The contingent negative variation and individual differences in smoking behaviour

Abstract

The aim of the experiment was to examine evidence for a relationship between extraversion, smoking effects, and event related cortical measures. Sixteen extraverted and 16 introverted smokers, drawn from the general population, and matched for age, sex and neuroticism, participated as paid volunteers. Vertex EEG and eye movements were recorded during an S 1–S 2–MR paradigm. Foreperiod duration varied between a regular interval series (1.25 sec) and an irregular interval series (1.25/4.00 sec) with both simple and choice reaction time conditions. Eight artefact free trials were averaged from each condition for each subject, within both a sham smoking and a real smoking session. Analysis of variance revealed significant personality group by sessions interaction effects for both CNV and VER measures. Peak CNV amplitude was found to be greater in extraverts during real smoking and greater in introverts during sham smoking sessions which supported previous findings relating to the biphasic arousing properties of smoking. However, component measures taken on the CNV waveforms under the longer foreperiod interval, indicated differences in shape as well as amplitude of the CNV responses elicited under smoking. In extraverted smokers the early ‘orienting’ component of the CNV was more pronounced during sham smoking, but during real smoking the later ‘E’ wave component became more prominent. Introverted smokers on the other hand showed a decrease in ‘E’ wave amplitude from sham to real smoking sessions. A model involving personality differences in attentional strategies employed during sham and real smoking sessions is proposed to account for CNV morphological differences. Group differences in EEG, performance and puff volume measures over foreperiod conditions suggested that smoking accompanied enhanced stimulus selectivity in introverts, but enhanced response preparation in extraverts. Possible brain mechanisms responsible for the interaction between nicotine effects and personality specific attentional strategies are discussed.