Acquired affective associations induce emotion effects in word recognition: An ERP study

The present study examined how contextual learning and in particular emotionality conditioning impacts the neural processing of words, as possible key factors for the acquisition of words’ emotional connotation. 21 participants learned on five consecutive days associations between meaningless pseudowords and unpleasant or neutral pictures using an evaluative conditioning paradigm. Subsequently, event-related potentials were recorded while participants implicitly processed the learned emotional relevance in a lexical decision paradigm. Emotional and neutral words were presented together with the conditioned pseudowords and a set of new pseudowords. Conditioned and new pseudowords differed in the late positive complex. Emotionally and neutrally conditioned stimuli differed in an early time window (80–120 ms) and in the P300. These results replicate ERP effects known from emotion word recognition and indicate that contextual learning and in particular evaluative conditioning is suitable to establish emotional associations in words, and to explain early ERP effects in emotion word recognition.     

Event-related potentials of emotional memory: encoding pleasant,unpleasant, and neutral pictures

Emotional events tend to be remembered better than nonemotional events. We investigated this phenomenon by measuring two event-related potential (ERP) effects: the emotion effect (more positive ERPs for pleasant or unpleasant stimuli than for neutral stimuli) and the subsequent memory effect (more positive ERPs for subsequently remembered items than for subsequently forgotten items). ERPs were measured while subjects rated the emotional content of pleasant, unpleasant, and neutral pictures. As was expected, subsequent recall was better for pleasant and unpleasant pictures than for neutral pictures. The emotion effect was sensitive to arousal in parietal electrodes and to both arousal and valence in frontocentral electrodes. The subsequent memory effect at centroparietal electrodes was greater for emotional pictures than for neutral pictures during an early epoch (400-600 msec). This result suggests that emotional information has privileged access to processing resources, possibly leading to better memory formation.     

Written threat: Electrophysiological evidence for an attention bias to affective words in social anxiety disorder

Social anxiety disorder (SAD) is associated with heightened sensitivity to threat cues, typically represented by emotional facial expressions. To examine if this bias can be transferred to a general hypersensitivity or whether it is specific to disorder relevant cues, we investigated electrophysiological correlates of emotional word processing (alpha activity and event-related potentials) in 20 healthy participants and 20 participants with SAD. The experimental task was a silent reading of neutral, positive, physically threatening and socially threatening words (the latter were abusive swear words) while responding to a randomly presented dot. Subsequently, all participants were asked to recall as many words as possible during an unexpected recall test. Participants with SAD showed blunted sensory processing followed by a rapid processing of emotional words during early stages (early posterior negativity – EPN). At later stages, all participants showed enhanced processing of negative (physically and socially threatening) compared to neutral and positive words (N400). Moreover, at later processing stages alpha activity was increased specifically for negative words in participants with SAD but not in healthy controls. Recall of emotional words for all subjects was best for socially threatening words, followed by negative and positive words irrespective of social anxiety. The present findings indicate that SAD is associated with abnormalities in emotional word processing characterised by early hypervigilance to emotional cues followed by cognitive avoidance at later processing stages. Most importantly, the specificity of these attentional biases seems to change as a function of time with a general emotional bias at early and a more specific bias at later processing stages.     

Electrophysiological differences in the processing of affective information in words and pictures

It is generally assumed that affective picture viewing is related to higher levels of physiological arousal than is the reading of emotional words. However, this assertion is based mainly on studies in which the processing of either words or pictures has been investigated under heterogenic conditions. Positive, negative, relaxing, neutral, and background (stimulus fragments) words and pictures were presented to subjects in two experiments under equivalent experimental conditions. In Experiment 1, neutral words elicited an enhanced late positive component (LPC) that was associated with an increased difficulty in discriminating neutral from background stimuli. In Experiment 2, high-arousing pictures elicited an enhanced early negativity and LPC that were related to a facilitated processing for these stimuli. Thus, it seems that under some circumstances, the processing of affective information captures attention only with more biologically relevant stimuli. Also, these data might be better interpreted on the basis of those models that postulate a different access to affective information for words and pictures.     

Effects of emotional content on working memory capacity

Emotional events tend to be remembered better than neutral events, but emotional states and stimuli may also interfere with cognitive processes that underlie memory performance. The current study investigated the effects of emotional content on working memory capacity (WMC), which involves both short term storage and executive attention control. We tested competing hypotheses in a preregistered experiment (N?=?297). The emotional enhancement hypothesis predicts that emotional stimuli attract attention and additional processing resources relative to neutral stimuli, thereby making it easier to encode and store emotional information in WMC. The emotional impairment hypothesis, by contrast, predicts that emotional stimuli interfere with attention control and the active maintenance of information in working memory. Participants completed a common measure of WMC (the operation span task; Turner, M. L., &; Engle, R. W. [1989]. Is working memory capacity task dependent? Journal of Memory and Language, 28, 127–154) that included either emotional or neutral words. Results revealed that WMC was reduced for emotional words relative to neutral words, consistent with the emotional impairment hypothesis.     

