预知任务转换的内源性准备和外源性调节

Endogenous Preparation and Exogenous Adjustment in Task Switching Under Foreknowledge

采用ERP探究在预知条件下任务转换的神经机制。使用“任务转换”实验范式，以汉字（名词/动词）或数字（奇数/偶数）的归类为任务。被试执行任务重复（AA，BB，…）或在两个任务间转换（AB，BA，…），每个任务序列为连续的两个任务（任务1，任务2）。结果发现，任务1中，在刺激呈现后 300ms左右，数、词的转换序列与重复序列出现显著差异；在中央区，320ms左右，任务1中转换序列比重复序列、任务2中转换任务比重复任务都产生一个更为负走向的波。这些结果表明，在预知条件下，简单任务转换的内源性准备可能开始于任务1呈现后300ms左右；内源性准备和外源性调节可能都反映了认知冲突过程，此认知冲突可能是转换代价的主要来源。

Task switching is the basic method in human cognitive activities， and the switching process is an important aspect of executive control， which is responsible for controlling the switching course between two tasks competing for the same cognitive resources in working memory. Switching costs refer to longer reaction times for switching items (e.g.， AB)， as compared to repeating items (e.g.， BB) as an indicator of executive control. The course of switching is involved in both endogenous preparation