The article above from PennState University is one of the first ones on the topic to ever be published, dating back to 1994. There are 5 important measures in this study: the reaction Times (RT), inspection Times (IT), decision time (DT), movement time (MT) and string length. An excellent drug would be able to reduce all the 4 measured times, and would also increase the string length as longer string length as associated to people with higher IQ. Nicotine hits the home run on all 4 reaction times by reducing them, and also increase the string length. Here is the conclusion of the article, you read the rest here. Conclusion:
Three repeated measures ANOVAs were calculated to test the relationship between mean string length under no-smoking and smoking conditions for central (Fz, Cz and Pz), left hemisphere (01, T5, P3, C3, T3-P3, F3, FP1 and F7) and right hemisphere (02, T6, P4, C4, T4-P4, F4, FP2 and F8) electrode sites . ANOVAs indicated that string lengths, as predicted, were significantly longer in the smoking condition than in the no-smoking condition for central (F1 ,9 = 4.3, P< 0.05) and right (F1,19 = 2.7, P< 0.05) hemisphere electrode sites, and approached significance for left hemisphere electrode sites (Ft,,y = 2 .3, P = 0.07). The relationship between string length and smoking conditions at the three groups of electrode sites is represented in Fig . 1(a), (b) and (c). The results support the hypothesis that nicotine (possibly via its effect on cholinergic pathways), enhances processing of elementary stimuli. As discussed earlier, a significant relationship between string length and IQ has been reported in many studies, with increased string lengths being associated with higher psychometric intelligence (e.g. Blinkhorn & Hendrickson, 1982 ; Haier, Robinson, Braden & Williams, 1983; Hendrickson, 1982b ; Stough, Nettelbeck & Cooper, 1990 ; Widaman, Carlson, Saetermore & Galbraith, 1993). Although the physiological mechanism involved in this relationship is not known at this stage, Hendrickson and Hendrickson (1980) have postulated that increased string lengths reflect more accurate information processing . Interestingly, such cognitive mechanisms as information processing and memory have been associated with central cholinergic pathways in clinical studies using patients with dementia (Broks, Preston, Traub, Poppleton, Ward & Stahl, 1988;Kopelman, 1987) The results of the present experiment are consistent with the hypothesis that nicotine enhances general cognitive ability. This result, if replicated, is important because it may lead to pharmacological enhancements of performance on tasks regarded as reflecting intelligence.