回想、熟悉性与启动在编码过程的认知神经机制

为了探究基于回想和熟悉性的外显记忆及基于启动的内隐记忆在编码阶段的认知加工差异, 该文采用事件相关电位(ERP)技术, 并结合迫选再认测验和相继记忆(Dm)范式, 把学习项目分为四类：随后记住、随后知道、随后启动及随后忘记。结果表明, 与启动关联的Dm效应表现在刺激后700 ms开始的中央区, 随后启动比随后忘记更为负走向, 即负走向的Dm效应; 与回想关联的Dm效应表现为从400 ms开始的右前额区正走向Dm效应以及800 ms开始的枕区负走向Dm效应, 而与熟悉性关联的Dm效应表现在300~400 ms的前额区及500~600 ms的顶区正走向Dm效应。为了进一步确定这些Dm效应与不同记忆类型的关联, 第二个实验中在编码阶段同时设置了干扰任务, 以探究编码干扰下Dm效应的变化, 结果发现, 在编码干扰的作用下, 与启动关联的中央区负走向Dm效应仍有存在, 而与两种外显记忆：回想和熟悉性关联的Dm效应发生了不同的变化, 即在编码干扰下并未发现任何与回想关联的Dm效应, 但与熟悉性关联的正走向Dm效应仍有存在, 主要表现在600~800 ms的右侧额区。综合这些结果, 表明回想、熟悉性与启动在编码阶段的脑机制应该存在着分离的现象。     

内隐面孔记忆的编码机制*

为了探究内隐面孔再认在记忆形成过程中的认知加工状态,该实验以陌生面孔为刺激,采用事件相关电位(ERP)技术,并结合相继记忆(Dm)范式和迫选再认测验,把学习阶段的面孔分为相继记住、相继启动及相继忘记三类,以相继记住与相继启动的 ERP 差异为外显记忆 Dm 效应,以相继启动与相继忘记的差异为内隐记忆的 Dm效应。结果表明,内隐记忆表现为400~500 ms额中央区负走向的 Dm效应,可能反映了额叶皮层对信息的精加工过程,而外显记忆表现为400 ms开始顶区正走向的Dm效应,可能反映了记忆系统对加工后信息的自动登记过程。由此推测,只有经过额叶加工并被内侧颞叶自动登记的信息,随后才能被有意识地提取出来,而未进入内侧颞叶的信息在随后测验中不可能产生有意识地记忆提取现象,但储存的知觉表征可能触发微弱的记忆痕迹,从而产生内隐面孔记忆。     

内隐记忆和外显记忆的脑机制分离：面孔再认的ERP研究

该研究采用“学习-再认”实验范式探讨面孔领域的内隐记忆与外显记忆之间的关系。学习阶段采用选择性注意任务,让被试加工面孔上的字来控制对面孔的加工水平,再认阶段采用新旧判断,分析再认出旧面孔与新面孔(外显记忆),以及未再认旧面孔与新面孔(内隐记忆)的ERPs差异。结果表明,在单一的再认过程中,外显记忆和内隐记忆的脑机制产生了分离,外显记忆从刺激后400ms开始,主要表现在前额区和额区,而内隐记忆主要表现在刺激后300~500ms的中央区和顶区。该结果与以往在词领域研究中得到的结果极为类似,表明两种记忆类型在各个刺激领域之间存在着共同性     

提取方式对相继记忆效应的影响

采用学习－测验（自由回忆和再认）研究范式和事件相关电位方法,研究图形的相继记忆效应（Dm效应）。14名大学生作为研究被试,根据其测验成绩将图片分为记住和未记住两类,对相应编码过程的ERPs进行分析。结果表明：⑴行为上,再认的平均击中率显著高于自由回忆;⑵脑电活动上,在刺激出现后400~700ms编码过程中记住项目的ERPs更正于未记住项目的ERPs;同时两种测验方式Dm效应的脑区分布不同,自由回忆主要分布在额区,再认主要分布在中央区和顶区,且在500~600ms自由回忆有左侧优势。这些结果表明,两种提取方式对Dm效应有不同的影响,这一结果预示自由回忆和再认的编码过程可能有不同的神经生理机制。     

字表法定向遗忘对内隐记忆测验的影响

字表法定向遗忘是否影响内隐记忆测验,一直是记忆心理学家关注的焦点.本研究选取低频词语作为实验材料,引入指示符变量(记住、遗忘).以词干回忆和词干补笔分别作为外显和内隐记忆测验,考察字表法定向遗忘对内隐记忆测验的影响.结果发现:(1)内隐和外显记忆测验中都出现了显著的字表法定向遗忘效应;(2)字表法定向遗忘效应的机制应该是提取抑制,即要求遗忘的项目在提取时受到抑制而使记住项目的成绩更为突出,而不是偏好对记住项目复述的结果.     

