EXTENSIVE clinical observations of children usually diagnosed as autistic, schizophrenic, symbiotic-psychotic, and with "atypical ego development" indicate that they manifest similar features and can be best understood as suffering from variants of a single disease1. Their symptoms can be grouped into five subclusters which make their similarities clear: (1) disturbances of perception, (2) disturbances of motor behaviors, (3) disturbances in the ability to relate to others, (4) absent or pathologic language development, and (5) disturbances of developmental rate. The disturbances of perception appear to be fundamental to the other aspects of the disease. The total symptom complex suggests that there is an underlying neuropathology2 which leads to periodic overloading and underloading of the central nervous system. These alternating states of excessive facilitation and inhibition vary the child's awareness and response to the same stimuli and causes what we have termed perceptual inconstancy.
Ritvo ER, Ornitz EM, La Franchi S. Frequency of Repetitive Behaviors in Early Infantile Autism and Its Variants. Arch Gen Psychiatry. 1968;19(3):341-347. doi:10.1001/archpsyc.1968.01740090085008