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PubMed2004

Implicit and explicit processing of kanji and kana words and non-words studied with fMRI.

Using functional magnetic resonance imaging (fMRI), we investigated the implicit language processing of kanji and kana words (i.e., hiragana transcriptions of normally written kanji words) and non-words. Twelve right-handed native Japanese speakers performed size judgments for character stimuli (implicit language task for linguistic stimuli), size judgments for scrambled-character stimuli (implicit language task for non-linguistic stimuli), and lexical decisions (explicit language task). The size judgments for scrambled-kanji stimuli and scrambled-kana stimuli produced activations on the bilateral lingual gyri (BA 18), the bilateral occipitotemporal regions (BA 19/37), and the bilateral superior and inferior parietal cortices (BA 7/40). Interestingly, besides these areas, activations of the left inferior frontal region (Broca's area, BA 44/45) and the left posterior inferior temporal cortex (PITC, BA 37), which have been considered as language areas, were additionally activated during size judgment for kanji character stimuli. Size judgment for kana character stimuli also activated Broca's area, the left PITC, and the left supramarginal gyrus (SMG, BA 40). The activations of these language areas were replicated in the lexical decisions for both kanji and kana. These findings suggest that language processing of both kanji and kana scripts is obligatory to literate Japanese subjects. Moreover, comparison between the scrambled kanji and the scrambled kana showed no activation in the language areas, while greater activation in the bilateral fusiform gyri (left-side predominant) was found in kanji vs. kana comparison during the size judgment and the lexical decision. Kana minus kanji activated the left SMG during the size judgment, and Broca's area and the left middle/superior temporal junction during the lexical decision. These results probably reflect that in implicit or explicit reading of kanji words and kana words (i.e., hiragana transcriptions of kanji words), although using largely overlapping cortical regions, there are still some differences. Kanji reading may involve more heavily visual orthographic retrieval and lexical-semantic system through the ventral route, while kana transcriptions of kanji words require phonological recoding to gain semantic access through the dorsal route.

Adult↗
PubMed2006

Understanding words in context: the role of Broca's area in word comprehension.

What role does meaning selection play in word comprehension, and what neural systems support this selection process? Most words have multiple meanings and are therefore ambiguous. This is true of both homonymous words (words that have multiple unrelated meanings) and polysemous words (words that have multiple related meanings). The extant evidence indicates that meaning selection is an integral part of homonym comprehension. However, it is not known whether meaning selection extends to polysemous words, or what neural systems support meaning selection during comprehension. Prior neuroimaging and neuropsychological evidence suggest that the left inferior frontal gyrus (LIFG) may play a role in resolving competition during language processing. We therefore sought to test the hypotheses that meaning selection is part of polysemous word comprehension, and that the LIFG resolves meaning competition during word comprehension. We tested healthy participants on a version of the triplet lexical decision task, with polysemous and homonymous stimuli. Results suggest that the meanings of polysemous words, like the meanings of homonyms, are selected based on context. However, homonymous and polysemous words differed in how meaning frequency affected meaning selection. We then administered the triplet lexical decision task to patients with LIFG damage to examine whether this region plays a role in context-dependent meaning selection. Results support the hypothesis that the LIFG serves as a top-down biasing mechanism that facilitates rapid meaning selection during word comprehension. We conclude that context-dependent meaning selection is an integral part of word comprehension for both homonyms and polysemous words, and that the LIFG facilitates this selection process.

Adult↗
PubMed1998

Anatomy of word and sentence meaning.

Reading and listening involve complex psychological processes that recruit many brain areas. The anatomy of processing English words has been studied by a variety of imaging methods. Although there is widespread agreement on the general anatomical areas involved in comprehending words, there are still disputes about the computations that go on in these areas. Examination of the time relations (circuitry) among these anatomical areas can aid in understanding their computations. In this paper, we concentrate on tasks that involve obtaining the meaning of a word in isolation or in relation to a sentence. Our current data support a finding in the literature that frontal semantic areas are active well before posterior areas. We use the subject's attention to amplify relevant brain areas involved either in semantic classification or in judging the relation of the word to a sentence to test the hypothesis that frontal areas are concerned with lexical semantics and posterior areas are more involved in comprehension of propositions that involve several words.

Adult↗
PubMedDate not supplied

Impaired visual attention in children with dyslexia.

Reading involves the correct and rapid identification of visual stimuli with letters and words. The processing of visual stimuli depends not only on the integrity of the peripheral and central visual system but also on the attentional systems involved. In the present study, a cue-target visual attention task was administered to a population-based sample of 25 children with dyslexia from 10 to 12 years of age. A control group matched for group size, age, and gender was obtained from the same general population. A two-stage screening process involved a spelling task of regular words followed by a battery of five single-word reading tasks. The cue-target task involved both a computer-controlled stimulus presentation and a computer-controlled measurement of reaction time. The data were analyzed by visual field, cue condition (valid, invalid, and no cue), and cue-target interval (CTI). The results showed a general pattern of slower responses in the dyslexia group compared to the control group. The dyslexia group also had longer reaction times in the short CTI condition (covert shift of attention) and in the long CTI condition (overt shift of attention). The findings may reflect a general attentional deficit to visual stimuli in dyslexia, possibly related to problems with the recruitment of necessary cognitive resources for the performance of complex reaction time tasks and for fluent reading.

Attention↗
PubMed1998

Effects of modality on subjective frequency estimates and processing of spoken and printed words.

