Auditory language comprehension: an event-related fMRI study on the processing of syntactic and lexical information

The functional specificity of different brain areas recruited in auditory language processing was investigated by means of event-related functional magnetic resonance imaging (fMRI) while subjects listened to speech input varying in the presence or absence of semantic and syntactic information. There were two sentence conditions containing syntactic structure, i.e., normal speech (consisting of function and content words), syntactic speech (consisting of function words and pseudowords), and two word-list conditions, i.e., real words and pseudowords. The processing of auditory language, in general, correlates with significant activation in the primary auditory cortices and in adjacent compartments of the superior temporal gyrus bilaterally. Processing of normal speech appeared to have a special status, as no frontal activation was observed in this case but was seen in the three other conditions. This difference may point toward a certain automaticity of the linguistic processes used during normal speech comprehension. When considering the three other conditions, we found that these were correlated with activation in both left and right frontal cortices. An increase of activation in the planum polare bilaterally and in the deep portion of the left frontal operculum was found exclusively when syntactic processes were in focus. Thus, the present data may be taken to suggest an involvement of the left frontal and bilateral temporal cortex when processing syntactic information during comprehension.     

Regional cerebral blood flow during comprehension and speech (in cerebrally healthy subjects)

Regional cerebral blood flow (rCBF) was measured by the xenon-133 inhalation method in 10 cerebrally healthy subjects at rest and during linguistic activation tests. These consisted of a comprehension test (binaural listening to a narrative text) and a speech test (making sentences from a list of words presented orally at 30-s intervals). The comprehension task induced a moderate increase in the mean right CBF and in both inferior parietal areas, whereas the speech test resulted in a diffuse increase in the mean CBF of both hemispheres, predominating regionally in both inferior parietal, left operculary, and right upper motor and premotor areas. It is proposed that the activation pattern induced by linguistic stimulation depends on not only specific factors, such as syntactic and semantic aspects of language, but also the contents of the material proposed and the attention required by the test situation.     

Brain imaging of tongue-twister sentence comprehension: twisting the tongue and the brain

This study used fMRI to investigate the neural basis of the tongue-twister effect in a sentence comprehension task. Participants silently read sentences equated for the syntactic structure and the lexical frequency of the constituent words, but differing in the proportion of words that shared similar initial phonemes. The manipulation affected not only the reading times and comprehension performance, but also the amount of activation seen in a number of language-related cortical areas. The effect was not restricted to cortical areas known to be involved in articulatory speech programming or rehearsal processes (the inferior frontal gyrus and anterior insula), but also extended to areas associated with other aspects of language processing (inferior parietal cortex) associated with phonological processing and storage.     

Auditory language comprehension: an event-related fMRI study on the processing of syntactic and lexical information

The functional specificity of different brain regions recruited in auditory language processing was investigated by means of event-related functional magnetic resonance imaging (fMRI) while subjects listened to speech input varying in the presence or absence of semantic and syntactic information. There were two sentence conditions containing syntactic structure, i.e., normal speech (consisting of function and content words), syntactic speech (consisting of function words and pseudowords), and two word-list conditions, i.e., real words and pseudowords. The processing of auditory language, in general, correlates with significant activation in the primary auditory cortices and in adjacent compartments of the superior temporal gyrus bilaterally. Processing of normal speech appeared to have a special status, as no frontal activation was observed in this case but was seen in the other three conditions. This difference may point toward a certain automaticity of the linguistic processes used during normal speech comprehension. When considering the three other conditions, we found that these were correlated with activation in both left and right frontal cortices. An increase of activation in the planum polare bilaterally and in the deep portion of the left frontal operculum was found exclusively when syntactic processes were in focus. Thus, the present data may be taken to suggest an involvement of the left frontal and bilateral temporal cortex when processing syntactic information during comprehension.     

The timing of shifts of head postures during conservation

The timing of shifts of head postures in relation to speech during conservation was investigated by continuously monitoring, with a polarised light goniometer, the head movement of four subjects engaged in conservation.Postural shifts (PSs), defined as wide, linear movements, were found to occur primarily towards the initiation of speech, be it between speaking turns, or between syntactic boundaries inside speaking turns. This suggested that PSs are involved in regulating turn taking and marking syntactic boundaries inside speaking turns.Also, PSs usually started prior to and continued till after speech onset. This suggested a possible involvement in speech production, probably in helping to regulate the complex motor processes of beginning to speak.It is suggested that interactive, linguistic and speech productive functions may combine together to create a movement pattern by mutually constraining head movement.     

