Visual discrimination of simple geometrical patterns: II. Atypical responses in a subject suffering difficulties with...

We have applied the experimental methods described by Ike et al. (Spatial Vision, 1987, 2, 13-29) in the study of pattern discrimination by subjects who, during childhood, experienced severe difficulties with reading and spelling. Of the six subjects studied, one still suffers from such difficulties and we show that she performs atypically in certain of the discrimination tasks. In particular, her discrimination responses for elements such as delta are markedly different from those of all other subjects. We interpret these abnormal responses on the basis of the discrimination mechanisms for line orientation and rotation of the elements which were discussed by Ike et al. (1987).