不同程度吸烟者内隐态度测量范式下的ERP研究

采用内隐联想测验的WIAT范式研究不同程度吸烟者的内隐态度，并用ERP技术探讨吸烟者相容与不相容任务的脑内时程变化。WIAT结果发现，只有程度深组对吸烟持明显消极态度。ERP结果表明，在不相容任务中程度深组诱发了比程度浅组更大的P2，说明程度深组对与积极相联的吸烟词早期注意增强。同时程度深组的不相容任务诱发了比相容任务更大的LPC，提示程度深组晚期对吸烟词有正性情绪加工。

An ERP Study of Implicit Attitude towards Smoking for Different Degree Smokers

The present study used Implicit Association Test to investigate the implicit attitude of different degree of male smokers towards smoking words, and used Event-related brain potentials (ERPs) to investigate the congruent pairings and incongruent pairings in neural processing. We explored the combined influence for smoking behavior by cognitive factor and physiological mechanism. We used the Single-Target IAT to collect behavior results. The Single-Target IAT consisted of five phases: (1) practice sorting attribute stimulus to the attribute categories (positive vs. negative); (2) practice critical combined sorting of all stimulus to both the target and the attribute categories; (3) critical combined sorting of all stimulus to both the target and the attribute categories; (4) practice critical combined sorting with reversed response requirements for the target; (5) critical combined sorting with reversed response requirements for the target. In general, responses tend to be faster when the two categories that share a response key in the combined phases are somehow associated than when they are not. The difference in reaction time (RTs) between phase 3 and 5 reflects whether smoking is associated more strongly with positive or negative. Brain electrical activity was recorded from 64 scalp sites using tin electrodes mounted in an elastic cap (Brain Product), with the reference on the left and right mastoids. The vertical electrooculogram (EOG) was recorded with electrodes placed above and below the left eye. Inter-electrode impedance was maintained <5 kΩ. The EEG and EOG were amplified using a 0.05-100 Hz bandpass and continuously sampled at 500Hz/channel for off-line analysis. Eye movement artifacts (blinks and eye movements) were rejected offline. EEG to different types of responses was analyzed after the stimulus appeared. The averaged epoch for ERP was 1,000 ms including 800 ms poststimulus and 200 ms prestimulus. Only EEGs to correct responses related to the target words were analyzed. Based on the grand averaged map and topographical map (see Fig. 1, Fig. 2), 18 electrode sites (Fp1, Fpz, Fp2, F7, Fz, F8, F1, F2, FCz, CP3, CPz, CP4, P3, Pz, P4, O1, and O2) were chosen for three-way repeated measures analyses of variance (ANOVA). The ANOVA factors were task type (congruent pairings, incongruent pairings), smoking degree and electrode site. For all analyses, p-value was corrected for deviations according to the Greenhouse Geisser method. After analyzing, we obtained the following conclusions: (1) As the behavior results suggested, multiple-factor repeated measures ANOVA revealed significant difference between congruent pairings and incongruent pairings of heavy smoking participants. [ F (1，14)= 6.750, p < 0.05]. Only the implicit attitude towards smoking words of the heavy smokers was negative significantly. (2) As the ERP results suggested, P200 only showed higher amplitudes in response to heavy smokers for incongruent pairings than light smokers. LPC showed higher amplitudes in 700-800ms in response to incongruent pairings for heavy smokers than congruent pairings.