AN EXPERIMENTAL STUDY OF TACTUAL AND VISUAL DISCRIMINATION IN CHILDREN WITH DOWN'S SYNDROME : THE VARIETY OF DISCRIMINATION RESPONSES EFFECTED BY DIFFERENT KIND OF STIMULUS PRESENTATION

The present paper is to investigate experimentally whether the responses for tactual and visual discrimination of children with Down's Syndrome is effected by different presentations of the stimulus figures. Two experiments were conducted: Experiment I deals with the tactual discrimination and Experiment II deals with visual discrimination. Each experiments was performed by using the same sensory modality. For each of the two experiments, two different conditions of stimulus presentation were set as follows. 1) The condition of successive presentation: the subject observes tactually or visually a stimulus figure with his dominant hand and after that discriminates tactually or visually from among several figures with his dominant hand the same as the stimulus figure. 2) The condition of simultaneous presentation: the subject performs tactually or visually to look at the stimulus figure and to discriminate the same as the stimulus figure from among several figures, at the same time. For tactual discrimination task, six geometrical figures made of plastics were provided as experimental material. The experimental figures are isosceles triangle (in height 7cm, in base 14cm), semicircle (in diameter 12cm), diamond (in long axis 11cm and in short axis 8cm), square (in side 8cm), cross shaped (vertically and horizontally 9cm and in width 3cm), rectangle (7 by 10cm). For visual discrimination task, six figures as stimulus material were given which were drawn with black feltpen on a 25×20cm white card. The number of the subject children were 40 Down's Syndrome, 40 Non-Down's Syndrome and 40 normal children. The subjects of each group were separated into two groups of Experiment I and Experiment II. After that again they were divided into subgroups (one group 10 in unmber) according to the condition of stimulus presentation. Both groups of Down's Syndrome and Non-Down's Syndrome were matched in MA and IQ and the average CA of normal children was equaled to the MA of Down's Syndrome. The performances in children with Down's Syndrome were compared with those made by both Non-Down's Syndrome and normal children. The subjects were run individually. The test was performed without time limit. The results were as follows. 1) The children with Down's Syndrome were significantly deficient to both Non-Down's Syndrome and normal children in making the tactual discrimination tash by successive and simultaneous presentation. However, the effect of discrimination responses by different types of stimulus presentation was not distinctly marked in children with Down's Syndrome. 2) The children with Down's Syndrome were as well as in Non-Down's Syndrome and normal children on visual discrimination task of simultaneous presentation. But, the children with Down's Syndrome were inferior in performances of successive presentation to that of other groups. From the results mentioned above, it will be suggested that children with Down's Syndrome were influenced by the experimental situation where the figures were presented of the stimulus presentation.