Enhancement of continuous performance task reaction time by smoking in non-deprived smokers.

In a test of the withdrawal-deficit hypothesis of the cognitive effects of cigarette smoking, non-deprived smokers participated in two sessions held on consecutive days. In both sessions, subjects performed two 20-min continuous performance tasks (CPTs). The CPT was a relatively "easy" version designed to require minimal practice (digit 0 target response; digits 1-9 nontarget response; 19% of stimuli targets). In one session, subjects smoked a cigarette prior to each CPT; in the other session they did not smoke (session order counterbalanced). Reaction time (RT) was significantly faster in the smoking session than in the non-smoking session with no difference in number of incorrect responses, a finding incompatible with the withdrawal-deficit hypothesis. Further, light inhalers (as assessed by pre-smoking to post-task increase in expired air carbon monoxide) appeared to process nontarget stimuli faster than deep inhalers, especially in the no smoking session. The results also indicated that, at least during the first CPT of each session, the performance of females in the no smoking session was poorer than in the smoking session and poorer than males regardless of session. In the latter part of the first CPT, the performance of males in the smoking session was better than their performance in the no smoking session. No clear pattern emerged for the second CPT.