Zahedi Anoushiravan, Stuermer Birgit, Hatami Javad, Rostami Reza, Sommer Werner
University of Tehran, Iran.
International Psychoanalytic University Berlin, Germany.
Neuropsychologia. 2017 Feb;96:70-77. doi: 10.1016/j.neuropsychologia.2017.01.006. Epub 2017 Jan 7.
The classic Stroop task demonstrates the persistent and automatic effects of the meaning of color words that are very hard to inhibit when the task is to name the word color. Post-hypnotic instructions may enable highly-hypnotizable participants to inhibit the automatic access to word meaning. Here we compared the consequences of hypnosis alone and hypnosis with post-hypnotic instructions on the Stroop effect and its facilitation and inhibition components. Importantly, we studied the mechanisms of the hypnosis effects at the neural level by analyzing EEG frequencies. Highly hypnotizable participants performed the Stroop task in a counterbalanced design following (1) post-hypnotic suggestions that words had lost their meaning, (2) after hypnosis alone, and (3) in a control condition without hypnosis. The overall Stroop effect and both its facilitation and interference components, were not significant after the post-hypnotic suggestion but in both other conditions. Hypnosis alone neither affected the Stroop effect nor - in contrast to some previous reports and claims - overall performance. EEG recorded during the Stroop task showed a significant increase in both frontal theta and frontal beta power when participants were under the impact of post-hypnotic suggestions, in comparison to the two other sessions. Together, these findings indicate that post-hypnotic suggestions - but not hypnosis alone - are powerful tools for eliciting top down processes. Our EEG findings could be interpreted as clue that this is due to the investment of additional cognitive control.
经典的斯特鲁普任务表明，当任务是说出单词颜色时，颜色词意义的影响持续且自动，极难被抑制。催眠后指令可能使高度易受催眠的参与者抑制对单词意义的自动提取。在此，我们比较了单纯催眠以及催眠结合催眠后指令对斯特鲁普效应及其促进和抑制成分的影响。重要的是，我们通过分析脑电图频率，在神经层面研究了催眠效应的机制。高度易受催眠的参与者按照平衡设计执行斯特鲁普任务，依次为：(1) 接受单词失去意义的催眠后暗示；(2) 仅接受催眠后；(3) 在无催眠的对照条件下。催眠后暗示后，整体斯特鲁普效应及其促进和干扰成分均不显著，但在其他两种条件下显著。与一些先前的报告和说法相反，仅催眠既不影响斯特鲁普效应，也不影响整体表现。与其他两个阶段相比，在斯特鲁普任务期间记录的脑电图显示，当参与者受到催眠后暗示影响时，额叶θ波和额叶β波功率均显著增加。总之，这些发现表明，催眠后暗示——而非仅催眠——是引发自上而下加工过程的有力工具。我们的脑电图研究结果可以解释为这是由于额外认知控制的投入。
