Terminal Words Research Articles

Phonological activation in chinese reading: an event-related potential study using low-resolution electromagnetic tomography

The aim of the present study was to examine the pattern of phonological activation during Chinese sentence reading. Terminal words in high cloze sentences were manipulated across six conditions defined by word frequency and ending types. The P200 was smaller for the congruent targets than for the unrelated control targets, while there were no differences between the homophonic and unrelated control targets. No frequency effect on the P200 was observed. More importantly, a reduced N400 to the homophonic words was observed independent of word frequency. Source analysis by low resolution electromagnetic tomography (LORETA) revealed that the highly activated areas for the P200 were located at bilateral superior frontal (BA 6) and occipital (BA 17, 18 and 19) areas, while the N400 was located at left medial frontal (BA 6) area. These findings suggest that phonology is activated automatically for both high- and low-frequency words during Chinese sentence reading, even when the task is not focused on pronunciation.

Semantic processing of mathematical gestures

Objective To examine whether or not university mathematics students semantically process gestures depicting mathematical functions (mathematical gestures) similarly to the way they process action gestures and sentences. Semantic processing was indexed by the N400 effect. Results The N400 effect elicited by words primed with mathematical gestures (e.g. “converging” and “decreasing”) was the same in amplitude, latency and topography as that elicited by words primed with action gestures (e.g. drive and lift), and that for terminal words of sentences. Significance and conclusion Findings provide a within-subject demonstration that the topographies of the gesture N400 effect for both action and mathematical words are indistinguishable from that of the standard language N400 effect. This suggests that mathematical function words are processed by the general language semantic system and do not appear to involve areas involved in other mathematical concepts (e.g. numerosity).

Two collapsing hierarchies of subregularly tree controlled languages

Tree controlled grammars are context-free grammars where the associated language only contains those terminal words which have a derivation where the word of any level of the corresponding derivation tree belongs to a given regular language. In this paper, we consider first as control sets such regular languages which can be represented by finite unions of monoids. We show that the corresponding hierarchy of tree controlled languages collapses already at the second level. Second, we restrict the number of states allowed in the accepting automaton of the regular control language. We prove that the associated hierarchy has at most five levels.

Word boundary detection based on suprasegmental features: A case study on Bangla speech

This paper proposes a method for detecting word boundaries in continuous speech signal for Standard Colloquial Bengali (SCB), commonly referred to as Bangla. Bangla is a bound stress language with stress on the first syllable. Stress introduces its signature on the supra-segmental parameters of the speech signal, which may help to detect the word boundary in the continuous speech signal. The parameters used in this present study are: (1) Difference of the nucleus vowel duration across the syllable boundary, (2) Difference of the normalized nucleus vowel power across the syllable boundary, (3) Normalized F0 difference across the syllable boundary, (4) Difference of the average normalized F0 across the syllable boundary, (5) Difference of the normalized maximum periodic power of nucleus vowels across the syllable boundary, (6) Onset duration of the nucleus vowel. Altogether 225 sentences spoken by five native Bangla informants of both the sexes, in the age group of 20–50 years in normal laboratory environment are used in this study. These sentences contain 2734 syllables and 1103 words, sentence terminal words being excluded. A recognition score of 87.8% with a classifier, based on a distance function, weighted by inverse of variance is reported. Both speaker dependent as well as speaker independent studies are included.

Psychopathy and semantic processing: An examination of the N400

Accumulating evidence suggests that psychopathy is associated with behavioral and event-related potential (ERP) abnormalities during semantic language tasks. Psychopaths’ ERP abnormalities are most prominent in the 300–500 ms post-stimulus time window. It is unclear whether these ERP differences are related to neurocognitive processes associated with the P300 (i.e., poor attention/orienting/working memory) or N400 (i.e., aberrant semantic processes). To address this issue, the present study employed a canonical semantic sentence processing paradigm known to selectively elicit the N400. Fifty incarcerated participants were divided into psychopathic ( n = 25) or nonpsychopathic ( n = 25) groups based on scores from the Hare Psychopathy Checklist-Revised. The N400 and P600 components elicited by terminal words of sentences either congruent or incongruent with the previous sentence context were examined. No differences were observed between groups in the behavioral or ERP data. These data do not support the hypothesis that the semantic processes, and underlying neural systems, associated with the generation of the N400 during sentence processing tasks are abnormal in psychopathy.

