Cipolli Carlo, Fagioli Igino, Mazzetti Michela, Tuozzi Giovanni
Department of Psychology, University of Bologna, Bologna, Italy.
J Sleep Res. 2004 Dec;13(4):317-26. doi: 10.1111/j.1365-2869.2004.00420.x.
Presleep stimuli to be retained for further recall is often incorporated into dream contents. To establish whether processing for insertion into dream contents may improve consolidation, we compared the retention rate at delayed recall of contents resulting from incorporation of presleep sentence-stimuli with those of other contents of the same dream experiences. We hypothesized that association with a cognitive task of recall facilitates access to recently acquired items of declarative knowledge such as presleep stimuli, and triggers the deep elaboration of their semantic features, which involves rehearsal. Twelve subjects were given a task of delayed recall for three nonsense sentences delivered once a time before each of the sleep (re-)onsets over an experimental night. After each awakening in rapid eye movement sleep, subjects were asked to report dream experience and recall the sentence to be retained. In the morning, after spontaneous awakening, subjects were unexpectedly requested to again report their dream experiences and to recall the stimuli. Two pairs of judges independently identified possible incorporations of the stimuli, and parsed dream reports into propositional content units. The proportion of night reports with at least one incorporation of the stimulus delivered (i.e. valid incorporations) was higher than that of reports with contents similar to a stimulus(-i) not yet delivered (forward pseudo-incorporations) or delivered prior to an earlier sleep period (backward pseudo-incorporations). The proportion of content units common to night and morning reports (considered to be better consolidated) was significantly higher for incorporated contents than for other contents, including pseudo-incorporated contents. Instead, the retention at morning recall of words of sentence-stimuli corresponding to incorporated contents was not significantly higher than that of other words. The better retention of incorporated contents provides a partial confirmation (that is, limited to the output of the processing) that a generation effect, which benefits retention of actively processed information, is operative during sleep as well as in waking.
为了便于日后回忆而在睡前呈现的刺激往往会融入梦境内容。为了确定融入梦境内容的处理过程是否能改善记忆巩固，我们比较了因融入睡前句子刺激而产生的内容在延迟回忆时的保留率与同一梦境经历中其他内容的保留率。我们假设，与回忆的认知任务建立关联有助于获取最近习得的陈述性知识项目，如睡前刺激，并触发对其语义特征的深度加工，这涉及复述。在一个实验夜间，每次睡眠（重新）开始前，给12名受试者一项延迟回忆任务，即对三个无意义句子进行回忆。在快速眼动睡眠中每次醒来后，要求受试者报告梦境经历并回忆要保留的句子。早晨，在自然醒来后，意外要求受试者再次报告他们的梦境经历并回忆刺激内容。两组独立的评判员确定刺激内容可能的融入情况，并将梦境报告解析为命题内容单元。至少有一次融入所呈现刺激内容的夜间报告比例（即有效融入）高于那些包含与尚未呈现的刺激（正向伪融入）或在更早睡眠期之前呈现的刺激（反向伪融入）相似内容的报告比例。对于融入内容，夜间和早晨报告中共同的内容单元比例（被认为巩固得更好）显著高于其他内容，包括伪融入内容。相反，早晨回忆时与融入内容相对应的句子刺激中的单词保留率并不显著高于其他单词。融入内容更好的保留率部分证实了（即仅限于加工输出）生成效应在睡眠和清醒时同样起作用，该效应有利于积极加工信息的保留。