编码与提取干扰对内隐和外显记忆的非对称性影响

以往研究表明在外显记忆中,编码与提取加工存在着非对称性,但在内隐记忆中,二者的关系并不明确,因此实验采用“学习-再认”范式,考察在编码或提取中分别附加的干扰任务对词汇判断或再认产生的影响。结果证实编码与提取干扰对内隐或外显记忆都具有非对称性的影响,但又存在着差异,即编码干扰会导致随后外显记忆成绩显著减少,而提取干扰对其影响较小,相反,编码干扰对随后内隐测验中启动效应的影响较小,但提取干扰会破坏启动效应,从而为内隐记忆和外显记忆的分离提供了进一步的证据     

FN400效应:外显记忆测量中的概念启动加工

概念启动与熟悉性的研究是近年来内隐记忆与外显记忆神经机制研究的焦点领域之一。双加工理论支持者认为额区300~500 ms(FN400)新旧效应指示熟悉性。单加工理论支持者认为,双加工理论支持者在得出FN400效应指示熟悉性的结论时,没有考虑内隐记忆尤其是概念启动对外显记忆的污染。通过一系列分离熟悉性和概念启动的研究,Paller等人证明了FN400效应指示的是概念启动而不是熟悉性,并且,熟悉性由顶区500~800 ms(LPC)新旧效应来指示。目前,关于FN400效应反映了何种记忆加工仍然存在争议,未来研究需要探索分离熟悉性和概念启动的新方法,并进一步考察流畅性对熟悉性影响的神经机制。     

提取干扰对内隐记忆的影响

以往研究多认同内隐记忆不会受到干扰的影响,但主要集中于编码时的干扰不会影响随后的内隐记忆提取成绩,而对于提取时的干扰是否也不会影响内隐记忆成绩仍存在疑义。该文在实验1采用学习-测验范式,通过在提取阶段设置同时干扰任务进一步考察提取干扰与内隐记忆的关系,结果表明提取干扰下并未发现明显的启动效应,即提取干扰破坏了内隐记忆。为进一步探讨内隐记忆的提取干扰效应是否源于记忆与干扰刺激同时呈现所引起的知觉表征竞争,实验2改变了记忆与干扰刺激的呈现顺序,结果表明不论干扰刺激在记忆项目之前或之后呈现,启动效应均受到影响。相比之下,提取干扰对再认成绩的影响并不明显(实验3)。上述结果表明,内隐记忆的提取干扰效应是源于一般认知资源的竞争,在提取过程中任何能够产生认知资源竞争的变量设置都可能会削减内隐测验中的启动效应。     

12-13岁儿童数字编码与提取的ERP研究

采用学习与再认测验范式,研究儿童数字编码与提取的神经机制。18名12-13岁儿童作为研究被试,要求在测验阶段对数字是否学过进行判断,并记录编码与提取阶段的ERPs,然后考察旧数字是否成功提取在编码阶段形成相应的相继记忆(Dm)效应,同时,考察正确判断的旧数字和新数字在提取阶段形成相应的旧/新(old/new)效应。结果表明,编码阶段,Dm效应出现在400-700ms的枕区、顶区和中央区,正确再认数字的正波波幅明显大于再认错误数字的正波波幅;提取阶段,在400-500ms,枕区和顶区存在显著的old/new效应,在500-700 ms内的顶区和中央区存在显著的old/new效应,尤以中央区为主,正确再认旧数字的正波波幅明显大于正确再认新数字的正波波幅。这些结果说明,认知数字与面孔、图片的Dm效应和old/new效应在时、空均有所不同。     

不同加工与记忆编码关系的ERP研究

通过事件相关电位(ERPs)记录,探讨了深、浅2种加工与记忆编码的相互关系。研究结果表明,（1）在深、浅两种加工条件下,首次使用汉字材料,获得了ERP相继记忆效应（Dm),随后再认正确的ERPs比随后再认不正确的ERPs有更大的晚正成分。（2）深加工的Dm效应始于N2波的前支（230－280ms)和N2波之后（395－800ms);而浅加工的Dm效应发生在345－490ms之间。深、浅加工的Dm效 涉及不同的脑区,这一结果支持深、浅两种加工的Dm效应可能是分离的结论。     

Retrieval of concrete words involves more contextual information than abstract words: multiple components for the concreteness effect

The current study used the directed forgetting paradigm in implicit and explicit memory to investigate the concreteness effect. Event-related potentials (ERPs) were recorded to explore the neural basis of this phenomenon. The behavioral results showed a clear concreteness effect in both implicit and explicit memory tests; participants responded significantly faster to concrete words than to abstract words. The ERP results revealed a concreteness effect (N400) in both the encoding and retrieval phases. In addition, behavioral and ERP results showed an interaction between word concreteness and memory instruction (to-be-forgotten vs. to-be-remembered) in the late epoch of the explicit retrieval phase, revealing a significant concreteness effect only under the to-be-remembered instruction condition. This concreteness effect was realized as an increased P600-like component in response to concrete words relative to abstract words, likely reflecting retrieval of contextual details. The time course of the concreteness effect suggests advantages of concrete words over abstract words due to greater contextual information.     

