Abstract

Human observers are extremely accurate at determining the gaze direction of another person.The investigations reported here aimed to clarify discrepant data on whether gaze direction is easier to detect in the horizontal (Cline, 1967 American Journal of Psychology 80 41 ^ 50) or
vertical plane (Anstis et al, 1969 American Journal of Psychology 82 474 ^ 489) and in monocular or binocular conditions (Symons et al, 2004 Infant Behavior and Development 21 531 ^ 536). Observers viewed photographs of a looker and it was found that vertical eye movements were
easier to determine than horizontal eye movements thresholds 0.467 and 1.064 min of arc, respectively); in addition there was no difference between binocular and monocular thresholds (0.747 and 0.784 min of arc, respectively). These findings support Anstis et al's (1969) claim that vertical eye movements are easier to determine, furthermore they challenge Symons et al (2004) because presentation of both eyes is not needed to accurately determine gaze direction.