Temporal rhythms and cerebral rhythms.

A model for the internal clock is briefly described. It includes a temporal pacemaker whose rate determines time judgments, and whose frequency is affected by arousal specific to it. Three hypotheses relating time judgments and the alpha rhythm are considered: (a) They may be wholly independent, each reflecting the specific arousal of the mechanism determining it. (b) The alpha rhythm may be an index of a state of general arousal which also acts on the temporal pacemaker. Because of this common influence, the alpha frequency, and the proportion of alpha in the electroencephalogram, may be correlated with the speed of the temporal pacemaker. (c) The same pacemaker may be common to the internal clock and an alpha rhythm generator. Concurrent observations on alpha frequency, alpha prevalence, and temporal productions show that there are no simple relations between these measures such as might support the general arousal or common pacemaker hypotheses. However, relations are found between the variables. More or less regular oscillations occur in their values, some of which are common to two or more of the variables studied. These phenomena are further investigated and described.