Aladjalova (1964) described physiological and behavioural harmonic processes which were considered with Lacey's (1958) and other random process theories. Two experiments were carried out: the first obtained evidence for harmonic characteristics in autonomie processes and the second showed that these characteristics were independent of those obtained on a signal detection task. These results were discussed with evidence for the existence of harmonic characteristics in perceptual‐motor tasks (Tainsh, 1972) in terms of slow and fast psychological control systems.