The roles of sequencing and verbal working memory in sentence comprehension deficits in Parkinson's disease

Studies of sentence comprehension deficits in Parkinson's disease (PD) patients suggest that language processing involves circuits connecting subcortical and cortical regions. Anatomically segregated neural circuits appear to support different cognitive and motor functions. To investigate which functions are implicated in PD comprehension deficits, we tested comprehension, verbal working memory span, and cognitive set-switching in a non-linguistic task in 41 PD patients; we also obtained speech measurements reflecting motor sequencing processes that may be involved in articulatory rehearsal within working memory. Comprehension of sentences with center-embedded or final relative clauses was impaired when they could not be understood from lexical semantic content alone. Overall comprehension error rates correlated strongly with impaired set-switching and significantly with reduced working memory span and speech motor sequencing deficits. Correlations with comprehension of different sentence structures indicate that these impairments do not represent a single deficit; rather, PD comprehension deficits appear to arise from several independent mechanisms. Deficits in cognitive set-switching or underlying inhibitory processes may compromise the ability to process relative clauses. Deficits in verbal working memory appear to impair comprehension of long-distance dependencies. Speech sequencing correlated with neither set-switching nor verbal working memory span, consistent with their being supported by independent, segregated cortico-subcortical circuits.     

Sounds, words, sentences: age-related changes across levels of language processing

Age-related changes in sensory, lexical, and sentence processing were examined and compared using event-related potentials (ERPs) recorded as young and elderly participants listened to natural speech for comprehension. Lexically associated and unassociated word pairs were embedded in meaningful or syntactically legal but meaningless sentences. Early, general sensory, and attention-related responses (N1, P2) were delayed by about 25 ms for older participants, but later components indexing semantic processing (N400) were not delayed. There were no differences in the size, timing, or distribution of lexical associative effects for the two groups. In contrast, message-level context effects were delayed by more than 200 ms in the elderly group. The results support models that posit age-related changes primarily in higher order language processes.     

Where do dialectal effects on speech processing come from? Evidence from a cross-dialect investigation

Accented speech has been seen as an additional impediment for speech processing; it usually adds linguistic and cognitive load to the listener's task. In the current study we analyse where the processing costs of regional dialects come from, a question that has not been answered yet. We quantify the proficiency of Basque–Spanish bilinguals who have different native dialects of Basque on many dimensions and test for costs at each of three levels of processing–phonemic discrimination, word recognition, and semantic processing. The ability to discriminate a dialect-specific contrast is affected by a bilingual's linguistic background less than lexical access is, and an individual's difficulty in lexical access is correlated with basic discrimination problems. Once lexical access is achieved, dialectal variation has little impact on semantic processing. The results are discussed in terms of the presence or absence of correlations between different processing levels. The implications of the results are considered for how models of spoken word recognition handle dialectal variation.     

Automatic and controlled processes in the first- and second-language reading of fluent bilinguals

Many fluent bilinguals read their two languages with equal levels of comprehension but read their second language at a slower rate. The present study examined whether, compared with first language reading, slower second-language reading is associated with reduced involvement of automatic processing during lexical access. Subjects were bilinguals with fluent speaking and listening skills under ordinary conditions of communication and with equivalent comprehension of their first and second languages when reading and listening under speeded conditions. Half these subjects, however, read their first and second languages equally fast, and half read the second language more slowly than the first. Subjects were tested on a lexical decision task that manipulated expectations about the semantic relatedness of prime and target words and the stimulus onset asynchrony between them. Bilinguals with equal first- and second-language reading rates produced in each language a pattern of reaction times suggesting automatic processing, whereas bilinguals with a slower second-language reading rate did so in their first language but not in their second.     