Spoken word recognition in context: Evidence from Chinese ERP analyses

Two event-related potential (ERP) experiments were conducted to investigate spoken word recognition in Chinese and the effect of contextual constraints on this process. In Experiment 1, three kinds of incongruous words were formed by altering the first, second or both syllables of the congruous disyllabic terminal words in high constraint spoken sentences. Results showed an increase of N400 amplitude in all three incongruous word conditions and a delayed N400 effect in the cohort incongruous condition as compared with the rhyme incongruous and plain incongruous condition. In addition, unlike results in English, we found that the N400 effect in the rhyme incongruous condition disappeared earlier than in the plain incongruous condition. In Experiment 2, three kinds of nonwords derived from sentence congruous words were constructed by altering few or many phonetic features of the onset or the whole of the first syllable, and the resulting nonwords appeared as disyllabic terminal forms in either high or low constraint sentences. All three nonword conditions elicited the N400 component. In addition, in high constraint sentences but not in low, the amplitude and duration of the N400 varied as a function of the degree of phonetic mismatch between the terminal nonword and the expected congruous word.

The influence of increased working memory load on semantic neural systems: a high-resolution event-related brain potential study

The effects of working memory (WM) on the semantic N400 response were studied using high-resolution event-related brain potentials (ERPs). Participants were presented with semantically related sentence pairs and the terminal word congruence was varied in the second sentence. WM load was varied for the sentence pairs using a modified fan procedure [J.R. Anderson, Retrieval of propositional information from long-term memory. Cogn. Psychol., 6 (1974) 451–474; J.R. Anderson, A spreading activation theory of memory. J. Verbal Learn. Verbal Behav., 22 (1983) 261–295]. ERPs were recorded to the onset of the terminal word (Congruent and Incongruent) for sentence pairs at two levels of WM load (WML1 and WML2). Behavioral data analysis revealed that reaction times (RTs) increased as a function of WM load (i.e., the fan effect). Semantically incongruent words elicited an N400 response. Increased WM load reduced the congruency effect and, importantly, resulted in a significant delay in N400 peak latency (∼50 ms). Moreover, the latency delay was correlated with a neuropsychological measure of individual WM capacity. WM load effects on the N400 were interpreted as a result of competing activation in WM, both modulating semantic expectancies and delaying semantic integration. Exploratory source analysis revealed activation in occipital, temporal, and parietal regions. Consistent with prior reports on the N400 and semantic processing, equivalent current dipoles were modeled in the left perisylvian region. Increased WM load led to novel source activation in the left inferior parietal region as well as increased activation levels in anterior temporal sources. The source modeling results were in agreement with the functional roles typically ascribed to these areas and confirmed that the scalp-recorded WM load effects on the N400 were present within the intracranial generators.

Inhibitory Control During Sentence Reading in Dyslexic Children

The present study focused on the nature of the reading disability of children with the guessing subtype of dyslexia (who read fast and inaccurately). The objective was to separate the excitatory account of their reading disturbance (i.e., in guessers the words' resting levels of activation are oversensitive to semantic context) from the inhibitory account (i.e., guessers tend to react prematurely to (false) candidate words that are activated in the lexicon). To disentangle the above accounts, guessers and normal readers were presented with a sentential priming task (SPT). In the SPT, subjects had to determine whether the final word of a sentence was semantically congruent or incongruent with the sentence, but had to inhibit their 'congruent' or 'incongruent' response in case of an occasionally presented pseudoword. To evoke guessing, each pseudoword closely resembled either a valid congruent or incongruent word. Guessing referred to prematurely accepting a pseudoword as a word that either appropriately or inappropriately completed the sentence. The extent to which subjects guessed at word meaning was evidenced by the false recognition rates (FRR) of the misspelled terminal words. Analyses on the FRRs of the pseudowords showed that guessers had significantly more difficulty in suppressing the 'go tendency' triggered by the pseudowords. It was concluded that the impulsive reading style of guessers should be ascribed to a less efficient suppression mechanism rather than to excessive reliance on contextual information. Specifically, the data were explained by assuming that the availability of the pseudoword's candidate meaning activated the hand to respond with, and that guessers found difficulty in suspending this response until they analyzed all letters in the stimulus and they could be sure of its spelling.

