Sublexical ambiguity effect in reading Chinese disyllabic compounds

For Chinese compounds, neighbors can share either both orthographic forms and meanings, or orthographic forms only. In this study, central presentation and visual half-field (VF) presentation methods were used in conjunction with ERP measures to investigate how readers solve the sublexical semantic ambiguity of the first constituent character in reading a disyllabic compound. The sublexical ambiguity of the first character was manipulated while the orthographic neighborhood sizes of the first and second character (NS1, NS2) were controlled. Subjective rating of number of meanings corresponding to a character was used as an index of sublexical ambiguity. Results showed that low sublexical ambiguity words elicited a more negative N400 than high sublexical ambiguity words when words were centrally presented. Similar patterns were found when words were presented to the left VF. Interestingly, different patterns were observed for pseudowords. With left VF presentation, high sublexical ambiguity psudowords showed a more negative N400 than low sublexical ambiguity pseudowords. In contrast, with right VF presentation, low sublexical ambiguity pseudowords showed a more negative N400 than high sublexical ambiguity pseudowords. These findings indicate that a level of morphological representation between form and meaning needs to be established and refined in Chinese. In addition, hemispheric asymmetries in the use of word information in ambiguity resolution should be taken into account, even at sublexical level.     

句子语境中汉语词汇歧义消解的ERP研究

采用ERP方法,考察了汉语词汇歧义消解中句子语境作用的时间进程及大脑活动。目标词与句子语境存在一致、不一致、无关控制等3种关系。结果显示:(1)一致与不一致条件下N400的平均波幅均显著低于无关控制条件;(2)SOA为200毫秒时产生的N400平均波幅的幅度显著高于SOA为1000毫秒的条件;(3)N400的平均波幅及潜伏期均表现出左半球显著高于右半球的特点。实验结果支持词汇歧义消解的模块化观点,体现了大脑两半球语言功能的不对称性。     

Font effects of Chinese characters and pseudo-characters on the N400: evidence for an orthographic processing view

Event-related brain potentials (ERPs) were recorded during a Chinese character decision task to examine whether N400 amplitude is modulated by stimulus font. Results revealed large negative-going ERPs in an N400 time window of 300-500ms to stimuli presented in degraded Xing Kai Ti (XKT) font compared with more intact Song Ti (ST) font regardless of whether the stimuli were real or pseudo-characters. ERPs for the pseudo-characters were more negative than for the real characters with similar timing and scalp distribution. The N400-like font effect on amplitude is interpreted as analogous to an N400 stimulus degradation effect, an extension to Holcomb (1993); the degraded perceptual cues provided by XKT supposedly account for this degradation effect. This effect is further interpreted to reflect relative difficulty, which results from orthographic processing difficulty, in retrieving the meaning of XKT stimuli compared with ST stimuli.     

Brain responses to lexical-semantic priming in children at-risk for dyslexia

Deviances in early event-related potential (ERP) components reflecting auditory and phonological processing are well-documented in children at familial risk for dyslexia. However, little is known about brain responses which index processing in other linguistic domains such as lexicon, semantics and syntax in this group. The present study investigated effects of lexical-semantic priming in 20- and 24-month-olds at-risk for dyslexia and typically developing controls in two ERP experiments. In both experiments an early component assumed to reflect facilitated lexical processing for primed words was enhanced in the at-risk group compared to the control group. Moreover, an N400-like response which was prominent in the control group was attenuated or absent in at-risk children. Results suggest that deficiencies in young children at-risk for dyslexia are not restricted to perceptual and lower-level phonological abilities, but also affect higher order linguistic skills such as lexical and semantic processing.     

