Leonardo

On the Effects of Flashing White and Coloured Light on HumansAuthor(s): Albert GarrettSource: Leonardo, Vol. 9, No. 3 (Summer, 1976), pp. 213-214Published by: The MIT PressStable URL: http://www.jstor.org/stable/1573557 .

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Leonardo, Vol. 9, pp. 213-214. Pergamon Press 1976. Printed in Great Britain

ON THE EFFECTS OF FLASHING WHITE AND COLOURED LIGHT ON HUMANS

Albert Garrett*

The level of discussion on flashing light in Leonardo, arising from Robert B. Baldwin's article [1], by Richard I. Land [2] and Baldwin [3] impressed me. In Baldwin's earlier article in Leonardo [4], he cautioned artists of the danger of flash rates of between 8 and 12 per second for epileptics or potential epileptics, but he did not draw attention to research that was carried out on this subject by W. Grey Walter and his co- workers at the Burden Neurological Institute, Bristol, England [5, 6]. Since 1946 the medical implication of flashing light has been understood. I consider the terms 'strobing', 'stroboscopic', 'intermittent' and 'flickering' light as synonymous with 'flashing' light.

Although I do not apply flashing light in kinetic art objects, I do teach on the properties and uses of natural and artificial light to architecture students at the Polytechnic of North London and I advise the Federation of British Artists on exhibitions of kinetic electric light art and public safety.

In Ref. 7 I reported on a medical survey (edited by Alice R. Kendall) that I made in connection with two occurrences of severe physical reactions to flashing light. The first occurred in a discotheque in 1971 at Bournemouth, England, were a number in a party of students collapsed and had to be taken to hospital. The second took place during a lecture on light at a London art school given by A. W. S. Tarrant of Surrey University, when he demonstrated light sources operating at about seven flashes per second.

Tarrant described what happened at his lecture as follows [8]: 'About five seconds after starting the strobe I realized that the effect was far worse than I had ever previously, and that I must switch it off. However, I was now so disturbed that I feared that I was not going to be able to grope my way back to the switch before I blacked out. I just made it, but it was quite a few seconds before I gathered my wits sufficiently to put the room lights on. When I did so I saw that my students were in a far worse state than I. Some had sprawled out of their chairs, and on enquiry it was found that several had blacked out briefly. All felt that they would have blacked out had I not switched off when I did'. He found the occurrence frightening and added: 'I am quite sure that the exclusion of all "steady" light made the effect of the flashing light much more severe'.

W. G. Walter in his contribution to my survey [7] said: 'I can assure you that this is a real phenomenon; I discovered it in relation to the frequency analysis of epileptic records, and also made a survey of normal

* Artist and Teacher living at 10 Sunningdale Ave., Eastcote, Ruislip, Middx. HA4 9SR, England. (Received 19 Nov. 1975.)

subjects. In all, the feelings were "weird"-displace- ment in space and sometimes in time. About 25 % of the normals showed epileptic type waves in their electro-encephalograms in their first trials, but they "habituated"; epileptics increase their pathological response.-The "magic" frequency is usually between 14 and 18 flashes per second, but other rates can be effective, particularly with frequency modulation'.

Baldwin [4] reported that of some 2,000 people who has seen his flashing light kinetic picture about 10 reported what he calls 'strobe sickness' at certain flash rates-they felt dizzy and nauseous, but as soon as the lights were turned off they recovered. He operated the lights at rates between 1 and 25 flashes per second.

R. A. Weale of the Department of Visual Science, Institute of Ophthalmology, University of London, says in the survey [9]: 'It is clear that the mere risk of an episode must override all considerations of commerce and search after pleasure, and rules out the use of strobing lights at the above frequencies in public places'. 'It is conceivable that a subtle modification of the mode of strobing may remove its sting while yet preserve the pleasure it gives to some people.'

William Gooddy, a neurologist at University College Hospital, London, in connection with the survey [10] said: 'As a physician concerned with brain function and disease I may say that it has been known amongst neurologists for many years that flickering light may produce abnormal mental states; and in rare instances typical epileptic fits'.