Inhibitory Control During Sentence Reading in Dyslexic Children

The present study focused on the nature of the reading disability of children with the guessing subtype of dyslexia (who read fast and inaccurately). The objective was to separate the excitatory account of their reading disturbance (i.e., in guessers the words’ resting levels of activation are oversensitive to semantic context) from the inhibitory account (i.e., guessers tend to react prematurely to (false) candidate words that are activated in the lexicon). To disentangle the above accounts, guessers and normal readers were presented with a sentential priming task (SPT). In the SPT, subjects had to determine whether the final word of a sentence was semantically congruent or incongruent with the sentence, but had to inhibit their ‘congruent’ or ‘incongruent’ response in case of an occasionally presented pseudoword. To evoke guessing, each pseudoword closely resembled either a valid congruent or incongruent word. Guessing referred to prematurely accepting a pseudoword as a word that either appropriately or inappropriately completed the sentence. The extent to which subjects guessed at word meaning was evidenced by the false recognition rates (FRR) of the misspelled terminal words. Analyses on the FRRs of the pseudowords showed that guessers had significantly more difficulty in suppressing the ‘go tendency’ triggered by the pseudowords. It was concluded that the impulsive reading style of guessers should be ascribed to a less efficient suppression mechanism rather than to excessive reliance on contextual information. Specifically, the data were explained by assuming that the availability of the pseudoword’s candidate meaning activated the hand to respond with, and that guessers found difficulty in suspending this response until they analyzed all letters in the stimulus and they could be sure of its spelling.

Determining the role of phonology in silent reading using event-related brain potentials

The goal of the present study was to delineate phonology's role in silent reading using event-related brain potential (ERP) techniques. Terminal endings of high cloze sentences were manipulated in four conditions in which the terminal word was: (1) the high cloze ending and thus orthographically, phonologically and semantically congruent (e.g., The gambler had a streak of bad luck.); (2) a pseudohomophone that was orthographically incongruent, but was phonologically congruent to the anticipated ending (e.g., The ship disappeared into the thick phog [fog].); (3) a word that was orthographically, phonologically and semantically incongruent to expectations (e.g., The dog chased the cat up the Queen [tree].); or (4) a nonword and consequently orthographically, phonologically and semantically incongruent to expectations (e.g., The gas station is about two miles down the bole [road].). A N270 was elicited by orthographically incongruent words and nonwords (conditions 2, 3 and 4), likely reflecting violations of orthographic form expectations, while the presence of the N400 to semantically incongruent words and nonwords (conditions 3 and 4) reflected violations of semantic expectations. The relative absence of the N400 response to pseudohomophones (condition 3) indicates that integrating word meaning with sentential context is influenced by the phonological representation of the presented letter string. The implication of these results for theories of word recognition is discussed.

On differentiation functions, structure functions, and related languages of context-free grammars

We introduce the notion of a differentiation function of a context-free grammar which gives the number of terminal words that can be derived in a certain number of steps. A grammar is called narrow (or k -narrow) iff its differentiation function is bounded by a constant (by k ). We present the basic properties of differentiation functions, especially we relate them to structure function of context-free languages and narrow grammars to slender languages. We discuss the decidability of the equivalence of grammars with respect to the differentiation function and structure function and prove the decidability of the k -narrowness of context-free grammars. Furthermore, we introduce languages representing the graph of the differentiation and structure function and relate these languages to those of the Chomsky hierarchy.

