Previous work in this and another laboratory has shown that nicotine tablets improve the performance of a rapid information processing task and reduce the Stroop effect, whereas scopolamine has the opposite effects. The purpose of this study was to extend these previous findings by determining whether, when administered together, these two drugs have mutually antagonistic effects on task performance. Two experiments are reported, both using within-subjects double-blind Latin Square designs. In the first, six subjects received single and combined doses of scopolamine 1.2 mg and nicotine 1.5 mg, and there was some evidence that the two drugs had mutually antagonistic effects on the rapid information processing task. In the second experiment 12 subjects received the same doses, but rapid information processing testing was carried out over a longer time period and Stroop testing was introduced at the end of the 2.5 h session. Nicotine was found to counteract the depression of performance produced by scopolamine on both the rapid information task and the Stroop test. These results provide further support for the theory that central cholinergic pathways play a major role in human information processing.

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A new version of the Rapid Visual Information Processing (RVIP) task has been developed in this laboratory to examine the effects of each puff from a cigarette upon continuous performance. Two cigarettes were tested and compared with a not-smoking and a sham-smoking control. The results show improvements resulting from just two puffs both in terms of correct detections and reaction times. Both measures of performance were maintained at a higher level during and after smoking, compared with not-smoking and sham-smoking.

The models achieved a consistent, high level of accuracy in predicting treatment responses, which was markedly superior to that of genotypic sensitivity scores. The models are being used to power an experimental system now available via the Internet.