Chinese characters elicit face-like N170 inversion effects

Recognition of both faces and Chinese characters is commonly believed to rely on configural information. While faces typically exhibit behavioral and N170 inversion effects that differ from non-face stimuli (Rossion, Joyce, Cottrell, & Tarr, 2003), the current study examined whether a similar reliance on configural processing may result in similar inversion effects for faces and Chinese characters. Participants were engaged in an orientation judgment task (Experiment 1) and a one-back identity matching task (Experiment 2). Across two experiments, the N170 was delayed and enhanced in magnitude for upside-down faces and compound Chinese characters, compared to upright stimuli. The inversion effects for these two stimulus categories were bilateral for latency and right-lateralized for amplitudes. For simple Chinese characters, only the latency inversion effects were significant. Moreover, the size of the right-hemisphere inversion effects in N170 amplitude was larger for faces than Chinese characters. These findings show the N170 inversion effects from non-face stimuli closely parallel effects seen with faces. Face-like N170 inversion effects elicited by Chinese compound characters were attributed to the difficulty of part-whole integration as well as the disrupted regularity in relational information due to inversion. Hemispheric difference in Chinese character processing is also discussed.     

语音信息对中国英语学习者语义加工的影响及其脑机制

本研究采用经典的句尾畸义词诱发N400的ERP实验范式探讨了中国英语学习者在进行英文阅读时语音的影响及其相关脑机制。实验包括两类畸义语句:1.同音畸义:句尾词有畸义,但语音和相应正常语义句尾词相同;2.非同音畸义:句尾词有畸义,且语音和相应正常语义句尾词不同。行为数据显示:在错误率上同音畸义显著地高于非同音畸义。ERP显示:无论在早期(N100)还是晚期(N400)脑电成份上,同音畸义和非同音畸义的ERP振幅都有明显差异。本研究从行为和脑电两个方面一致揭示中国英语学习者阅读英文时受到了语音的影响。     

The propositional structure of discourse in the two cerebral hemispheres

Readers construct at least two interrelated representations when they comprehend a text: (a) a representation of the explicit ideas in a text and the relations among them (i.e., a propositional representation) and (b) a representation of the context or situation to which a text refers (i.e., a discourse model). In a recent study, found evidence that readers' representations were structured according to propositional relations, but only in the left hemisphere. Both hemispheres, however, appeared to represent contextually relevant semantic information. The goal in the current study was to examine further the organization of explicit text concepts in the two hemispheres. We used an item-priming-in-recognition paradigm in combination with a lateralized visual-field manipulation. We found evidence for a propositionally structured representation in the left hemisphere, that is, priming effects that reflected the linear distance between primes and targets in the propositional structure of passages. We also found that the right hemisphere represented explicit text concepts, but we found no evidence that these concepts were organized structurally. In a second experiment, we found our item priming effects reflected the representation of text information in memory and did not reflect lexical-semantic priming at test.     

An ERP investigation of regional and foreign accent processing

This study used event-related potentials (ERPs) to examine whether we employ the same normalisation mechanisms when processing words spoken with a regional accent or foreign accent. Our results showed that the Phonological Mapping Negativity (PMN) following the onset of the final word of sentences spoken with an unfamiliar regional accent was greater than for those produced in the listener’s own accent, whilst PMN for foreign accented speech was reduced. Foreign accents also resulted in a reduction in N400 amplitude when compared to both unfamiliar regional accents and the listener’s own accent, with no significant difference found between the N400 of the regional and home accents. These results suggest that regional accent related variations are normalised at the earliest stages of spoken word recognition, requiring less top-down lexical intervention than foreign accents.     

ERP evidence for conceptual mappings and comparison processes during the comprehension of conventional and novel metaphors

Cognitive linguists suggest that understanding metaphors requires activation of conceptual mappings between the involved concepts. We tested whether mappings are indeed in use during metaphor comprehension, and what mapping means as a cognitive process with Event-Related Potentials. Participants read literal, conventional metaphorical, novel metaphorical, and anomalous target sentences preceded by primes with related or unrelated mappings. Experiment 1 used sentence-primes to activate related mappings, and Experiment 2 used simile-primes to induce comparison thinking. In the unprimed conditions of both experiments, metaphors elicited N400s more negative than the literals. In Experiment 1, related sentence-primes reduced the metaphor-literal N400 difference in conventional, but not in novel metaphors. In Experiment 2, related simile-primes reduced the metaphor-literal N400 difference in novel, but not clearly in conventional metaphors. We suggest that mapping as a process occurs in metaphors, and the ways in which it can be facilitated by comparison differ between conventional and novel metaphors.     