Contextual modulation of N400 amplitude to lexically ambiguous words

Though much is known about the N400 component, an event-related EEG potential that is sensitive to semantic manipulations, it is unclear whether modulations of N400 amplitude reflect automatic processing, controlled processing, or both. We examined this issue using a semantic judgment task that manipulated local and global contextual cues. Word triplets (prime–noun–target, e.g., finance–bank–money) were sequentially presented on a computer screen (500 ms duration, 1000 ms stimulus onset asynchrony), in which the second word was a homograph. The first word (prime) created a neutral-, dominant-meaning- or subordinate-meaning-biased “global context,” and the third word (target) created a dominant- or subordinate-biased “local context” that was either congruent or incongruent with the “global context” established by the first prime word. Participants were instructed to read all three words but to decide only whether the second and third words were semantically related. Event-related potentials (ERPs), specifically the N400, were recorded to the third terminal word. N400 amplitudes evoked by dominant meaning-related third words incongruent with the globally biased subordinate context (e.g., river–bridge–money) were significantly more negative than dominant endings in neutral contexts (e.g., taxi–bank–money), but not different from unrelated filler triplets. In addition, there was some indication that left hemisphere, temporal–parietal electrode sites were associated with greater N400 negativity for dominant targets in conflicting subordinate global contexts than homologous right hemisphere electrode sites, the latter of which showed significant activation to subordinate meanings in cooperating contexts. Thus, N400 amplitude was more affected by global than local context suggesting that controlled processes may take priority over automatic processes in modulating N400 amplitude, especially for left hemisphere electrode sites.

Event-related potentials reveal the effects of altering personal identity.

Subjects were presented with terminal words that identified a sentence to reflect their true selves or another irrelevant individual. Subjects were asked to push one button if the statement reflected their true identity and another if it did not. The ERP to the terminal word consisted of a double-peaked positivity. Both the initial P300 (peaking between 300-350 ms) and a later P550 (peaking between 550 and 575 ms) were significantly larger to words that reflected the subject's true identity. When subjects were asked to take on a new identity, the P300 became larger to new, false words but the later P550 was large to both the false and the true words. The P550 to true identity words became smaller over a period of 3 days as subjects rehearsed their new roles. However, the P550 remained large to the false identity words although it was now attenuated relative to the true identity words. The late positivities may reflect a complex decisional process involving at least two stages. The initial stage might the initial yes-no decision. The later positivity may reflect the personal relevance of the terminal word. In this case, one's own true identity only begins to lose its relevance after time, and enacting the false identity then increases the positivity to this new identity.

Neurophysiological efficiency in male and female alcoholics

Chronic alcoholics often exhibit impairment in behavioral indicators of cognitive efficiency. However, potential neurophysiological correlates of this deficit are understudied. To examine this function, semantic expectancy was measured by recording the N400 component of the event-related potential (ERP), which is elicited by incongruent semantic information. Abstinent alcoholics, 21–45 days sober ( n=26; 12 males, 14 females), as well as age and education equated community controls ( n=26; 12 males, 14 females), were instructed to read silently 218 sentences ending with either congruent, related/incongruent, or unrelated/incongruent terminal words. Difference waveforms to the terminal word were derived, and amplitude and latency measures of the most negative peak between 300 and 600 ms were obtained. Electrode sites included the midline sites, Fz, Cz, and Pz; the temporal sites T3 and T4; and parietal sites P3 and P4. Significant group effects in amplitude were observed for the difference waveform under the unrelated/incongruent condition at T3, T4, and P4 ( P≤.05). Measures at P3, Pz, Fz, and Cz approached significance ( P≤.15). Although the overall pattern did not change when regression techniques were used to control for age, only the T4 site retained significance ( P≤.05). Across all electrode sites, alcoholics produced reduced N400 amplitudes relative to community controls. Latency was unaffected. There were no group effects for amplitude or latency measures in the related/incongruent condition. These data are consistent with the hypothesis that alcoholics suffer from a subtle deficiency in neurophysiologically based cognitive efficiency which renders them less likely to respond appropriately to irrelevant information.

