基于Think/No-think范式的动机性遗忘研究:行为与脑机制

想/不想范式(Think/No-think,TNT)是基于go/no-go范式提出来的用于研究动机性遗忘过程的实验范式,主要过程是指个体对于记忆的提取抑制可以导致随后该记忆的遗忘。近年来TNT范式的大量行为学研究都一致性地发现记忆提取抑制可以产生负性控制效应,验证了在实验室情境下对动机性遗忘进行研究的可行性。其中,负性控制效应指的是压抑条件的项目相对于基线条件的项目的回忆量有显著降低。关于动机性遗忘发生的神经机制的探讨已积累了大量的研究证据,总结脑电(EEG)和功能核磁共振(f MRI)两个模态的研究,我们提出了动机性遗忘发生的多模态功能网络模型。最后,在该模型的基础上,我们展望了TNT范式未来的研究方向,其中特别注意到同步EEG-f MRI技术的应用有望为我们揭示出记忆提取抑制导致的动机性遗忘发生的动态过程。     

Intentional suppression of unwanted memories grows more difficult as we age

People often encounter reminders to memories that they would prefer not to think about. When this happens, they often try to exclude the unwanted memory from awareness, a process that relies upon inhibitory control. We propose that the ability to regulate awareness of unwanted memories through inhibition declines with advancing age. In two experiments, we examined younger and older adults' ability to intentionally suppress retrieval when repeatedly confronted with reminders to an experience they were instructed to not think about. Older adults exhibited significantly less forgetting of the suppressed items compared to younger adults on a later independent probe test of recall, indicating that older adults failed to inhibit the to-be-avoided memories. These findings demonstrate that the ability to intentionally regulate conscious awareness of unwanted memories through inhibitory control declines with age, highlighting differences in memory control that may be of clinical relevance in the aftermath of unpleasant life events.     

压抑遗忘的影响因素

人在生活中的一些负性经历或无效信息可以通过压抑提取而遗忘,这种遗忘称为压抑遗忘。压抑遗忘不仅受压抑时长、压抑次数、实验材料的情绪效价和唤醒度、期待效应等的影响,还受个体的年龄和精神障碍等的影响。今后应着重考察精神疾病个体记忆控制网络内的连接强度与压抑遗忘的关系,澄清压抑遗忘是否存在补偿机制。     

压抑遗忘的影响因素

人在生活中的一些负性经历或无效信息可以通过压抑提取而遗忘,这种遗忘称为压抑遗忘。压抑遗忘不仅受压抑时长、压抑次数、实验材料的情绪效价和唤醒度、期待效应等的影响,还受个体的年龄和精神障碍等的影响。今后应着重考察精神疾病个体记忆控制网络内的连接强度与压抑遗忘的关系,澄清压抑遗忘是否存在补偿机制。     

Thought suppression,intelligence, and working memory capacity

The importance of individual differences in intelligence and working memory capacity in predicting the ability to intentionally suppress thoughts was investigated. Sixty participants completed a thought suppression task, and measures of working memory capacity (OSPAN), fluid intelligence (Raven's Matrices), and crystallised intelligence (the National Adult Reading Test). As predicted, the results indicated that more effective thought suppression was independently related to higher working memory capacity and greater fluid intelligence, but was unrelated to crystallised intelligence. The findings have theoretical implications for understanding the mechanisms underlying a failure to inhibit unwanted intrusions and clinical implications for disorders involving high levels of intrusive thoughts and memories.     

抑制引起的遗忘及其神经机制

当面对不愉快的提醒时, 人们通常会试图阻止那些不想要的记忆出现在脑海中。先前的研究表明, 抑制不想要的记忆的检索会降低这些记忆的可及性, 引起遗忘, 这一效应称为抑制引起的遗忘(suppression- induced forgetting, SIF)。SIF的神经机制涉及右背外侧前额叶皮层和额中回的激活增加, 以及海马的激活受到抑制。SIF的程度受记忆材料的情绪效价、个体的病理性情绪状态和训练的影响。未来研究应在深入了解SIF神经机制的基础上, 考虑如何提高临床病理性记忆的SIF效果, 以达到治疗目的。     

