Weisman studies the problem of tics in adult patients and reports several cases of psychoneurosis in which tic was a presenting symptom. He defines and describes this symptom, giving as the three characteristic features of tic: 1, its occurrence in functionally related groups of muscles; 2, its association with irresistible tension; 3, its partial control by the will. He outlines the various classifications of tics which have been employed, 'depending on the specific bias of the investigator'. He differentiates between primary and secondary tics on a psychological basis. Primary tics represent a discharge of aggressive or erotic feelings in the presence of an impaired ego, are most common in children, and do not constitute a psychoneurotic symptom. Secondary tics, which are the type usually seen by clinicians, represent fusions of impulse and defense.