Ocular motility as an indicator of verbal and visuospatial processing

Three experiments were conducted to study ocular motility as a function of cognitive task. Horizontal eye movements were recorded electrically as normal adults attempted to answer auditorily presented questions that were either verbal-conceptual or visuospatial in nature. In each of the three experiments, verbal-conceptual questions elicited significantly more eye movements than did visuospatial questions. Direction of initial movement was a less reliable indicator of question category. Experiment 1 showed that the difference in eye movement rate associated with question category persisted throughout the period of deliberation; in Experiment 2, consistent differences in ocular motility were obtained with diverseverbal-conceptual and visuospatial questions; Experiment 3 showed that the effect is found even when an oral answer is not required. These findings cannot be attributed to differences in task difficulty or response factors. A low eye movement rate may facilitate visual thinking by reducing interference from the environment, or it may reflect bilateral activation of the cerebral hemispheres.