General lighting with a uniform level of illumination over the working plane was introduced and adopted in the inter-war period. Before this, local lighting over tho work itaelf had been customary. It was found, however, that general lighting was not always satisfactory for work which demanded high degrees of visual skill and attention, and in many cases a return to local lighting, together with some general lighting, was favoured. It is generally accepted that the attention is held by objects which contrast strongly with their environment, cithor by their brightness, colour, texture or form. Equally the attention can bo distracted by a bright or highly coloured object in tho field of view a little away from tho object of regard. Experiments have been made in ' human phototropism ', employing apparatus which enabled a simultaneous cine-photographic record to be made of the visual scene togother with the eye movements of an unsuspocting observer viewing the Bcene. A count of the number and duration of these eye movements revealed that sharp, intensely bright points of light distracted the attention in a series of jerky oyo movoments, whereas loss bright but larger areas causedmore eye movements of longer duration. Different behaviour patterns of different observers were noticed, two rather distinct groups being recognized which bear many striking similarities to the ‘ postural-cluo’ and the ‘visual-clue ’ personality groups recognized by Witkin (1950). Some applications of tho results to tho lighting of work-places are suggested. Tho results argue in favour of preferential lighting of tho work, possibly by local lighting.
Read full abstract