Electrophysiological evidence of automatic early semantic processing

This study investigates the automatic-controlled nature of early semantic processing by means of the Recognition Potential (RP), an event-related potential response that reflects lexical selection processes. For this purpose tasks differing in their processing requirements were used. Half of the participants performed a physical task involving a lower-upper case discrimination judgement (shallow processing requirements), whereas the other half carried out a semantic task, consisting in detecting animal names (deep processing requirements). Stimuli were identical in the two tasks. Reaction time measures revealed that the physical task was easier to perform than the semantic task. However, RP effects elicited by the physical and semantic tasks did not differ in either latency, amplitude, or topographic distribution. Thus, the results from the present study suggest that early semantic processing is automatically triggered whenever a linguistic stimulus enters the language processor.     

Dissociation of event-related potentials indexing arousal and semantic cohesion during emotional word encoding

Event-related potential (ERP) studies have shown that emotional stimuli elicit greater amplitude late positive-polarity potentials (LPPs) than neutral stimuli. This effect has been attributed to arousal, but emotional stimuli are also more semantically coherent than uncategorized neutral stimuli. ERPs were recorded during encoding of positive, negative, uncategorized neutral, and categorized neutral words. Differences in LPP amplitude elicited by emotional versus uncategorized neutral stimuli were evident from 450 to 1000 ms. From 450 to 700 ms, LPP effects at midline and right hemisphere frontal electrodes indexed arousal, whereas LPP effects at left hemisphere centro-parietal electrodes indexed semantic cohesion. This dissociation helps specify the processes underlying emotional stimulus encoding, and suggests the need to control for semantic cohesion in emotional information processing studies.     

Brain potentials elicited by prose-embedded linguistic anomalies

Linguistic theories distinguish between syntax (sentence form) and semantics (sentence meaning). Correspondingly, recent studies have shown that syntactic and semantic anomalies elicit distinct changes in the event-related brain potential (ERP). However, these results have been obtained with highly artificial methodologies and have not yet been generalized to more natural reading conditions. Here, we recorded ERPs while subjects read a naturalistic prose passage. The subjects either read for comprehension with no other task being assigned or read for comprehension and made acceptability judgments after each sentence. Consistent with prior work and regardless of the subjects' assigned task, syntactic anomalies elicited a large positive wave (P600), whereas semantic anomalies elicited a large increase in N400 amplitude. These results demonstrate that the qualitatively distinct ERP responses elicited by syntactic and semantic anomalies are not artifacts of unnatural aspects of previously used stimuli, thereby providing additional evidence that separable syntactic and semantic processes exist.     

Context effects in stroop-like word and picture processing

Presents a series of 6 experiments in which Stroop-like effects were generated by modally pure color-color, picture-picture, and word-word stimuli instead of the usual modally mixed color-word or picture-word stimuli. Naming, reading, and categorization tasks were applied. The Stroop inhibition was preserved with these stimuli but unexpectedly showed a semantic gradient only in the naming and not in the reading task. Word categorizing was slower and more interference prone than picture categorizing. These and other results can be captured by a model with two main assumptions: (a) semantic memory and the lexicon are separate, and (b) words have privileged access to the lexicon, whereas pictures and colors have privileged access to the semantic network. Such a model is developed and put to an initial test.     

The effects of print exposure on sentence processing and memory in older adults: Evidence for efficiency and reserve

The present study was an examination of how exposure to print affects sentence processing and memory in older readers. A sample of older adults (N = 139; Mean age = 72) completed a battery of cognitive and linguistic tests and read a series of sentences for recall. Word-by-word reading times were recorded and generalized linear mixed effects models were used to estimate components representing attentional allocation to word-level and textbase-level processes. Older adults with higher levels of print exposure showed greater efficiency in word-level processing and in the immediate instantiation of new concepts, but allocated more time to semantic integration at clause boundaries. While lower levels of working memory were associated with smaller wrap-up effects, individuals with higher levels of print exposure showed a reduced effect of working memory on sentence wrap-up. Importantly, print exposure was not only positively associated with sentence memory, but was also found to buffer the effects of working memory on sentence recall. These findings suggest that the increased efficiency of component reading processes that come with life-long habits of literacy buffer the effects of working memory decline on comprehension and contribute to maintaining skilled reading among older adults.     

