Motor potentials and motor performance associated with introverted and extraverted smokers.

Motor potentials associated with a motor task and with the initiation of the smoking act were recorded from two groups of 5 introverted and 5 extraverted smokers during sham and real smoking sessions on two separate occasions. The aim was to test hypotheses derived by O'Connor from the motor model of smoking: firstly, that change in background motor set would alter the smoker's smoking pattern, and secondly, that smoking would principally affect extraverts' general motor preparation (as measured by motor potentials preceding a tapping task), whilst improving introverts' selective inhibition (as measured by performance on a tracking task requiring skillful co-ordination). Smoking did increase the motor readiness potential preceding tapping in extraverts. Smoking decreased involuntary rest pauses of introverts and their error on the tracking task. There were, however, no differences in puff parameters across motor conditions. But larger motor potentials preceding the smoking act in introverts indicated a greater involvement of introverts in the smoking act itself. The results offer limited support to the proposal of the motor model that motor demand regulates both the motivation to smoke and the effects of smoking.