The Role of Movement Patterns in Development—I. Rhythms of Movement

Pleasure and unpleasure, therefore, cannot be referred to an increase or decrease of a quantity (which we describe as 'tension due to stimulus'), although they obviously have a great deal to do with that factor. It appears that they depend, not on this quantitative factor, but on some characteristic of it which we can only describe as a qualitative one. If we were able to say what this qualitative characteristic is, we should be much further advanced in psychology. Perhaps it is the rhythm, the temporal sequence of changes, rises and falls in the quantity of the stimulus. We do not know (21, p. 160).

The problem of excitation, tension, and discharge occurs often in Freud's writings (for instance, [18], [19], [20], [22]). Many of his theorizations about instinctual drives and instinctual energy are based not only on neurophysiological models but on direct observations of movement as well. Breuer and Freud's concept of 'tonic intracerebral excitation', operative in the waking state, seems to be derived from the clinically observable tonus of muscles at rest (18). The closely allied concept of bound and free energy, which pervades Freud's later theories, may well have been influenced by observations of tonic and clonic movements familiar to neurologists. Observations of muscular tensions and relaxations during certain affective and ideational states may have been a further source of Freud's theory of energy.