Distinguishing withdrawal relief from absolute facilitation: commentary on Bell et al

A recent article in this journal by Bell and colleagues (Bell SL, Taylor RC, Singleton EG, Henningfield JE, Heishman SJ, Nicotine & Tobacco Research 1:45-52, 1999) studied the effects of smoking on cognitive performance using an overnight smoking abstention design. They interpreted their results for a two-letter search task (poorer performance following abstention that was improved by smoking) as indicating 'nicotine withdrawal-induced cognitive impairment' (p. 50). However, in this commentary, we point out that overnight-abstention experimental designs cannot distinguish withdrawal relief from absolute facilitation of performance (or a combination of the two). We suggest two approaches to resolving the issue of the nature of smoking/nicotine's effects on human cognitive performance.