets, and was 95% correct in discriminating "terrorists" from "innocents". Our results provide a "proof of concept" for a novel approach to CIT, based on involuntary oculomotor responses to barely visible stimuli, individually tailored, and with high accuracy and theoretical resistance to countermeasures.