On the Effects of Flashing White and Coloured Light on Humans

Leonardo, Vol. 9, pp. 213-214. Pergamon Press 1976. Printed in Great Britain ON THE EFFECTS OF FLASHING WHITE AND COLOURED LIGHT ON HUMANS The level of discussion on flashing light in Leonardo, arising from Robert B. Baldwin’s article [I], 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 coworkers at the Burden Neurological Institute, Bristol, England [5, 61. 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 offwhen 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”4isplacement in space and sometimes in time. About 2504 of the normals showed epileptic type waves in their electroencephalograms 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...