Smoking, string length and intelligence

Over the last decade a number of studies have reported significant relationships between physiological and semi-physiological measures of performance—the string length measure of AEP waveform complexity, inspection time (IT) and reaction time (RT) and psychometric intelligence. At present, the neurophysiological mechanism(s) mediating this relationship are unknown. However, some recent smoking studies have reported that RT and IT performance is significantly enhanced in smoking (nicotine) conditions compared to sham smoking (no nicotine) or no-smoking conditions, which suggests performance on such tasks may be mediated by cholinergic systems. In order to further investigate this relationship, the string length which arguably provides the highest correlation with IQ was measured under smoking and non-smoking conditions. As predicted, string lengths were significantly increased in the smoking condition, suggesting that nicotine may enhance the neurophysiological processes underlying general cognitive ability.