Emotional scenes elicit more pronounced self-reported emotional experience and greater EPN and LPP modulation when compared to emotional faces

Emotional faces and scenes carry a wealth of overlapping and distinct perceptual information. Despite widespread use in the investigation of emotional perception, expressive face and evocative scene stimuli are rarely assessed in the same experiment. Here, we evaluated self-reports of arousal and pleasantness, as well as early and late event-related potentials (e.g., N170, early posterior negativity [EPN], late positive potential [LPP]) as subjects viewed neutral and emotional faces and scenes, including contents representing anger, fear, and joy. Results demonstrate that emotional scenes were rated as more evocative than emotional faces, as only scenes produced elevated self-reports of arousal. In addition, viewing scenes resulted in more extreme ratings of pleasantness (and unpleasantness) than did faces. EEG results indicate that both expressive faces and emotional scenes evoke enhanced negativity in the N170 component, while the EPN and LPP components show significantly enhanced modulation only by scene, relative to face stimuli. These data suggest that viewing emotional scenes results in a more pronounced emotional experience that is associated with reliable modulation of visual event-related potentials that are implicated in emotional circuits in the brain.     

The facilitated processing of threatening faces: an ERP analysis

Threatening, friendly, and neutral faces were presented to test the hypothesis of the facilitated perceptual processing of threatening faces. Dense sensor event-related brain potentials were measured while subjects viewed facial stimuli. Subjects had no explicit task for emotional categorization of the faces. Assessing early perceptual stimulus processing, threatening faces elicited an early posterior negativity compared with nonthreatening neutral or friendly expressions. Moreover, at later stages of stimulus processing, facial threat also elicited augmented late positive potentials relative to the other facial expressions, indicating the more elaborate perceptual analysis of these stimuli. Taken together, these data demonstrate the facilitated perceptual processing of threatening faces. Results are discussed within the context of an evolved module of fear (A. Ohman & S. Mineka, 2001).     

情绪效价的记忆增强效应:存储或提取优势?

情绪效价和情绪唤醒是描述情绪的两个维度。情绪增强记忆效应表明情绪唤醒事件的记忆往往优于非情绪唤醒事件的记忆,但关于积极情绪记忆和消极情绪记忆哪个在记忆中处于优势仍存在争论。实验以情绪词对和中性词对为实验材料。实验一探讨积极情绪词语或消极情绪词语的记忆优势; 实验二探讨积极情绪环境或消极情绪环境中中性词语的记忆优势。在两种实验条件下,积极情绪下的自由回忆都优于消极情绪下的自由回忆; 多项加工树的存储—提取模型使用实验自由回忆和线索回忆的结果将记忆的存储和提取优势分离开来,结果表明:积极情绪事件记忆优势发生在存储阶段,而积极情绪环境记忆优势发生在存储和提取阶段; 积极情绪事件记忆偏向支持“刺激后编码增强假设”,积极情绪环境记忆偏向支持“唤醒—偏向竞争假设”。     

Electrophysiological indices of emotion processing during retrieval of autobiographical memories by school-age children

We used event-related potentials (ERPs) to examine emotion processing during retrieval of emotional autobiographical memories by school-age children. We initiated processing of the emotional experiences using neutral cue words. On one-third of trials, children were instructed to think of a memory of a negative event, and on another third of trials, they were instructed to think of a memory of a positive event. We then recorded ERPs from 32 electrode sites as the children processed the emotional memories again later in the testing session. The 7- to 10-year-old children generated memories appropriate to the valences specified in the instructions. Neural responses differed as a function of the emotional valence of the events associated with the cues and as a function of gender. In the sample as a whole, differential processing of positive relative to negative and neutral emotions was apparent at posterior electrode sites 1,000–1,500 ms after stimulus onset. For girls, the effect was apparent beginning at 500 ms. No differences between the neural responses to negative and neutral stimuli were observed. At frontal electrode sites, girls evidenced faster processing of positive than of negative emotion, whereas boys evidenced faster processing of negative than of positive emotion. In conclusion, we discuss the possible origins of gender-differential patterns of neural processing.     

