Rationale
Recent animal research has shown that, aside from its primary and secondary reinforcing effects, nicotine may enhance reinforcement
from stimuli unrelated to nicotine intake. Little human research has directly examined this potentially important influence
of nicotine.
Objectives
We report two virtually identical studies examining the influence of nicotine, via nasal spray (study 1) and cigarettes (study
2), on the reinforcing effects of rewards unrelated to nicotine intake.
Materials and methods
Both studies involved young adults with some past smoking exposure but no history of nicotine dependence. Reinforcement was
assessed by responses on a simple operant computer task reinforced by: money, music, the termination of aversive noise, or
no reward (control). Participants responded for rewards on three separate sessions, involving intermittent dosing of 0, 5,
or 10 μg/kg nicotine via nasal spray (study 1) or the smoking of 0.05 or 0.6 mg nicotine cigarettes or no smoking (study 2).
Results
Results showed no effects of nicotine, by nasal spray or cigarette smoking, on reinforced responses, although nicotine increased
some subjective responses (e.g. head rush/buzzed, liking). Nicotine via smoking also did not influence affect or hedonic ratings
of slides varying in mood valence in an exploratory trial in study 2.
Conclusions
These results do not support the notion that nicotine per se enhances the reinforcing value of other reinforcers in humans.
Any reinforcement enhancing effects of nicotine in humans may be specific to dependent smokers or may be relatively narrow
and dependent upon procedural conditions different from those in the current studies.
Keywords Nicotine - Reinforcement - Reinforcement enhancement - Reward - Smoking