跨视听通道主动遗忘的期待加工与抑制控制过程：来自ERPs的证据

基于视觉通道的研究表明,人们可以通过主动抑制记忆提取而实现遗忘。但目前对跨通道的主动遗忘尚缺乏探讨。本研究以声音为记忆线索,以文字为目标记忆,采用“想/不想”范式,探究主动遗忘在跨视听通道条件下的可行性。结果发现,“不想”条件下目标记忆的回忆率低于基线条件,主动遗忘发生。此外,我们通过分离任务指令和记忆线索的呈现时间,在中央区域的ERP中发现了记忆抑制的期待效应;并在额叶观察到“不想”条件下晚期正成分的增强,反映了持续的抑制控制过程。本研究不但验证了跨视听通道主动遗忘的可能性,而且第一次从ERPs角度分离了跨通道遗忘相关的期待加工和抑制控制过程。     

The costs of suppressing stressful memories

We investigated the costs of suppressing emotional and nonemotional memories, as evidenced in response times on a concurrent sentence verification task with three levels of syntactic complexity. Participants suppressing memories of personal negative experiences (n=26) had slower response times compared to the control group (n=23) and to participants suppressing nonemotional memories (n=25) particularly on the most complex sentences. Participants suppressing nonpersonal negative experiences (n=26) did not differ from either of the other two suppression groups. Suppression failures did not differ between conditions, but failures during the sentence task were related to the intrusiveness of the memory being suppressed. The findings indicate that different kinds of memories have different suppression costs and that even successful thought suppression can impair performance on concurrent tasks, supporting Wegner's ironic processing model in which suppression attempts must compete with other ongoing tasks for scarce mental resources.     

Memory suppression can help people “unlearn” behavioral responses—but only for nonemotional memories

When encountering reminders of memories that we prefer not to think about, we often try to exclude those memories from awareness. Past studies have revealed that such suppression attempts can reduce the subsequent recollection of unwanted memories. In the present study, we examined whether the inhibitory effects extend even to associated behavioral responses. Participants learned cue–target pairs for emotional and nonemotional targets and were additionally trained in behavioral responses for each cue. Afterward, they were shown the cues and instructed either to think or to avoid thinking about the targets without performing any behaviors. In a final test phase, behavioral performance was tested for all of the cues. When the targets were neutral, participants’ attempts to avoid retrieval reduced accuracy and increased reaction times in generating behavioral responses associated with cues. By contrast, behavioral performance was not affected by suppression attempts when the targets were emotional. These results indicate that controlling unwanted recollection is powerful enough to inhibit associated behavioral responses—but only for nonemotional memories.     

The impact of retrieval suppression on conceptual implicit memory

ABSTRACT

When people suppress retrieval of episodic memories, it can induce forgetting on later direct tests of memory for those events. Recent reports indicate that suppressing retrieval affects less conscious, unintentional retrieval of unwanted memories as well, at least on perceptually-oriented indirect tests. In the current study we examined how suppressing retrieval affects conceptual implicit memory for the suppressed content, using a category verification task. Participants studied cue-target words pairs in which the targets were exemplars of 22 semantic categories, such as vegetables or occupations. They then repeatedly retrieved or suppressed the targets in response to the cues for some of those pairs. Afterwards, they were exposed to the targets intermixed with novel items, one at a time, and asked to verify the membership of each of the words in a semantic category, as quickly as possible. Judgment response times to studied words were faster than to unstudied exemplars, reflecting repetition priming, as has been previously observed. Strikingly, the beneficial effects of prior exposure on response time were eliminated for targets that had been suppressed. Follow-up explicit memory tests also demonstrated that retrieval suppression continued to disrupt episodic recall for the items that had been just been re-exposed on the category verification test. These findings support the contention that the effects of retrieval suppression are not limited to episodic memory, but also affect indirect expressions of those memories on conceptually oriented tests, raising the possibility that underlying semantic representations of suppressed content are affected.     

