Anthropometric asymmetry in normal and mentally retarded males

Anthropometric asymmetry was considered in a sample of 202 normal and about 200 mentally retarded males. In addition to height, 11 bilateral measurements of bone, soft tissue and strength were taken. Differences between bilateral measurements were analysed in terms of absolute and signed differences, and in terms of the differences corrected for height. Mentally retarded individuals show greater anthropometric asymmetry than normal individuals in both absolute measurements and those corrected for height. The distributions of the differences, both absolute and signed, are also broader in the retarded, and variances of the left-right differences are greater than variances associated with measurement. Left-right differences between the normal and retarded males occur primarily in the upper extremity; in contrast, side differences in the lower extremity are not great. Within the mentally retarded sample, there are no significant left-right differences among different I.Q. groups. However, there are significant differences among aetiological categories, and those with neurological impairment are more structurally asymmetrical.