Discrimination of size, form and order in mongol and other mentally handicapped children

136 mongol, 129 non-mongol subnormal and 152 normal children were tested in a series of experiments to determine visual discrimination and perceptual skills in size, form and order. An attempt was made to demonstrate possible differences in strategies and behaviour in the groups, particularly in the mongol group. It was shown that, in spite of contrary impressions arising from results of normal standardised tests, in these three groups matched on M.A., there was no significant difference in performance when extraneous developmental factors were eliminated. The literature relating to this is discussed. There was further support for the existing experimental evidence that poor short-term memory for visual stimuli in terms of size, form and order is a characteristic weakness of subnormal groups. No relationship was found between M.A. and visual perceptual tasks in any group; supporting the theory that perceptual skills develop independently. A peculiar phenomenon was discovered in the mongol group significant enough to warrant further investigation, viz. a distinctive form of perseveration and a related and clearly marked tendency to order reversal. Suggestions are made and possible reasons presented for this, but, at this stage, without experimental backing.