Differential activation of temporal cortex during sentence completion in schizophrenic patients with and without formal thought disorder

The neural correlates of processing linguistic context in schizophrenic patients with formal thought disorder (FTD) were examined. Six right-handed male patients with prominent ‘positive’ FTD were compared with six schizophrenic patients without FTD and seven volunteers, matched for cognitive and demographic variables. Functional magnetic resonance imaging (IMRI) was used to measure cerebral activation while subjects read and completed sentence stems out loud. During a GENERATION condition, subjects were required to generate a word which completed the sentence stem appropriately. During a DECISION condition, subjects selected and articulated one of two presented terminal words. A READING condition served as baseline. The three conditions were compared with each other. Regions activated were identified in each group, and between-group differences were detected using an ANCOVA. When GENERATION was compared with READING, FTD patients showed less activation in the right superior temporal gyrus than patients without FTD or controls, but greater activation in the left inferior frontal, inferior temporal and fusiform gyri. FTD patients also showed an attenuated right temporal response when GENERATION was compared with DECISION. This differential engagement of the right temporal cortex was independent of differences in the speed or accuracy of responses, whereas the left fronto–temporal differences in activation were not evident after covarying for task errors. The attenuated engagement of right temporal cortex, which is implicated in language comprehension at the discourse level, is consistent with neuropsychological evidence linking thought disorder with deficits in processing linguistic context.

Auditory memory in congenitally blind adults: a behavioral-electrophysiological investigation

Blind people must rely more than sighted people on auditory input in order to acquire information about the world. The present study was designed to test the hypothesis that blind people have better memory than sighted individuals for auditory verbal material and specifically to determine whether memory encoding and/or retrieval are improved in blind adults. An incidental memory paradigm was employed in which 11 congenitally blind people and 11 matched sighted controls first listened to 80 sentences which ended either with a semantically appropriate or inappropriate word. Immediately following, the recognition phase occurred, in which all sentence terminal words were presented again randomly intermixed with the same number of new words. Participants indicated whether or not they had heard the word in the initial study phase. Event-related brain potentials (ERPs) were recorded from 28 electrode positions during both the encoding and the retrieval phase. Blind participants’ memory performance was superior to that of sighted controls. In addition, during the recognition phase, previously presented words elicited ERPs with larger positive amplitudes than new words, particularly over the right hemisphere. During the study phase, words that would subsequently be recognized elicited a more pronounced late positive potential than words that were not subsequently recognized. These effects were reliable in the congenitally blind participants but could only be obtained in the subgroup of sighted participants who had the highest memory performance. These results imply that blind people encode auditory verbal material more efficiently than matched sighted controls and that this in turn allows them to recognize these items with a higher probability.

Engagement of right temporal cortex during processing of linguistic context

Language processing involves the interplay of areas in both cerebral hemispheres. Whereas the left temporal lobe is necessary for most language tasks, the right hemisphere seems to be additionally activated during processing of paragraphs and metaphors. We studied the neural correlates of word generation and selection in a sentence context, using functional magnetic resonance imaging (fMRI). Cerebral activation was measured while seven healthy, right handed volunteers read and completed sentence stems, with relatively low Cloze frequency, out loud. During a GENERATION condition, subjects were required to generate a word which completed a sentence stem appropriately. During a DECISION condition, subjects selected and articulated one of two presented terminal words. A READING condition in which subjects read an appropriate completion aloud, served as baseline. When GENERATION was compared to READING or DECISION, the left middle frontal, anterior cingulate, precuneus and right lateral temporal cortex were activated. During DECISION relative to READING, the left inferior frontal and middle/superior temporal cortex bilaterally were activated. The prominent engagement of the right lateral temporal cortex during the GENERATION conditions may reflect the processing of linguistic context, and particularly the activation of multiple meanings in the course of producing an appropriate completion.

Language‐Related Potentials in Temporal Lobe Epilepsy Before and After Surgical Treatment

