Effects of smoking on free recall and organization.

Habitual smokers smoked either nicotine-free cigarettes or cigarettes containing a known amount of nicotine and then engaged in a free-recall task. Nicotine subjects recalled significantly fewer words on a 75-item list during three successive trials of immediate recall than did nicotine-free subjects. Contrary to expectations, the superiority of the nonnicotine group persisted over two days. The two groups displayed comparable organizational activity (indexed by category clustering).