Predictable eye-head coordination during driving

Abstract

LARGE changes in the direction of gaze are made with a combina-tion of fast saccadic eye movements and rather slower head move-ments. Since the first study on freely moving subjects¹, most authors have agreed that the head movement component of gaze is very variable, with a high ‘volitional’ component². But in some circum-stances head and eye movements can be quite predictable, for example when a subject is asked to shift gaze as quickly as possible³. Under these conditions, laboratory studies have shown that the eye and head motor-systems both receive gaze-change commands, although they execute them in rather different ways^3–6. Here I reconsider the way gaze direction is changed during free movement, but in the performance of a task where the subject is too busy to exert conscious control over head or eye movements. Using a new portable and inexpensive method for recording head and eye movements, I examine the oculomotor behaviour of car drivers, particularly during the large gaze changes made at road junctions. The results show that the pattern of eye and head movements is highly preditable, given only the sequence of gaze targets.