Volberg Gregor, Thomaschke Roland
Institut für Psychologie, Universität Regensburg, Regensburg, Germany.
Institut für Psychologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
Cortex. 2017 Jul;92:261-270. doi: 10.1016/j.cortex.2017.04.019. Epub 2017 May 4.
Human behavior is guided by expectations that facilitate perception of upcoming events or reaction to them. In natural settings expectations are often implicitly based on time, e.g., when making a phone call one would expect to hear either a person answering (earlier) or a voicemail greeting (later). We investigated how time-based expectations can improve performance in the absence of explicit prior information on the pending stimulus or the associated response. Visual stimuli were presented after a characteristic short or long foreperiod, and a forced-choice categorization using either the left or the right hand was required. The electroencephalogram (EEG) revealed a decrease in central 9-12 Hz power over the course of the trial. Moreover, lateralized pre-motor potentials were observed which changed polarity after the short foreperiod. At stimulus onset, amplitudes of pre-motor potentials co-varied with performance, so that higher (more negative) amplitudes were associated with slower responses to unexpected targets. Altogether, the results suggest that implicit time-based expectations entail effector-specific preparatory brain activity, which is inhibited until the expected onset time of the event. Thus, time-based expectations prepare for action.
人类行为受期望的引导，这些期望有助于对即将发生的事件进行感知或对其做出反应。在自然环境中，期望通常隐含地基于时间，例如，打电话时，人们会期望较早听到有人接听或较晚听到语音信箱问候。我们研究了在没有关于待处理刺激或相关反应的明确先验信息的情况下，基于时间的期望如何提高表现。在特征性的短或长预备期后呈现视觉刺激，并要求使用左手或右手进行强制选择分类。脑电图（EEG）显示在试验过程中中央9 - 12赫兹功率下降。此外，观察到侧化的运动前电位，其在短预备期后改变极性。在刺激开始时，运动前电位的振幅与表现共同变化，因此较高（更负）的振幅与对意外目标的较慢反应相关。总之，结果表明基于时间的隐含期望需要效应器特异性的预备脑活动，这种活动在事件的预期开始时间之前被抑制。因此，基于时间的期望为行动做好准备。