'I have seen just such a case today; and I have come across at least six others in the past few years. Two well known causes of epilepsy in relation to flicker are television sets when not properly adjusted and low sunlight through trees, affecting drivers'.

Flashing light equipment is being manufactured for war and riot-control purposes, which one can take to mean that the equipment is effective. Evidently, some of the higher flashing rates have no ill effects. The early cinema used 16 to 18 pictures per second and the present day frequency is 25 per second and sometimes even higher. But the reports of headaches experienced by typists when working long hours under fluorescent lamps that have 100 flickers per second need to be taken into account seriously.

The comments above were concerned with 'white' light, but kinetic artists use also flashing 'coloured' light sources.

In my summing-up report on the survey [11] I said: 'Kinetic designers have moved into the field of coloured light applied to an enclosed architectural space and here the human being faces the effects of time and of colour saturation and/or starvation and probable

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Albert Garrett

induction effects, where hues reported as seen differ from the physical stimulus-before the necessary research is available'. Rooms in buildings used for kinetic colour projections are generally spectrally deficient environments for humans, who have evolved in an environment where light is received from the Sun. When one introduces 'coloured' flashing lights in rooms with spectrally deficient illumination, one might expect that the human visual system will produce unusual and, perhaps, harmful reactions.

There is an interesting account in the 20 Jan. 1974 issue of the London newspaper Sunday People entitled 'Guests Turned into Flying Zombies at the Village Hop'. It tells about a party at which a coloured 'strobe' disk was used to provide a 'special' environ- ment. When the flashing light was turned on, the guests began to manifest strange hallucinatory reac- tions. The police were called, but no evidence of the use of hallucinogens was found. One might conclude that the reactions were caused by the flashing 'coloured' light.

More knowledge of the reactions of humans to flashing 'white' and 'coloured' light is needed, especially for kinetic artists who make use of such light. I under- stand that in Britain, if damages were claimed for harm done to a viewer of kinetic art of this kind, the legal charge would be that the owner of the building permitted persons to enter dangerous premises.

I would welcome information from anyone who has encountered harmful human reactions to flashing light, in order to help those who establish controls on the use of flashing light in public places.

References

1. R. B. Baldwin, Kinetic Art: On the Use of Sub- liminal Stimulation of Visual Perception, Leonardo 7, 1 (1974).

2. R. I. Land, On the Physical Behavior of Flashing Incandescent Light Sources, Leonardo 8, 232 (1975).

3. R. Baldwin, Letters, Leonardo 8, 359 (1975). 4. R. Baldwin, Kinetic Art: On Producing Illusions by

Photo-Stimulation of Alpha Brain Waves with Flashing Lights, Leonardo 5, 147 (1972). Also in F. J. Malina, ed., Kinetic Art: Theory and Practice (New York: Dover, 1974) p. 119.

5. W. G. Walter, V. J. Dovey and H. W. Shipton, Analysis of the Electrical Response of the Human Cortex to Photic Stimulation, Nature 158, 540 (19 Oct. 1946).

6. W. G. Walter and H. W. Shipton, The Effect of Synchronizing Light and Sound Stimuli with Various Components of the Electro-Encephalogram, J. Physiology 108, 15 (1949).

7. A. Garrett, Kinetic Art, Stroboscopic Light and U.V. Radiation, Fed. Brit. Artists Quarterly 1, 17 (Summer 1972).

8. A. W. S. Tarrant, Strobing Light and U.V. Lamps, Fed. Brit. Artists Quarterly 1, 18 (Summer 1972).

9. R. A. Weale, U.V. Light and the Human Eye, Fed. Brit. Artists Quarterly 2, 19 (Spring 1973).

10. W. Gooddy, Strobing Light and U.V. Lamps, Fed' Brit. Artists Quarterly 1, 18 (Winter 1972).

11. A. Garrett, Strobing Light Sources and U.V. Radia- tion, Fed. Brit. Artists Quarterly 2, 23 (Autumn 1973).

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