[Laterality in institutionalized patients with moderate, severe and very severe mental retardation and stereotyped behavior].

A total of 54 moderately (n = 13), more severely (n = 27) and severely (n = 14) mentally retarded persons living in institutions were dealt with in this paper. Qualities of their stereotyped actions were analysed and compared in respect to the used lateralization according to Cordić-Bojanin's modified scale and to Berg's scale for used lateralization. Results obtained pointed to the differences among stereotypes themselves in respect to the influence of social environment and the degree of retardation. Therefore, twisting of the body was regarded as the "mildest" form of retardation and passivity, while the motions of hands only were associated with the most severe ones. Used lateralization in the form of dextrality occurred in 62.96%, in the ambidextrality in 14.8% while sinistrality accounted for 22.2%. Right-handed persons most frequently showed stereotyped behaviour which was manifested by the forward-backward motion of the body, while left-handed persons showed stereotypes connected with hands. It was believed that the tonus which represented the termination of the voluntary action and the basis of the development of lateralization would be regarded as the connection between lateralization and stereotypes.