Mitsuru Kokubun

Factors Affecting Age of Walking by Children with Mental Retardation

The relationship between age of walking and two factors of severity of intellectual disability and clinical types (autism, Down syndrome, epilepsy, and “residual”) in children with mental retardation was investigated. Subjects were 118 children whose disabilities ranged from severe to mild. Measures by clinical type were significant, and the differences of any two clinical types except between children with epilepsy and the “residual” group were significant, but severity of intellectual disability was not significant. Most children with autism (27 subjects, 93%) walked by the normal time limit of 18 months. Only 3 children (11%) with Down syndrome began to walk within that limit, and 9 of them (33%) walked after 2 years of age. In the “residual” group (including children with epilepsy), 37 children (60%) walked within the normal limit but 15 (25%) only after 2 years of age.

Developmental Trends in Pursuit Eye Movements among Preschool Children

The purpose of this study was to investigate the developmental differences in pursuit eye movements among preschool children. The subjects were 28 children aged 3 to 6 years old and 5 adults aged 22 to 37 years. The target was moved sinusoidally on the horizontal plane at 0.3-, 0.5-, and 0.7-Hz stimulus frequency. The power ratio which represented the smoothness of eye movements and the phase difference between eye movements and target movement was calculated. The power ratio decreased with increased stimulus frequency for all subjects, indicating that eye movements became less smooth. At all stimulus frequencies, the power ratio was higher for adults than for children. Among the three age groups of children, there was no statistically significant difference on this parameter. The phase shifted from a small amount of lead for no lag to the lag with faster stimulus frequency in adults, but the gap was not statistically significant. For children, there was a statistically significant difference across age groups on change in the phase difference. These findings may suggest that the developmental differences in pursuit eye movements of children across ages 3 to 6 years were clear in what related to the phase difference.

Postural Sway in Normal and Mentally Retarded Persons

The purpose of this study was: (1) to examine the magnitude of postural sway in persons with mental retardation (PMR) according to clinical types of retardation in comparison with non-handicapped persons, and (2) to investigate the relation between magnitude of sway (MS) and body balance exercises (beam walking and one-foot balance) according to clinical types. The subjects were 134 non-handicapped persons and 45 PMR. The results were as follows: (1) The average MS of autistic persons and other PMR was about the same as that of non-handicapped children aged 4 or 5 years. Among other PMR, however, the MS distribution was relatively large. On the other hand, MS in persons with Down syndrome was generally small, and was similar to that of nonhandicapped children aged 6 years; this small MS appeared to be characteristic of the syndrome. (2) With regard to MS and body balance exercise performance, all subjects in the small magnitude group belonged to the high-performance group except for the persons with Down syndrome.

Development of Psychological Aspect in Pursuit Eye Movements among Preschoolers

This paper is a reply Co LeGare (1996) who affirmed all characteristics in the development of pursuit eye movements in preschoolers should be ascribed only to the immaturity of the visual systems structure.