The N400 and the fourth grade shift

While behavioral and educational data characterize a fourth grade shift in reading development, neuroscience evidence is relatively lacking. We used the N400 component of the event‐related potential waveform to investigate the development of single word processing across the upper elementary years, in comparison to adult readers. We presented third graders, fourth graders, fifth graders, and college students with a well‐controlled list of real words, pseudowords, letter strings, false font strings, and animal name targets. Words and pseudowords elicited similar N400s across groups. False font strings elicited N400s similar to words and letter strings in the three groups of children, but not in college students. The pattern of findings suggests relatively adult‐like semantic and phonological processing by third grade, but a long developmental time course, beyond fifth grade, for orthographic processing in this context. Thus, the amplitude of the N400 elicited by various word‐like stimuli does not reflect some sort of shift or discontinuity in word processing around the fourth grade. However, the results do suggest different developmental time courses for the processes that contribute to automatic single word reading and the integrative N400.     

Processing relative clauses varying on syntactic and semantic dimensions: An analysis with event-related potentials

Event-related potentials were used to study how parsing of German relative clauses is influenced by semantic information. Subjects read well-formed sentences containing either a subject or an object relative clause and answered questions concerning the thematic roles expressed in those sentences. Half of the sentences contained past participles that on grounds of semantic plausibility biased either a subject or an object relative reading; the other half contained past participles that provided no semantic information favoring either reading. The past participle elicited an N400 component, larger in amplitude for neutral than for semantically biased verbs, but this occurred only in the case of subject relative clauses. More specific effects were obtained only for a subgroup of subjects, when these were grouped into fast and slow comprehenders on the basis of their questionanswering reaction times. Fast comprehenders showed larger N400 amplitudes for neutral than for semantically biased past participles in general and larger N400s for the latter when there was a bias for an object relative reading as opposed to a subject relative reading. Syntactic ambiguity resolution, indicated by an auxiliary in sentence final position, was associated in this subgroup with a positive component (P345), larger in amplitude for auxiliaries indicating an object relative reading than for those indicating a subject relative reading. The latter component was independent of semantically biasing information given by a preceding past participle. Implications of these findings for models of language comprehension are considered.     

Comparison of brain mechanisms underlying the processing of Chinese characters and pseudo-characters: an event-related potential study

Most Chinese characters are composed of a semantic radical on the left and a phonetic radical on the right. The semantic radical provides the semantic information; the phonetic radical provides information concerning the pronunciation of the whole character. The pseudo‐characters in the study consisted of different sub‐lexical parts of real Chinese characters and consequently they also had the semantic radical and the phonetic radical. But they were not readable and had no actual meaning. In order to investigate the spatiotemporal cortical activation patterns underlying the orthographic, phonological and semantic processing of Chinese characters, we used event‐related brain potentials (ERPs) to explore the processing of Chinese characters and pseudo‐characters when 14 healthy Chinese college students viewed the characters passively. Results showed that both Chinese characters and pseudo‐characters elicited an evident negative potential peaking around 120 ms (N120), which appeared to reflect initial orthographic distinction and evaluation. Then, Chinese pseudo‐characters elicited a more positive ERP deflection (P220) than did Chinese characters 200–250 ms after onset of the stimuli. It was similar to the recognition potential (RP) and might reflect the integration processes of phonological and semantic processing on the basis of early orthographic information. Dipole source analysis of the difference wave (pseudo‐characters minus characters) indicated that a generator localized in the left temporal‐occipital junction contributed to this effect, which was possibly related to phonological and perceptual–semantic information integration. Between 350–450 ms, a greater negativity (N360) in pseudo‐characters as compared to characters was found over midline fronto‐central scalp regions. Dipole analysis localized the generator of N360 in the right parahippocampal cortex. Therefore, the N360 might be an N400 component and reflect the higher‐level semantic activation on the basis of orthographic, phonological and perceptual–semantic processing.     

识别电位认知功能探析

识别电位(Recognition Potential, RP)是被试看到可识别视觉刺激时, 在200~250ms内达到峰值的脑电反应。识别电位的研究正处于理论探讨阶段, 有两种主要观点用于解释RP。一种观点强调RP反映了视知觉分析成分; 另一种观点强调RP反映了语义或概念加工成分。两种观点至今未达成一致。最近, 针对两种观点质疑, 研究者们提出了类别特征加工的观点, 这一新观点在理论上符合大脑经济性的原则, 具有一定的优越性, 但尚需要更多的实证研究的支持。未来的RP研究应从实验材料的多样化、多研究方法结合、类别特征加工能力的习得机制等方面展开。     

On the interaction between linguistic and pictorial systems in the absence of semantic mediation: Evidence from a priming paradigm

Use of the letter search task in the context of the priming paradigm has proved to be an invaluable tool for the investigation of the strategic control of processes involved in word recognition. In particular, previous findings that letter search on a prime word interferes with the priming of semantically/associatively related targets, but not with the priming of either identical or morphologically related targets, suggests that letter search may selectively interfere with semantic processing, leaving other levels of processing intact. In the present experiments, this investigation was extended by exploring the priming of pictures following letter search of either a same-concept word (repetition priming) or a semantically/associatively related word (semantic priming). There was significant repetition priming of picture categorization following both silent reading and letter search of the prime word (Experiments 1 and 2). In contrast, semantic priming of pictures was found only following silent reading of the prime; there was no semantic priming following letter search of the prime (Experiment 2). This pattern of results suggests that focusing attention at the letter level during prime processing selectively attenuates activation of the semantic system by the prime. It does not prevent the spread of activation between the lexical and pictogen levels of representation of a given concept.     

