The accuracy of eye-gaze judgment: a signal detection approach.

Two studies are reported which tested the hypothesis that eye-gaze discriminability declines with increased interpersonal distance and that this decline produces an overestimation bias. Signal detection theory was used to provide separate indices of discriminability and bias. Discriminability declined with both increased distance and, in one study, with decreased lighting. The tendency of the subject to guess that gaze was occurring when it was not mirrored the changes in discriminability, supporting the hypothesis.