Factors influencing relations between tapping speed and alpha rhythm

Abstract

Discrepancies in reports concerning relations between tapping speed and alpha rhythm prompted an experiment to ascertain the effect of differences in method. Results from 67 normal adults, using a variety of tapping tasks, revealed both method and population sample as critical determinants, as follows: 1. 1. Tapping at natural speed (TNS) was uncorrelated with speed of tapping as fast as possible (TF) except when the first task in the experimental series was TF, in which case TF appeared to act as a “pacesetter” for subsequent TNS, the latter gradually decreasing over a number of trials to its “true” natural speed. 2. 2. Marked differences in size and sign of correlations between tapping speeds and alpha frequency among various subgroups were noted, and evidence was produced to show that these were due to the combined effects of task order and population sample. 3. 3. These effects were proposed as mediated by differences in arousal level: in the case of population sample because of varying degrees of motivation, and in the case of task order because of differences in the arousal function of the various tapping tasks. When both effects increase arousal, correlations between tapping speed and alpha frequency will be positive; when they are in opposition, the correlations will be nil, and when they lessen arousal, they will be negative. 4. 4. These differences in correlation according to group level of arousal were attributed to temperamental traits associated with differences in alpha frequency. 5. 5. Implicit in these conclusions is the proposition that a motor speed factor is basically related to alpha frequency, but that its detection will be dependent on control of method and sampling.