Detection of sound rise time by adults with dyslexia

Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.     

Vivid: How valence and arousal influence word processing under different task demands

In this study, we used event-related potentials to examine how different dimensions of emotion—valence and arousal—influence different stages of word processing under different task demands. In two experiments, two groups of participants viewed the same single emotional and neutral words while carrying out different tasks. In both experiments, valence (pleasant, unpleasant, and neutral) was fully crossed with arousal (high and low). We found that the task made a substantial contribution to how valence and arousal modulated the late positive complex (LPC), which is thought to reflect sustained evaluative processing (particularly of emotional stimuli). When participants performed a semantic categorization task in which emotion was not directly relevant to task performance, the LPC showed a larger amplitude for high-arousal than for low-arousal words, but no effect of valence. In contrast, when participants performed an overt valence categorization task, the LPC showed a large effect of valence (with unpleasant words eliciting the largest positivity), but no effect of arousal. These data show not only that valence and arousal act independently to influence word processing, but that their relative contributions to prolonged evaluative neural processes are strongly influenced by the situational demands (and by individual differences, as revealed in a subsequent analysis of subjective judgments).     

Priming and stimulus-response learning in perceptual classification tasks

Participants often respond more quickly and more accurately to a repeated stimulus compared to a non-repeated one, a phenomenon known as repetition priming. In semantic classification tasks priming appears to be largely attributable to the learning of stimulus-decision and stimulus-response associations, which allow participants to bypass many of the processes engaged during initial stimulus analysis. The current study tested whether stimulus-response learning plays a similarly dominant role in priming that occurs in perceptual classification tasks. Unfamiliar objects were used as stimuli to reduce the influence of semantic processes on priming and the task switched for all test trials to eliminate stimulus-decision learning. The results showed across-task priming as measured by reaction time facilitation and improved accuracy when the response remained the same during the encoding and test phases. When the response switched, similar levels of reaction time facilitation were observed, but priming as measured by accuracy was significantly reduced and no longer significant. These findings indicate that stimulus-response learning contributes to priming in perceptual classification tasks, but does not play a dominant role. Significant stimulus-level learning that is independent of the task and response also occurs and likely indexes facilitated perceptual processing of the objects.     

再探汉字加工中语音、语义激活的相对时间进程

在Zhou和Marslen-Wilson（2000）基础之上,进一步探讨汉字加工中语音和语义信息激活的相对时间进程及其对汉字加工理论的含义。采用启动范式,用同一目标字与语义相关启动字、同音启动字以及无关控制启动字配对,变化同音启动字读音与其声旁的规则性,变化启动字与目标字呈现之间的时间间隔（SOA,57ms或200ms）,使用两种实验任务（真假字判断和命名）,考察语义、语音效应发生的时间先后与效应量的大小。真假字判断实验发现,不管SOA如何,语义启动效应都非常显著,而同音启动效应则随SOA的增长而逐渐加大,从不显著到显著;同音启动字读音规则性对启动效应没有明显影响。命名实验发现,语义启动、同音启动效应同时存在于长、短SOA条件中。长SOA时,两者在数值上没有显著差异;短SOA时,同音不规则字产生的启动效应等同于语义启动效应,而同音规则字产生的启动效应则大于语义启动效应。结合其它实验发现,这些结果说明,在熟练的汉字加工中,语音信息的激活并不比语义信息早,语音激活也不是语义激活的先决条件;但汉字各种信息激活的相对激活量和时间进程会随任务性质和材料性质而在一定范围内有所改变。     

阈下知觉的加工水平及其发生条件—— 基于视觉掩蔽启动范式的视角

Dehaene等(1998)和Greenwald等(1996)的研究通过在方法上的完善, 为阈下知觉的存在提供了确凿的证据。但是阈下知觉可以达到什么样的深度这一问题尚仍然存在争议, 有研究者认为阈下知觉可以达到语义加工的水平, 而有的研究者认为阈下知觉只是对刺激视觉特征的一种浅层加工, 并形成了一些非语义加工的假说。在以往研究的基础上, 本研究通过完善实验范式, 分别采用图片、字词作为实验材料对阈下知觉的深度和影响因素进行探讨。实验1和实验2立据于阈下非语义加工的各种理论, 为阈下语义加工的存在提供了证据。同时实验2表明, 阈下知觉达到的水平取决于靶子集的大小, 更确切的说取决于被试对靶刺激进行了何种水平的加工。     

