Abstract: Prospective memory is remembering to do something at a future time. In this study we adopt dual task paradigm and used ERPs to investigate how the difficulties of the ongoing activity affect the strategically processing of prospective memory. The ongoing activity is tested by n-back task, when the prospective cues were presented. The participant should do the prospective task. The experiment included three conditions: control condition, low difficulty(1-back PM)condition, and high difficulty(3-back PM)condition. The behavior date suggested that the reaction time of the ongoing task is longer than prospective task, and as the difficulties increasing, the RT is increasing. The ERPs data indicate that the latency of the N300 in higher difficulty ongoing task is shorter than that is in lower difficulty ongoing task, whereas the peak amplitude of N300 in higher difficulty condition is smaller than lower difficulty condition. The average amplitude of the prospective positive in higher difficulty ongoing activity condition is larger than that is in lower difficulty ongoing task condition. These results suggested that the prospective memory processing needs cognitive resource, and that the cognitive resource allocation is moderated by the difficulty of ongoing activity. When the difficulty of ongoing activity is increasing, the prospective cue is processed with priority, and this reults that less cognitive resource are engaged in the target monitor. However, in the phase of prospective cue identifying and intention retrieval, more cognitive resources are engaged in identifying the prospective cue to ensure that the prospective memory is completed smoothly.

Key words: prospective memory, ongoing activity, strategically processing, N300, prospective positive

摘要： 采用事件相关电位技术（ERPs）,用双任务加工范式探讨背景任务的难度对前瞻记忆策略加工的影响。行为结果表明,背景任务的反应时显著长于前瞻任务,随着任务难度的增大,被试的反应时增加;脑电结果表明,前瞻线索诱发的N300的潜伏期在高难度任务条件下短于低难度任务条件,而波幅在高难度任务条件下小于低难度任务条件。前瞻线索诱发的前瞻正波的波幅在高难度任务条件下高于低难度任务条件。这一结果表明,背景任务的特征调节了前瞻记忆的加工策略。

关键词: 前瞻记忆, 背景任务, 策略加工, N300, 前瞻正波