Limb-specific emotional modulation of cervical spinal cord neurons

Emotional stimuli receive prioritized attentional and motoric processing in the brain. Recent data have indicated that emotional stimuli enhance activity in the cervical spinal cord as well. In the present study, we used fMRI to investigate the specificity of this emotion-dependent spinal cord activity. We examined whether the limb depicted in a passively viewed image (upper vs. lower) differentially influenced activity in the cervical segments that innervate the upper limbs, and whether this effect was enhanced by emotion. Participants completed four fMRI runs: neutral–upper limb, neutral–lower limb, negative–upper limb, and negative–lower limb. The results indicated main effects of limb and emotion, with upper limbs and negative stimuli eliciting greater activity than lower limbs and neutral stimuli, respectively. For upper-limb runs, negative stimuli evoked more activity than did neutral stimuli. Additionally, negative stimuli depicting upper limbs produced stronger responses than did negative stimuli depicting lower limbs. These results suggest that emotional stimuli augment limb-specific responses in the spinal cord.     

儿童与成人对社会和非社会正性情绪刺激脑电反应特征比较

采用事件相关电位技术探究不同年龄群体社会与非社会正性情绪刺激加工是否具有差异。研究发现：在P2成分上,成人在情绪刺激下诱发的波幅大于儿童;N2成分上,儿童在三种情绪刺激条件下波幅无显著差异。成人在社会性情绪刺激条件下诱发的脑电波幅大于在中性情绪刺激条件和非社会情绪刺激条件下诱发波幅;在LPP早、中、晚时间窗中,儿童的LPP波幅大于成人。由此,儿童与成人在社会和非社会正性情绪刺激加工上存在明显差异。     

Brain mechanisms involved in angry prosody change detection in school-age children and adults,revealed by electrophysiology

Voices transmit social signals through speech and/or prosody. Emotional prosody conveys key information about the emotional state of a speaker and is thus a crucial cue that one has to detect in order to develop efficient social communication. Previous studies in adults reported different brain responses to emotional than to neutral prosodic deviancy. The aim of this study was to characterize such specific emotional deviancy effects in school-age children. The mismatch negativity (MMN) and P3a evoked potentials, reflecting automatic change detection and automatic attention orienting, respectively, were obtained for neutral and emotional angry deviants in both school-age children (n = 26) and adults (n = 14). Shorter latencies were found for emotional than for neutral preattentional responses in both groups. However, whereas this effect was observed on the MMN in adults, it appeared in an early discriminative negativity preceding the MMN in children. A smaller P3a amplitude was observed for the emotional than for the neutral deviants at all ages. Overall, the brain responses involved in specific emotional change processing are already present during childhood, but responses have not yet reached an adult pattern. We suggest that these processing differences might contribute to the known improvement of emotional prosody perception between childhood and adulthood.     

Time course and task dependence of emotion effects in word processing

The emotional content of stimuli influences cognitive performance. In two experiments, we investigated the time course and mechanisms of emotional influences on visual word processing in various tasks by recording event-related brain potentials (ERPs). The stimuli were verbs of positive, negative, and neutral valence. In Experiment 1, where lexical decisions had to be performed on single verbs, both positive and negative verbs were processed more quickly than neutral verbs and elicited a distinct ERP component, starting around 370 msec. In Experiment 2, the verbs were embedded in a semantic context provided by single nouns. Likewise, structural, lexical, and semantic decisions for positive verbs were accelerated, and an ERP effect with a scalp distribution comparable to that in Experiment 1 now started about 200 msec earlier. These effects may signal an automatic allocation of attentional resources to emotionally arousing words, since they were not modulated by different task demands. In contrast, a later ERP effect of emotion was restricted to lexical and semantic decisions and, thus, appears to indicate more elaborated, task-dependent processing of emotional words.     

Emotional memory for words: Separating content and context

We developed a technique to examine the effects of emotional content and context on verbal memory. Two sets of sentences were devised: in the first, each sentence was emotionally arousing due to the inclusion of an emotional “target” word. In the second set, “targets” were replaced with well-matched neutral words. Subjects read aloud a selection of emotional and neutral sentences, and were then surprised with memory tasks after a range of time delays. Emotional target words were remembered significantly better than neutral words in all experiments. Recognition of emotional words was relatively stable despite increasing delays between encoding and recognition testing, in contrast to memory for neutral words, which decayed over time. Memory for neutral non-target words was enhanced when words had been presented in an emotional context. The results confirm the phenomenon of emotional enhancement of memory at short and long delays and suggest that emotional context may be encoded independently of word meaning.     

