Electro-Oculography: Drawing with the Eye

Leonurdo, Vol. 2, pp. 399401. Pergarnon Press 1969. Printed in Great Britain Pen recorder I NOTES-NOT€S Inthissectionof Leonardo textsnot exceedingabout 1200wordswillbepublished. Notes will not be accompaniedby abstracts and, generally, only three black and white illustrations will be allowed. Accepted Notes will be published more quickly than longer texts. Des textes ne ddpassent pas 1200 mots seront publie's dans cette rubrique de Leonardo. Ces Notes paraitront sans re'surnds. Elles pourront etre accompagndes , de manisre gdndrale, de trois illustrationsen noir et blanc. Les Notes acceptees seront publidesplus rapidment que les textes plus longs. ELECTRO=OCU LOGRAPHY: DRAWING WITH THE EYE Richard 6. Coss" Drawing with the hand is coordinated through the visual impressions transmitted to the eyes and interpreted by the brain. During the making of a drawing, three major events form a closed loop. First of all, the eyes perceive the orientation of the hand in relation to the paper's surface. The second event is the brain's decision to move the hand in a particular manner. The third event comprises the actual hand movement, which marks the paper. The cycle of events then instantly repeats itself, leading either to correction or continuation of the drawing. Suppose,conceptually, that thehand wasremoved from the loop of events and the artist could draw by merely looking at the paper where he wanted to make a mark. There would then be an immediate feedback and interplay between the eyes and the brain that would eliminate some of the limitations of the usual manual way of drawing. How could drawing with the eyes be achieved? For many years, equipment has been in use that could record eye movements. Up till now, this equipment has not been sophisticated enough to convert eye movement directly into the mechanical movement necessary for drawing. One technique that shows promise is the development of the corneo-retinal potential method for detecting eye movements [l]. Within the eyeball there are electromotive solutions (aqueous and vitreous humor) separated American industrialdesigner, Cornpagniede 1'Esthttique Industrielle-Raymond Loewy, 39 Av. d'Itna, 75-Paris 16, France.(Received 11 June 1969.) by two cavities that comprise the front (cornea) and back (fundus) portion of the eye. Each solution is polarized by a small electrical charge. The front section of the eye is positively charged and the back section is negatively charged. If two electrodes are placed on the skin on either side of the eye, the difference of electrical potential between the front and back of the eye can be measured because the eye acts like a small battery. When the eye rotates in its orbit, the positively charged cornea generates a positive charge in the nearest electrode while the negatively charged fundus produces a negative charge in the opposite electrode. The difference of electrical potential between the electrodes can be amplified and recorded on a pen-strip chart to provide an indication of the angular rotation of the eye. This technique for measuring eye movement is called electro-oculography (EOG). When four electrodes are equally spaced around the eye and coupled with a two-dimensional X-Y recorder, it is possible to measure the movements of an eye in both the vertical and horizontal plane (cf. Fig. 1). The Garrett AiResearch Company of 399 Richard G. Coss Fig. 2. Layout of seated subject and screen (cf. Ref. 2). Los Angeles, California, recently developed a visually scanned by the subject and traced by the refined version of the EOG for the American space X-Y recorder at the same time. research program using four electrodes to measure I had the opportunity, several years ago, to eye movements during visual search behaviour [2]. experimentwith the EOG as a subjectfor a demonstration . After visually scanning and fixating various patterns placed on a screen in front of me, I was able to create one drawing. I imagined a fast-back sportscar and projected this mental image on the screen (cf. Fig. %a)). I then requested the 1 v Fig . 3. Tracing of eye movements as subject visually scanned enlarged signature. Eye movement recording by the EOG system is not difficult to employ and simple adjustments of amplifier gain for the vertical and horizontal...