Scanning the seen: vision and the origins of eye movement research

Investigations of eye movements pose several paradoxes. Interest in recording eye movements has been informed by studies of vision. The importance of scanning a scene was recognized theoretically before it was examined experimentally. The contrast between the restricted range of distinct vision and the experience of a uniform and clear visual field focused attention on rapid eye movements. However, they were reported initially in the context of visual vertigo following body rotation; characteristics of the slow and fast phases of nystagmus were recorded by comparing the apparent motion of an afterimage with that of a real image. Afterimages were next employed to record torsion when the eye was in tertiary positions. Saccadic eye movements when reading or viewing pictures were measured with a variety of devices from the late 19th century. Vision was generally restricted to the short periods of fixation between saccades. The restriction of distinct vision to a small region around the visual axis led to considerations of how a full impression of the visual surroundings could be formed. The chapter presents experimental studies of eye movements with the more detailed examinations of reading that were undertaken at the end of the 19th century and the beginning of the 20th.