神经重用假说的汉语情绪词汇加工证据

神经重用假说认为对词的情绪效应可以不经语义形成而先行产生, 这更有助于人类适应环境。为了检验这一假说, 设计脑电实验和行为实验, 记录被试加工汉语厌恶情绪词和中性词的特征。结果发现, 170 ms左右厌恶词与中性词的ERPs发生分离, 且在枕部出现情绪刺激视觉注意关联的EPN; 厌恶词与中性词N400差异波溯源定位于脑岛附近, 其最大激活点时间窗口开始于380 ms。这表明在情绪词汇的语义分析之前就出现了情绪效应, 结果支持了神经重用假说。     

情绪词对新异刺激喜好度变化的调节机制

通过三个实验探讨了情绪词的情绪信息对新异刺激喜好度变化的调节机制。实验采用评价条件化(Evaluative Conditioning)范式, 将新异刺激(相当于条件刺激, CS)与情绪词(相当于无条件刺激, US)配对呈现, 最后测量被试对新异刺激的喜好程度。三个实验通过设置表面故事, 控制新异刺激与情绪词间的配对关系, 并改变任务的加工深度, 揭示了情绪词调节新异刺激喜好度变化的机制。研究结果表明, 情绪词对新异刺激喜好度的调节不依赖于对刺激间偶联关系的意识以及被试的任务状态, 是一种自下而上的自动化的联想学习过程。     

Reduced memory for the spatial and temporal context of unpleasant words

Emotional stimuli are consistently better remembered than neutral stimuli. However, the reported effects of emotional stimuli on source memory are less consistent. In four experiments, we examined spatial and temporal source memory and free recall for emotional words previously studied in an fMRI experiment. In the fMRI experiment, the unpleasant but not the pleasant words were shown to activate the amygdala. In the experiments reported here, spatial and temporal source memory were reduced for the unpleasant words compared to pleasant and neutral words. Reduced spatial memory for unpleasant words was observed across studies that varied the specific stimuli, task conditions, and incidental versus intentional encoding instructions. Free recall was enhanced for the pleasant and unpleasant words compared to neutral words. The results demonstrate reduced source memory for unpleasant words even when item recall is enhanced. Our findings are consistent with prior reports of amygdala-mediated amnestic effects evoked by unpleasant stimuli.     

Friendly drug-dealers and terrifying puppies: Affective primacy can attenuate the N400 effect in emotional discourse contexts

Words that are semantically congruous with their preceding discourse context are easier to process than words that are semantically incongruous with their context. This facilitation of semantic processing is reflected by an attenuation of the N400 event-related potential (ERP). We asked whether this was true of emotional words in emotional contexts where discourse congruity was conferred through emotional valence. ERPs were measured as 24 participants read two-sentence scenarios with critical words that varied by emotion (pleasant, unpleasant, or neutral) and congruity (congruous or incongruous). Semantic predictability, constraint, and plausibility were comparable across the neutral and emotional scenarios. As expected, the N400 was smaller to neutral words that were semantically congruous (vs. incongruous) with their neutral discourse context. No such N400 congruity effect was observed on emotional words following emotional discourse contexts. Rather, the amplitude of the N400 was small to all emotional words (pleasant and unpleasant), regardless of whether their emotional valence was congruous with the valence of their emotional discourse context. However, consistent with previous studies, the emotional words produced a larger late positivity than did the neutral words. These data suggest that comprehenders bypassed deep semantic processing of valence-incongruous emotional words within the N400 time window, moving rapidly on to evaluate the words’ motivational significance.     

Auditory emotional cues enhance visual perception

Recent studies show that emotional stimuli impair performance to subsequently presented neutral stimuli. Here we show a cross-modal perceptual enhancement caused by emotional cues. Auditory cue words were followed by a visually presented neutral target word. Two-alternative forced-choice identification of the visual target was improved by emotional cues as compared to neutral cues. When the cue was presented visually we replicated the emotion-induced impairment found in other studies. Our results suggest emotional stimuli have a twofold effect on perception. They impair perception by reflexively attracting attention at the expense of competing stimuli. However, emotional stimuli also induce a nonspecific perceptual enhancement that carries over onto other stimuli when competition is reduced, for example, by presenting stimuli in different modalities.     

Fearful expressions enhance recognition memory: electrophysiological evidence

Facial expressions play a key role in affective and social behavior. However, the temporal dynamics of the brain responses to emotional faces remain still unclear, in particular an open question is at what stage of face processing expressions might influence encoding and recognition memory. To try and answer this question we recorded the event-related potentials (ERPs) elicited in an old/new recognition task. A novel aspect of the present design was that whereas faces were presented during the study phase with either a happy, fearful or neutral expression, they were always neutral during the memory retrieval task. The ERP results showed three main findings: An enhanced early fronto-central positivity for faces encoded as fearful, both during the study and the retrieval phase. During encoding subsequent memory (Dm effect) was influenced by emotion. At retrieval the early components P100 and N170 were modulated by the emotional expression of the face at the encoding phase. Finally, the later ERP components related to recognition memory were modulated by the previously encoded facial expressions. Overall, these results suggest that face recognition is modulated by top-down influences from brain areas associated with emotional memory, enhancing encoding and retrieval in particular for fearful emotional expressions.