Discriminability of nicotine in tobacco smoke: implications for titration.

Cigarette smokers were presented with puffs from either high (2.5 mg), medium (1.5 mg) or low (.5 mg) nicotine cigarettes in order to determine their ability to discriminate nicotine delivery in tobacco smoke. Puffs were presented in random order during each of two conditions and tar content was controlled by using research cigarettes and a smoke mixing device that varied only nicotine. The first condition allowed olfactory stimuli to be used in discrimination, while the second condition blocked olfaction by occluding subjects' nostrils. In both conditions, subjects discriminated between the nicotine content of different puffs, with higher nicotine puffs rated as significantly stronger (by roughly 50%). Subjective desirability ratings did not vary with nicotine delivery. The implications of the magnitude of change in subjects' ratings for theories of nicotine titration are discussed.