Cue-type manipulation dissociates two types of task set inhibition: backward inhibition and competitor rule suppression

Backward inhibition (BI) reflects the suppression of a recently abandoned task set to allow for smooth transition to a new task even when the rules do not generate a response conflict. Competitor rule suppression (CRS) reflects the inhibition/suppression of irrelevant task rules when these rules generate a response conflict even if they have not recently been abandoned. We assessed whether BI and CRS are differentially affected by the difficulty in retrieving category-response mappings from memory. Retrieval demands were manipulated via the information provided by the task cues, which either indicated the relevant dimension (dimension cues; “color”) or the relevant dimension with its category-to-key mapping (mapping cues; “red green”, indicating that “red” and “green” go with the left/right responses, respectively). CRS was larger with dimension compared to mapping cues when cue-type varied between groups and was larger after trials involving dimension cues when cue-type varied on a trial-by-trial basis. In contrast, BI was not influenced by cue-type. These results suggest that task switching involve at least two distinct inhibitory processes, with CRS being related to the ease of retrieval of category-response mappings from memory.     

Individual differences in the suppression of unwanted memories: the executive deficit hypothesis

When confronted with reminders to an unpleasant memory, people often try to prevent the unwanted memory from coming to mind. In this article, we review behavioral and neurocognitive evidence concerning the consequences of exerting such control over memory retrieval. This work indicates that suppressing retrieval is accomplished by control mechanisms that inhibit the unwanted memories, making them harder to recall later, even when desired. This process engages executive control mechanisms mediated by the lateral prefrontal cortex to terminate recollection-related activity in the hippocampus. Together, these findings specify a neurocognitive model of how memory control operates, suggesting that executive control may be an important means of down-regulating intrusive memories over time. We conclude by proposing that individual differences in the regulation of intrusive memories in the aftermath of trauma may be mediated by pre-existing differences in executive control ability. In support of this executive deficit hypothesis, we review the recent work indicating links between executive control ability and memory suppression.     

自我参照对情绪性记忆定向遗忘的影响

关于自我参照效应的研究大多从信息编码角度考察自我参照的加工优势, 但作为记忆过程的另一重要方面, 自我参照对遗忘影响的研究较少。遗忘自身经历的情绪性记忆是日常生活中的常见现象。研究采用项目法定向遗忘范式(item-method directed forgetting)考察了自我参照对情绪性记忆定向遗忘的影响。实验一和实验二的结果都表明参照方式会影响定向遗忘：自我参照条件下的材料会发生定向遗忘; 而他人参照条件下的材料不会发生定向遗忘, 两种参照方式下材料间区辨性的不同是导致这一现象的原因。此外, 实验二采用回忆测试发现：自我参照对不同效价的情绪性记忆定向遗忘产生了不同影响, 而自我提升(self-enhancement)动机在其中起着重要的调节作用。     

情绪性记忆的主动遗忘

情绪性记忆的主动遗忘, 是指人们有意识地主动地遗忘带有情绪色彩的记忆内容, 但更多的是那些带来痛苦的负性情绪性记忆。主动遗忘又分为定向遗忘和压抑遗忘, 项目法和字表法是实验室中研究定向遗忘的主要方法, 而白熊任务和TNT任务是研究压抑遗忘的主要范式, 研究者们围绕两种遗忘做了大量研究。未来的研究应更关注情绪性记忆遗忘的不同心理机制, 不同研究范式与心理机制的交互作用, 情绪性记忆遗忘的个体差异, 情绪性记忆遗忘中事件遗忘和情绪反应遗忘的分离等 问题。     

Age differences in memory control: evidence from updating and retrieval-practice tasks

Some contemporary approaches suggest that inhibitory mechanisms play an important role in cognitive development. In addition, several authors distinguish between intentional and unintentional inhibitory processes in cognition. We report two experiments aimed at exploring possible developmental changes in these two types of inhibitory mechanisms. In Experiment 1, an updating task was used. This task requires that participants intentionally suppress irrelevant information from working memory. In Experiment 2, the retrieval-practice task was used. Retrieval practice of a subset of studied items is thought to involve unintentional inhibitory processes to overcome interference from competing memories. As a result, suppressed items become forgotten in a later memory test. Results of the experiments indicated that younger children (8) were less efficient than older children (12) and adults at intentionally suppressing information (updating task). However, when the task required unintentional inhibition of competing items (retrieval-practice task), this developmental trend was not found and children and adults showed similar levels of retrieval-induced forgetting. The results are discussed in terms of the development of efficient inhibition and the distinction between intentional and unintentional inhibitions.     