Word priming without awareness: A new approach to circumvent explicit memory contamination

A major methodological limitation arising in the experimental study of implicit memory is that tasks that are characterized as implicit memory tests can be seriously contaminated by the use of covert explicit memory strategies. Given the evidence indicating that brief presentation of words (below the awareness threshold of subjects) can produce semantic priming, we wondered whether rapid visual presentation of primed words might provide an avenue to produce word priming without explicit memory contamination. Normal subjects were tested for word priming on a speeded category membership decision task. Explicit or implicit encoding procedures were used in four different experiments. Results demonstrated that brief presentation of words can indeed offer a means of producing word priming in absence of explicit recognition or recall of the primed words presented during the study phase. They also showed that such priming is equivalent in degree to the priming measured when using either a conventional implicit memory design or an explicit encoding procedure prior to the study of the primes.     

内隐与外显记忆的编码与提取非对称性关系

实验采用“学习-测验”范式, 考察在编码或提取中分别附加的干扰任务对内隐测验或外显测验中获得的ERP新旧效应产生的影响。结果表明, 在内隐测验中, 编码干扰对随后测验中的ERP新旧效应没有产生影响, 而提取干扰却改变了300~500ms新旧效应的脑区位置, 破坏了500~700ms新旧效应; 与之相反, 在外显测验中, 编码干扰破坏了500~700ms新旧效应, 而提取干扰对这一效应没有产生影响, 即编码与提取干扰对内隐或外显测验中的ERP新旧效应都产生了非对称性的影响, 但又存在着差异, 从而为两种记忆在编码与提取加工的关系上存在的分离现象提供了神经生理方面的证据。     

Capturing conceptual implicit memory: The time it takes to produce an association

Conceptual implicit memory is demonstrated when, in the absence of explicit retrieval, performance on a task requiring conceptual processing benefits more from prior conceptual encoding than from prior nonconceptual encoding. In the present study, we sought to provide an improved measure of conceptual implicit memory by minimizing contamination from explicit retrieval. On a modified word association test, participants free-associated to the actually studied items, with response time to produce any associate serving as the dependent measure. Experiment 1 varied whether words were read or generated at study and showed that generated words were associated to more quickly than were read words. Experiment 2 varied level of processing at study and showed that words processed semantically were associated to more quickly than were words processed nonsemantically. With modifications to ensure its implicit nature, a conceptual implicit test can be consistently affected by the same encoding manipulations as those that affect conceptual explicit memory tests.     

Implicit effects of emotional contexts: An ERP study

Previous recognition memory experiments have demonstrated that the ERPs elicited by correctly recognized test items differ according to whether the items were encoded in an emotionally arousing or an emotionally neutral context. It is not clear, however, whether these ERP differences depend on the explicit recognition of the items. We addressed this question in the present study by contrasting the ERPs elicited by test items encoded in emotionally negative or emotionally neutral study contexts, according to whether the items were correctly recognized or misclassified as new. Recognized items associated with emotional rather than neutral contexts elicited an early positive-going and a later negative-going effect that resembled the effects reported in prior studies. Relative to unrecognized items encoded in neutral contexts, unrecognized items encoded in emotional contexts elicited a sustained, frontal-maximum, positive-going effect that onset at about 200?ms poststimulus. This effect may reflect an influence of emotional arousal on the neural correlates of implicit memory.     

记忆机制中再认的事件相关电位

ERP对于记忆的研究有独到之处,在研究方法是有外显的直接范式和内隐的间接范式,分别表现为ERP新旧效应和重复效应,即在刺激200ms以后的正向偏移.对于记忆提取的ERP效应已有一些理论解释,但在听觉记忆、汉字记忆以及记忆的脑内机制等方面还需要进一步的深入研究.     

外显与内隐记忆的情绪一致性效应

基于Yonelinas等双加工信号检测模型对再认记忆测验中外显记忆与内隐记忆分离的方法,以96名大学生为被试,考察了诱发抑郁与非临床抑郁状态下外显和内隐记忆的情绪一致性效应。结果表明诱发抑郁组和非临床抑郁组对抑郁词的外显记忆成绩显著高于对中性词和愉快词;对抑郁词的内隐记忆成绩亦显著高于对中性词和愉快词,且显著高于控制组对抑郁词的内隐记忆成绩。情绪一致性记忆效应在非临床抑郁个体和诱发抑郁个体的外显和内隐记忆中均存在。