The visual perception of fine detail

Abstract Many books have been written on colour vision; not so many on the appreciation of form and shape. Few have dealt exclusively with the perception of fine detail. All the experiments described in this paper have one object in view, namely, to elucidate some of the mechanisms, both nervous and otherwise, by which the image formed on the retina is clarified and improved before it reaches the higher centres of the brain. Brief reference must now be made to some of the difficulties encountered during the performance of the experiments described in this paper. These were of three kinds: apparatus, research rooms, assistants, When in 1939 the pre-medical branch of St Bartholomew’s Hospital Medical College was evacuated to Cam bridge, very little room space could be allocated for research purposes. At the same time the assistants and laboratory attendants were almost wholly occupied in class preparation and had no time to spare to help with research. In 1942 the Physiology block of the London buildings was gutted by fire and all the author’s research equipment, books, journals and reprints were destroyed. The apparatus thus destroyed was almost impossible to replace at that time. The position, so far as apparatus is concerned, has changed recently for the better, as a special instrument has now been constructed, which has shown itself to be suitable for the tasks for which it was designed. This is described in Part X. I would like to thank my colleagues; those in the Cambridge laboratories; those evacuated with us from London; and particularly those who belong to Bart’s. Without their co-operation and encouragement the experiments described in these pages could never have been done at all.