不仅刺激性质引起条件性恐惧，而且预测水平也能引起条件性恐惧，那么二者之间存什么样的分离与交互作用呢？对此，采用事件相关电位，把预测水平分为可预测与不可预测两个水平，刺激性质分为中性刺激和负性刺激。采用2 × 2被试内实验设计，探索预测水平、刺激性质在条件性恐惧形成中的分离效应。实验结果发现：在可预测水平下，刺激性质之间ERP波形在加工早期就存在显著差异，出现了分离；在不可预测水平下，刺激性质之间的ERP波形在加工早期差异不显著；不同刺激性质在不同预测水平上ERP波形差异显著。这些结果表明预测水平、刺激性质在条件性恐惧形成中存在分离与交互效应。
Conditioned fear is caused by not only stimulus properties but also prediction level. Then what dissociation and interaction are between prediction levels and stimulus properties? Using event-related potentials (ERP), prediction levels were divided as unprediction and prediction; stimulus properties were divided as neutral and aversion stimulus. Use 2 × 2 within-subjects experimental design, to explore the dissociation between prediction levels and stimulus properties in the acquisition phase of conditioned fear. These data found that: the ERP between the stimulus properties had a significant difference at an early stage of processing under prediction; the ERP between the stimulus properties did not have a significant difference at an early stage of processing under unprediction; the ERP of different stimulus properties had a significant difference under different prediction levels. The results showed there were dissociation and interaction between prediction levels and stimulus properties in conditioned fear.