Effects of nicotine gum on repeated administration of the Stroop test.

Using a double-blind procedure, 24 non-smoking subjects chewed either 2 mg nicorette gum or a placebo for 20 min, before completing a Stroop test on three occasions. Colour-word reading and simple colour naming times were consistent across repeats, and were unaffected by nicotine. However, the time taken to name the colour of incongruous colour word stimuli declined across trials. This increase in speed across repeats was significantly greater in those subjects who had received nicotine. These data are consistent with previous reports of a decreased Stroop effect following nicotine administration, but are not compatible with a simple model which assumes that nicotine alters the way in which information is filtered by selective attentional mechanisms. The present results can be explained by postulating that nicotine influences either the rate at which colour naming become more automatic, or changes the way in which resources are allocated to non-automatic processes.