Forget about the future: effects of thought suppression on memory for imaginary emotional episodes

Whether intentional suppression of an unpleasant or unwanted memory reduces the ability to recall that memory subsequently is a contested issue in contemporary memory research. Building on findings that similar processes are recruited when individuals remember the past and imagine the future, we measured the effects of thought suppression on memory for imagined future scenarios. Thought suppression reduced the ability to recall emotionally negative scenarios, but not those that were emotionally positive. This finding suggests that intentionally avoiding thoughts about emotionally negative episodes may inhibit representations of those memories, progressively reducing their availability to recall.     

Retrieval process of overgeneral memory and the capture and executive control hypothesis: using Autobiographical Memory Test with thought sampling

ABSTRACT

The retrieval process for underlying overgeneral autobiographical memory remains unclear. In this study, we identified what leads to self-referential and categoric thoughts and examined the influence error-monitoring ability has on the reporting of categoric memories. We also examined whether cue self-relevance and/or executive control task performance are related to the number of specific memories reported. Using thought sampling, 94 college students completed the Autobiographical Memory Test, as well as a verbal fluency task and a depression scale. The results indicated that depressive symptoms and negative highly self-relevant cues were associated with self-referential/categoric thoughts during memory retrieval. Further, preceding self-referential/categoric thoughts and low error-monitoring ability predicted immediate after-reporting of categoric memories. Simultaneously, highly self-relevant cues and executive control task performance predicted the reporting of many specific memories. Subdividing the retrieval process and examining the process involved in depression are essential.     

Inhibitory and working memory demands of the day–night task in children

Gerstadt, Hong, and Diamond (1994) investigated the development of inhibitory control in children aged 3½ – 7 years using the day–night task. In two studies we build on Gerstadt et al.'s findings with a measure of inhibitory control that can be used throughout childhood. In Study 1 (twenty‐four 3½‐year‐olds and sixteen 5‐year‐olds) we modified Gerstadt et al.'s day–night task. Using this modified task we obtained further evidence for the development of inhibitory control in children between 3½ and 5‐years‐old. We also obtained data suggestive of more moderate working memory development. In Study 2 we tested 84 children aged between 3½ and 11 years. The aim was to determine how much inhibition and working memory taxed children of different ages. We obtained evidence that inhibitory demands were high and that inhibitory development was non‐linear, with rapid improvements in children between 3½ and 5 years and only modest improvements thereafter. In contrast, working memory demands were low and working memory development was more linear. We interpret these findings as evidence that working memory has relatively little impact on performance in our modified version of the day–night task.     

The development of automatic and controlled inhibitory retrieval processes in true and false recall

In three experiments, we investigated the role of automatic and controlled inhibitory retrieval processes in true and false memory development in children and adults. Experiment 1 incorporated a directed forgetting task to examine controlled retrieval inhibition. Experiments 2 and 3 used a part-set cue and retrieval practice task to examine automatic retrieval inhibition. In the first experiment, the forget cue had no effect on false recall for adults but reduced false recall for children. In Experiments 2 and 3, both tasks caused retrieval impairments for true and false recall, and this occurred for all age groups. Implicit inhibition, which occurs outside of our conscious control, appears early in childhood. However, because young children do not process false memories as automatically as adults, explicit inhibition can reduce false memory output.     

Affective evidence that inhibition is involved in separating accessory representations from active representations in visual working memory

ABSTRACT

The multiple state theory of working memory suggests that representations are divided into two states: focused-on active representations and accessory memories held for later use. Here we tested two competing hypotheses regarding the neurocognitive mechanisms responsible for this separation: (1) that accessory memories undergo inhibition or (2) that accessory memories are amplified less than active representations. We explored whether accessory memories undergo affective devaluation, a known index of the involvement of inhibition in a visual task. On each trial participants memorized four items, were cued to focus on one, and then completed a visual search or an affective evaluation task. While search distractors matching the colour of an active item slowed search, those matching an accessory memory did not, replicating previous findings that only active items guide search. Also, accessory items were affectively devalued compared to baseline and active items, supporting the hypothesis that accessory memories undergo inhibition.