The effects of attention on ear advantages in dichotic listening to words and affects

This study examined the effects of attention on ear advantages using dichotic listening to words and affects, a focused-attention paradigm. We compared the mixed condition, in which attention is switched between the ears in each trial, to the blocked condition, in which attention is directed to one ear for an entire block of trials. Results showed a decreased right ear advantage for word processing only in the mixed condition and an increased left ear advantage for emotion processing in both attention conditions for hits index. The mixed condition showed smaller laterality effects than the blocked condition for words with respect to hits index, while increasing right ear predominance for intrusions. The greater percentage of intrusions in the right ear for the word task and in the mixed condition suggests that the right ear (left hemisphere) is most vulnerable to attention switching. We posit that the attention manipulation has a greater effect on word processing than on emotion processing and propose that ear advantages reflect a combination of the effects of attentional and structural constraints on lateralisation.     

Facilitation and disruption of lateralized syllable processing by unattended stimuli in the opposite visual field

The influence of lateralized unattended stimuli on the processing of attended stimuli in the opposite visual field can shed light on the nature of information that is transferred between hemispheres. On a cued bilateral task, participants tried to identify a syllable in the attended visual field, which elicits a left hemisphere (LH) advantage and different processing strategies by the two hemispheres. The same or a different syllable or a neutral stimulus appeared in the unattended field. Transmission of unattended syllable codes between hemispheres is symmetric, as revealed by equal interference for the two visual fields. The LH is more accurate than the RH in encoding unattended syllables, as indicated by facilitation in the left but not right visual field and a greater frequency of identifiable intrusions into the left than right field. However, asymmetric encoding strategies are different for attended and unattended syllables.     

The direction of hemispheric asymmetries for object categorization at different levels of abstraction depends on the task

In this study hemispheric asymmetries for categorizing objects at the basic versus subordinate level of abstraction were investigated. As predictions derived from different theoretical approaches are contradictory and experimental evidence is inconclusive in this regard, we conducted two categorization experiments, where we contrasted two experimental paradigms. In the first experiment, subjects had to verify whether a word and a laterally presented picture matched or not. In the second experiment, subjects had to identify laterally presented pictures of animals either at the basic or subordinate level by pressing a corresponding response key. Whereas the first experiment revealed an advantage of the left hemisphere (LH) for categorizing objects at the basic level and of the right hemisphere (RH) for categorizing at the subordinate level, just the opposite brain asymmetry was found in the second experiment. As the stimuli were identical in both experiments, hemispheric asymmetries seem to be strongly task dependent.     

Hemispheric differences in the effects of context on vowel perception

Listeners perceive speech sounds relative to context. Contextual influences might differ over hemispheres if different types of auditory processing are lateralized. Hemispheric differences in contextual influences on vowel perception were investigated by presenting speech targets and both speech and non-speech contexts to listeners’ right or left ears (contexts and targets either to the same or to opposite ears). Listeners performed a discrimination task. Vowel perception was influenced by acoustic properties of the context signals. The strength of this influence depended on laterality of target presentation, and on the speech/non-speech status of the context signal. We conclude that contrastive contextual influences on vowel perception are stronger when targets are processed predominately by the right hemisphere. In the left hemisphere, contrastive effects are smaller and largely restricted to speech contexts.     

Levels of processing and phonological priming in Chinese character completion tests

This study investigated the level of processing (LoP) effect in the Chinese character completion task. Stem cues, either graphemically or phonetically related to a target character, were used to generate two different kinds of perceptual tests. By giving participants either direct or indirect instructions, the character completion tests could be either an explicit or an implicit memory test. For the implicit test, LoP effects were not found between Read and Generation conditions, whereas the Physical condition did not produce priming. In addition, no priming was found when participants received graphemic cues during the test. For the explicit test, on the other hand, a standard pattern of LoP effects was found between the Physical, Read, and Generation conditions. Results are discussed in terms of the importance of lexical access for character completion tests and the role of phonology in processing Chinese characters.     