Automatic syntactic computation and use of semantic information during sentence comprehension

Summary The paper represents a contribution to the issue of the differential effects of syntactic, semantic and pragmatic information in the process of sentence comprehension. The results of four experiments are reported, in which sentences containing syntactic, semantic and pragmatic violations were presented with different tasks to see how these violations affected language comprehension, how easily they were detected and whether they affected sentence comprehension even when they were not explicitly recognized. The main results can be summarized as follows. First, the most relevant cues used to comprehend a sentence are not so much syntactic, but semantic or pragmatic. Second, with difficult or anomalous linguistic input, syntactic cues become more important. Third, even when the reader is not aware of syntactic violations, these seem to affect his processing of the linguistic input. This suggests the hypothesis of an automatic computation of syntactic information, the output of which is, however, used only when evidence coming from other sources, semantic or pragmatic, is insufficient or not clear enough.     

句子理解的关键——对句法和语义关系的再探讨

对于句子理解中句法和语义的关系,传统的模块化观点认为,句法信息优先于语义信息,句法加工支配着句子的理解过程。近期,这种强调句法优先的理论受到了一系列ERP（Event-related potentials）研究结果的挑战,这些研究从不同角度论证了语义信息对句法加工及句子整合加工的重要作用。基于这些研究发现,研究者提出句子理解过程中句法和语义的关系并非一成不变：一些情况下可能是句法支配语义加工,而另一些情况下则可能是语义引导句法加工     

中文阅读之句法分析历程初探

该文报告的是香港中文大学心理学系的认知心理实验室中最近完成的两个与句法分析有关的实验。第一个实验探讨阅读中文时词汇、句法以及语意资料之触发和运用的时序问题。第二个实验研究的是中文读者所使用的句法分析策略。在两个实验中,基本的作业是让被试阅读在电脑屏幕上呈现的短文。文中每个字的阅读时间则由电脑记录作为反映阅读理解即时处理历程的指标。文中除了报告实验的结果外,还依据这些结果讨论了读者在阅读中文时所使用的句法分析策略以及句法资料的触发和使用历程。     

句子理解过程中句法与语义加工的EEG时频分析

EEG时频分析旨在通过测量单个电极各频段的能量变化, 揭示事件相关振荡活动。采用该技术, 最近的句子加工研究发现, 句法与语义过程均与多个频段(θ、a、b或γ)能量变化相联系。此外, 不同方面的句法(如语法性、数)和语义加工(语义整合或预期)与不同频段振荡活动相联系。将来的研究应该使用多种EEG能量计算方法, 在多种语言中, 探讨时态、词序等句法加工所伴随的振荡活动, 特别是句法和语义过程相互作用在EEG能量变化上的表现。     

Perceptual and motor attribute ratings for 559 object concepts

To understand how and when object knowledge influences the neural underpinnings of language comprehension and linguistic behavior, it is critical to determine the specific kinds of knowledge that people have. To extend the normative data currently available, we report a relatively more comprehensive set of object attribute rating norms for 559 concrete object nouns, each rated on seven attributes corresponding to sensory and motor modalities??color, motion, sound, smell, taste, graspability, and pain??in addition to familiarity (376 raters, M = 23 raters per item). The mean ratings were subjected to principal-components analysis, revealing two primary dimensions plausibly interpreted as relating to survival. We demonstrate the utility of these ratings in accounting for lexical and semantic decision latencies. These ratings should prove useful for the design and interpretation of experimental tests of conceptual and perceptual object processing.     

The effects of slowed speech on auditory comprehension in aphasia

The present study investigates the effects of slowed speech on auditory comprehension in aphasia. Specifically, an attempt was made to isolate the effects of added time on comprehension at the language processing stages of auditory perception, by increasing the duration of the vowel segments in each word; word recognition and semantic analysis, by adding silences between words; and syntactic analysis, by adding silences at constituent phrase boundaries. Sentences were also read at a slow rate to see the effects of naturally slowed speech on sentence comprehension. Test sentences consisted of simple active and passive declarative sentences, and complex sentences with embedded medial and final relative clauses. Sentences were either semantically reversible or nonreversible. Thirty-four aphasic patients who varied in both severity and type of aphasia were tested on a picture verification task. Results indicated that slowing facilitated language comprehension significantly only in the syntactic condition. Neither syntactic complexity nor semantic reversibility interacted with slowed speech to facilitate auditory language comprehension. Further, it was only the Wernicke's aphasics who showed significant improvement with time added at constituent boundaries. These results suggest that time alone does not facilitate language comprehension in aphasia, but that rather it is the interaction of time with syntactic processing which improves comprehension.     

