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Contents
1. THE BASIC PROBLEM OF ACQUISITION
Of man’s 5 senses vision is claimed to provide some 75% of the total input to the
brain about his environment. This means both that the amount of data being
received through two small optical sensors is truly enormous and that it is
important to know how this information is received and processed. Not
surprisingly a very great deal of research effort has gone into discovering more
about man’s visual system over many, many years. Researchers are hampered,
however, by the fact that the visual receiver - the retina at the back of the
eye -has numerous individual detectors implanted in it which are known to
couple through a very complicated array of neural networks to the cortex.’ It is
hardly practical to probe deep into these networks with living subjects and,
although some work has been carried out on eyes bequeathed to medical
research by deceased persons, there is a severe limit on what can be learnt from
such studies. This has led many scientists to carry out extensive studies on
various forms of lower animals, from which a great deal has been learnt as to
what might be facets of human vision. However, in the author’s opinion care
should always be taken in drawing too close parallels between the established
behavioural characteristics of the visual systems of lower animals and that of
man. It seems highly probable that evolutionary processes will have been largely
responsible for roughly optimising a given animal’s visual system for its
environment. Having said this, it is difficult to justify an assumption that, say, a
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