Challenging perceptual tasks require more attention: The influence of task difficulty on the N1 effect of temporal orienting

Both filter and resource models of attention suggest an influence of task difficulty on the size of early attention effects. As for temporal orienting, the idea that early effects are modulated by task difficulty has not been tested directly, so far. To fill this empirical gap, the present study used an auditory temporal-orienting task, in which two differently pitched pure tones served as targets. To manipulate perceptual difficulty, the pitch difference between the targets was either small or large. Temporal orienting enhanced the N1 component of the auditory event-related potential. This early, sensory effect tended to be larger in the more difficult condition, particularly over the frontal scalp. Notably, increasing task difficulty affected predominantly the processing of attended stimuli. Hence, temporal orienting may operate by increasing processing resources or gain settings for the attended time point – rather than by withdrawing resources from the unattended time point.     

Lateralized effects of categorical and coordinate spatial processing of component parts on the recognition of 3D non-nameable objects

Participants performed two object-matching tasks for novel, non-nameable objects consisting of geons. For each original stimulus, two transformations were applied to create comparison stimuli. In the categorical transformation, a geon connected to geon A was moved to geon B. In the coordinate transformation, a geon connected to geon A was moved to a different position on geon A. The Categorical task consisted of the original and the categorically transformed objects. The Coordinate task consisted of the original and the coordinately transformed objects. The original object was presented to the central visual field, followed by a comparison object presented to the right or left visual half-fields (RVF and LVF). The results showed an RVF advantage for the Categorical task and an LVF advantage for the Coordinate task. The possibility that categorical and coordinate spatial processing subsystems would be basic computational elements for between- and within-category object recognition was discussed.     

Gapping: Electrophysiological evidence for immediate processing of "missing" verbs in sentence comprehension

In the present study we use event related potentials (ERPs) to explore the time course of identification and resolution of verb gaps. ERPs were recorded while participants read sentences that contained a verb gap like Ron took/sanded the planks, and Bill ? the hammer... Plausibility of the critical words (hammer) that followed the verb gap was manipulated. Relative to the plausible control (preceded by took), ERPs to the critical word in the implausible condition (preceded by sanded) showed an N400, followed by a positivity (P600). ERPs to determiners following gapped verbs showed a negativity between 100 and 300 ms, and a positivity between 300 and 500 ms compared to determiners in non-gapping constructions. These results suggest that the sentence processor recognizes a verb gap and reconstructs the verb information at the earliest possible occasion, and that this reconstruction process is different from the reconstruction of antecedents in other filler-gap constructions (e.g., WH gaps).     

Dissociating prelexical and postlexical processing of affective information in the two hemispheres: effects of the stimulus presentation format

Using a lexical decision task, the authors investigated whether brain asymmetries in the detection of emotionally negative semantic associations arise only at a perceptually discriminative stage at which lexical analysis is accurate or can already be found at crude and incomplete levels of perceptual representation at which word-nonword discrimination is based solely on guessing. Emotionally negative and neutral items were presented near perceptual threshold in the left and right visual hemifields. Word-nonword discrimination performance as well as the bias to classify a stimulus as a "word" (whether or not it actually is a word) were assessed for a normal, horizontal stimulus presentation format (Experiment 1) and for an unusual, vertical presentation format (Experiment 2). Results show that while the two hemispheres are equally able to detect affective semantic associations at a prelexical processing stage (both experiments), the right hemisphere is superior at a postlexical, perceptually discriminative stage (Experiment 2). Moreover, the findings suggest that only an unusual, nonoverlearned stimulus presentation format allows adequate assessment of the right hemisphere's lexical-semantic skills.