ERPs and contextual semantic discrimination: degrees of congruence in wakefulness and sleep

This study explores whether the brain can discriminate degrees of semantic congruency during wakefulness and sleep. Experiment 1 was conducted during wakefulness to test degrees of congruency by means of N400 amplitude. In Experiment 2, the same paradigm was applied to a different group of participants during natural night sleep. Stimuli were 108 sentences (definitions with two attributes) with four possible degrees of congruence as ending targets. In both studies, the amplitude of N400-like effect showed modulation according to the degree of congruency. The results indicate that the brain can accomplish sentential semantic discriminations not only in wakefulness but also in sleep.     

The semantic component of the evoked potential of differentiation

This work analyzes data from recordings of (occipital and temporal) cortical evoked potentials (called evoked potentials of differentiation (EPD) occurring in humans in response to an abrupt substitution of stimuli. As stimuli we used three groups of words: the names of the ten basic colors taken from Newton's color circle; the names of seven basic emotions forming Shlossberg's circle of emotions; and seven nonsense words comprised of random combinations of letters. Within each group of word stimuli we constructed a matrix of the differences between the amplitudes of mid-latency components of EPD for each pair of words. This matrix was analyzed using the method of multidimensional scaling. As a result of this analysis we were able to distinguish the semantic and configurational components of EPD amplitude. The semantic component of EPD amplitude was evaluated by comparing structure of the data obtained to the circular structures of emotion and color names. The configurational component was evaluated on the basis of the attribute of word length (number of letters). It was demonstrated that the semantic component of the EPD can only be detected in the left occipital lead at an interpeak amplitude of P120-N180. The configurational component is reflected in the occipital and temporal leads to an identical extent, but only in the amplitude of a later (N180-P230) component of the EPD. The results obtained are discussed in terms of the coding of categorized, configurational, and semantic attributes of a visual stimulus.     

Semantic, phonological, and mediated priming in reading and lexical decisions

Four experiments were conducted to investigate whether semantic activation of a concept spreads to phonologically and graphemically related concepts. In lexical decision or self-paced reading tasks, subjects responded to pairs of words that were semantically related (e.g., light-lamp), that rhymed (e.g., lamp-damp), or that combined both of these relations through a mediating word (e.g., light-damp). In one version of each task, test lists contained word-word pairs (e.g., light-lamp) as well as nonword-word (e.g., pown-table) and word-nonword pairs (e.g., month-poad); in another version, test lists contained only word-word pairs. The lexical decision and self-paced reading tasks were facilitated by semantic and rhyming relations regardless of the presence or absence of nonwords on the test lists. The effect of the mediated relation, however, depended on the presence of nonwords among the stimuli. When only words were included, there was no effect of the mediated relation, but when nonwords were included, lexical decision and self-paced reading responses were inhibited by the mediated relation. These inhibitory effects are attributed to processes occurring after lexical access, and the relative advantages of the self-paced reading task are discussed.     

Tell me sweet little lies: An event-related potentials study on the processing of social lies

In reading tasks, words that convey a false statement elicit an enhanced N400 brainwave response, relative to words that convey a true statement. N400 amplitude reductions are generally linked to the online expectancy of upcoming words in discourse. White lies, contrary to false statements, may not be unexpected in social scenarios. We used the event-related potential (ERP) technique to determine whether there is an impact of social context on sentence processing. We measured ERP responses to target words that either conveyed a social “white” lie or a socially impolite blunt truth, relative to semantic violations. Word expectancy was controlled for by equating the cloze probabilities of white lying and blunt true targets, as measured in previous paper-and-pencil tests. We obtained a classic semantic violation effect (a larger N400 for semantic incongruities relative to sense making statements). White lies, in contrast to false statements, did not enhance the amplitude of the N400 component. Interestingly, blunt true statements yielded both a late frontal positivity and an N400 response in those scenarios particularly biased to white lying. Thus, white lies do not interfere with online semantic processing, and they do not engage further reanalysis processes, which are typically indexed by subsequent late positivity ERP effects. Instead, an N400 and a late frontal positivity obtained in response to blunt true statements indicate that they were treated as unexpected events. In conclusion, unwritten rules of social communicative behavior influence the electrical brain response to locally coherent but socially inappropriate statements.