The development of sentence interpretation: effects of perceptual, attentional and semantic interference

How does the development and consolidation of perceptual, attentional, and higher cognitive abilities interact with language acquisition and processing? We explored children's (ages 5–17) and adults’ (ages 18–51) comprehension of morphosyntactically varied sentences under several competing speech conditions that varied in the degree of attentional demands, auditory masking, and semantic interference. We also evaluated the relationship between subjects’ syntactic comprehension and their word reading efficiency and general ‘speed of processing’. We found that the interactions between perceptual and attentional processes and complex sentence interpretation changed considerably over the course of development. Perceptual masking of the speech signal had an early and lasting impact on comprehension, particularly for more complex sentence structures. In contrast, increased attentional demand in the absence of energetic auditory masking primarily affected younger children's comprehension of difficult sentence types. Finally, the predictability of syntactic comprehension abilities by external measures of development and expertise is contingent upon the perceptual, attentional, and semantic milieu in which language processing takes place.     

Lexical and conceptual factors in the naming of relations

Recent models of language production distinguish three main stages, the generation of a preverbal (or conceptual) message level representation, the stage of linguistic formulation processes (which access lexical items and generate the syntactic frames in which these items are inserted), and the stage of articulation. This means that at least two sources of difficulty in producing a lexical item must be distinguished. First, the difficulty can be due to properties of the message representation. So, for example, several concepts may compete for expression. Second, a given lexical item might be more difficult to access than another item because of differences in the complexity of the processes translating from conceptual to lexical representations. The present study presents evidence for these two sources of difficulty in producing lexical items for the domain of semantically unmarked versus marked dimensional adjectives (e.g., big versus small). The first set of experiments establishes an effect of semantic markedness in language production which is due to a difference in the difficulty of accessing unmarked versus marked lexical items. The second set of experiments shows that competition between concepts for expression can lead to incorrect selection of an (unintended) lexical item (as reflected in certain types of speech errors), or to a higher processing load for producing the correct (intended) lexical item. Together, these experiments support the distinction between a preverbal conceptual and a lexical level of representation in language production, and show that both levels contribute to the relative difficulty of producing lexical items.     

The neurology of syntax: language use without Broca's area

A new view of the functional role of the left anterior cortex in language use is proposed. The experimental record indicates that most human linguistic abilities are not localized in this region. In particular, most of syntax (long thought to be there) is not located in Broca's area and its vicinity (operculum, insula, and subjacent white matter). This cerebral region, implicated in Broca's aphasia, does have a role in syntactic processing, but a highly specific one: It is the neural home to receptive mechanisms involved in the computation of the relation between transformationally moved phrasal constituents and their extraction sites (in line with the Trace-Deletion Hypothesis). It is also involved in the construction of higher parts of the syntactic tree in speech production. By contrast, basic combinatorial capacities necessary for language processing--for example, structure-building operations, lexical insertion--are not supported by the neural tissue of this cerebral region, nor is lexical or combinatorial semantics. The dense body of empirical evidence supporting this restrictive view comes mainly from several angles on lesion studies of syntax in agrammatic Broca's aphasia. Five empirical arguments are presented: experiments in sentence comprehension, cross-linguistic considerations (where aphasia findings from several language types are pooled and scrutinized comparatively), grammaticality and plausibility judgments, real-time processing of complex sentences, and rehabilitation. Also discussed are recent results from functional neuroimaging and from structured observations on speech production of Broca's aphasics. Syntactic abilities are nonetheless distinct from other cognitive skills and are represented entirely and exclusively in the left cerebral hemisphere. Although more widespread in the left hemisphere than previously thought, they are clearly distinct from other human combinatorial and intellectual abilities. The neurological record (based on functional imaging, split-brain and right-hemisphere-damaged patients, as well as patients suffering from a breakdown of mathematical skills) indicates that language is a distinct, modularly organized neurological entity. Combinatorial aspects of the language faculty reside in the human left cerebral hemisphere, but only the transformational component (or algorithms that implement it in use) is located in and around Broca's area.