Purpose: Temporal lobectomy has contributed to treatment for medically intractable epilepsies. However, influence of the surgical treatment on cognitive function is not still clear, especially from the electrophysiological viewpoint. N400, an event related potential (ERP) named for its negative polarity and peak latency of 400 ms, is reported to be an electrophysiological sign of neural activities associated with semantic priming in language perception. In the present study, ERPs are applied to evaluate the cognitive function of temporal lobe epilepsy before and after temporal lobectomy. Methods: Two patients with intractable temporal lobe epilepsy participated in this study. Fifteen normal subjects served as controls. The incongruous sentence task (Kutas and Hillyard 1980) was used to record N400 components in an auditory modality. Two types of sentences (40 Japanese sentences for each type) were prepared, in which the terminal words were either semantically congruent or incongruent. The scntences were randomly presented at approximately 65 dB SPL peak intensity. ERPs were recorded according to the international 10–20 system, with a balanced non‐cephalic electrode reference and 2 1 channels. The band‐pass filter was set from 0.5 to 30 Hz, and the ERPs were sampled at 500 Hz from 200 ms before the onset of terminal words to 824 ms post‐stimulus. Waves were calculated by subtracting ERPs in the congruent condition from those in the incongruent condition. N400 was scored as the most negative point between 250 and 450 ms in the subtraction waves. Amplitudes were measured from the baseline of 100 ms before the terminal words. Motor responses were also measured with a right index finger, to estimate the accuracy of understanding sentences. Results: Case I was a 22‐year‐old male who had intractable epilepsy for 7 years. Magnetic resonance imaging (MRI) showed high‐intensity signals in the right amygdalo‐hippocampal region. The epileptic seizures were confirmed to originate from the region hy electroencephalography/closed‐circuit television monitoring, and single‐photon‐emission computed tomography. ERPs were recorded I month before and after the right anterior temporal lobectomy. Before the surgery, the rate of correct responses showed no difference between the patient (96 %) and the controls (96 %). The amplitudes of N400 for the patient reduced in the right frontal and central areas (F4, C4), comparing to 99 % confidence limit for control subjects. After the surgery, the rate of correct responses was 97 %, and the amplitudes reduced in the right central, parietal, and posterior temporal areas (C4, P4, 0 2, T6). Case 2 (37‐year‐old female) had intractable epilepsy for 30 years. MRI showed brain atrophy in the right hippocampal region. The epileptic seizures were confirmed to originate from the region. N400 was recorded 3 months after the resection. The rate of correct responses was 95 %. The amplitudes of N400 were lower in the right frontal, parietal, and temporal areas (electrodes Fp2, F4, P4, T6, Pz), comparing to 99 % confidence limit of controls. Conclusions: Before the lpbectomy, the reduction of amplitudes of N400 indicated that the pathogenesis of intractable temporal lobe epilepsy would influence the process of semantic priming in language perception. After the resection, it was suggested that the right temporal lobectomy might affect the cognitive function in the brain from electrophysiological aspects. We could benefit from further study including analysis of the discrepancy between the amplitudes of N400 and behavioral responses.

The effects of rime on auditory recency and the suffix effect

Two experiments are reported that consider the role of rime as the content of Precategorical Acoustic Storage (PAS). It was hypothesised that with auditory presentation of lists the rime component of the final item (the final vowel and, optionally, terminal consonant cluster of a word) was preserved in PAS and this served as a recall cue to identify the final item. Experiment 1 compared recall performance when the terminal or penultimate words rhymed with an irrelevant stimulus suffix. A suffix that shared a rime with the terminal word was found to attenuate the suffix effect, in line with Carr and Miles (1997) and consistent with the use of PAS as a positional code. However, contrary to the hypothesis that PAS information is automatically used to reconstruct the final item, the suffix effect was no greater when the suffix rhymed with the penultimate item than when no relationship existed between the suffix and the final item. Experiment 2 demonstrated that when the terminal and penultimate words shared a rime there was a drop in recall performance for the final item but a corresponding increase in correct recall of the penultimate item. No such changes were observed when the rime was shared between terminal and antepenultimate items. It is suggested that adjacency of identical rimes allows improved reconstruction of item information at the expense of order information.

Terminating left-hand sides of scattered context productions M. Nivat

The left-hand side of a scattered context production, (A 1,A 2,…,A n) → (x 1,x 2,…,x n) , is terminating if A 1A 2…A n derives a terminal word. This paper discusses scattered context grammars whose sentential forms contain sequences of nonterminals formed by shuffling the terminating left-hand sides of productions. It proves that these grammars do not generate some context-sensitive languages, so they are less powerful than the scattered context grammars whose sentential forms are unrestricted. In its conclusion, this paper demonstrates the impact of this result and discusses open problems.