Previous research (Garber & Pisoni, 1991; Pisoni & Garber, 1990) has demonstrated that subjective familiarity judgments for words are not differentially affected by the modality (visual or auditory) in which the words are presented, suggesting that participants base their judgments on fairly abstract, modality-independent representations in memory. However, in a recent large-scale study in Japanese (Amano, Kondo, & Kakehi, 1995), marked modality effects on familiarity ratings were observed. The present research further examined possible modality differences in subjective ratings and their implications for word recognition. Specially selected words were presented to participants for frequency judgments. In particular, participants were asked how frequently they read, wrote, heard, or said a given spoken or printed word. These ratings were then regressed against processing times in auditory and visual lexical decision and naming tasks. Our results suggest modality dependence for some lexical representations.

Humans↗
PubMed2006

The processing of lexical stress during visual word recognition: typicality effects and orthographic correlates.

Many studies that have examined reading at the single-word level have been restricted to the processing of monosyllabic stimuli, and, as a result, lexical stress has not been widely investigated. In the experiments reported here, we used disyllabic words and nonwords to investigate the processing of lexical stress during visual word recognition. In Experiments 1 and 2, we found an effect of stress typicality in naming and lexical decision. Typically stressed words (trochaic nouns and iambic verbs) elicited fewer errors than atypically stressed words (iambic nouns and trochaic verbs). In Experiment 3, we carried out an analysis of 340 word endings and found clear orthographic correlates of both grammatical category and lexical stress in word endings. In Experiment 4, we demonstrated that readers are sensitive to these cues in their processing of nonwords during two tasks: sentence construction and stress assignment. We discuss the implications of these findings with regard to psycholinguistic models of single-word reading.

Analysis of Variance↗
PubMed1999

Eye movement control during reading: foveal load and parafoveal processing.

We tested theories of eye movement control in reading by looking at parafoveal processing. According to attention-processing theories, attention shifts towards word n + 1 only when processing of the fixated word n is finished, so that attended parafoveal processing does not start until the programming of the saccade programming to word n + 1 is initiated (Henderson & Ferreira, 1990; Morrison, 1984), or even later when the processing of word n takes too long (Henderson & Ferreira, 1990). Parafoveal preview benefit should be constant whatever the foveal processing load (Morrison, 1984), or should decrease when processing word n outlasts an eye movement programming deadline (Henderson & Ferreira, 1990). By manipulating the frequency and length of the foveal word n and the visibility of the parafoveal word n + 1, we replicated the finding that the parafoveal preview benefit is smaller with a low-frequency word in foveal vision. Detailed analyses, however, showed that the eye movement programming deadline hypothesis could not account for this finding which was due not to cases where the low-frequency words n had received a long fixation, but to cases of a short fixations less than 240 msec. In addition, there was a spill-over effect of word n to word n + 1, and there was an element of parallel processing of both words. The results are more in line with parallel processing limited by the extent to which the parafoveal word processing on fixation n can be combined with the foveal word processing on fixation n + 1.

Cognition↗
PubMed2005

Activation shift from medial to lateral temporal cortex associated with recency judgements following impoverished encoding.

Recency judgements can be performed on the basis of across-event relational information that directly provides temporal order among past events. Non-relational item-based information internal to individual past events, such as information retrieved through familiarity, may also contribute to recency judgements. The present functional magnetic resonance imaging study examined neural substrates for item-based processing during recency judgements as an alternative to relational recency judgements. One half of word stimuli were encoded relationally prior to recency judgements, and the relational encoding of the other half was hampered such that the words were processed relatively in an item-based manner. Brain activity in the medial temporal lobe was observed during recency judgements for words studied with relational memory processing, whereas brain activity in the lateral temporal cortex was observed during recency judgements for words studied relatively in an item-based manner. It was revealed further that recognition of individual words per se, which can also be regarded as familiarity/recency judgements but is non-relational in nature, also activated the lateral temporal region. These results indicate multiple routes for recency judgements within the temporal lobe that are recruited depending on how past episodes are represented and retrieved for judgements of their temporal order.

Adult↗
PubMed2000

Processing lexical ambiguities in word triplets: evidence of lexical-semantic deficits following dominant nonthalamic subcortical lesions.

Lexical-semantic function was investigated in 10 participants with lesions of the dominant nonthalamic subcortical (NS) region and a matched normal control group. Participants performed speeded lexical decisions on the 3rd member of auditorily presented word triplets. The 4 critical triplet conditions were concordant (coin-bank-money), discordant (river-bank-money), neutral (day-bank-money), and unrelated (river-day-money). When the interstimulus interval (ISI) between the words in the triplets was 100 ms, patients with NS lesions obtained priming that indicated nonselective lexical access; at 1,250-ms ISI, however, there was no significant priming effect. This pattern of results is consistent with the view that patients with NS lesions can automatically access lexical-semantic information but may be unable to sustain lexical activation through controlled or attentional forms of processing.

Aged↗
PubMed1983

Aphasics' perception of words in sentential context: some real-time processing evidence.

The perception of words belonging to different grammatical classes was investigated in Wernicke's and Broca's aphasics. The experimental used a word monitoring task, which varied the target's word class, as well as the sentential context. The sensitivity to semantic context was very similar for both aphasic groups. Processing differences for the two groups were found, however, with respect to different word classes. It appears that Broca's aphasics are unable to process grammatical morphemes as features of a phrasal frame. Wernicke's aphasics, however, seem to retain the ability to process syntactic as well as some semantic information, at least, during sentence perception.

Adult↗
PubMed2006

The context-specific proportion congruent Stroop effect: location as a contextual cue.

The Stroop effect has been shown to depend on the relative proportion of congruent and incongruent trials. This effect is commonly attributed to experiment-wide word-reading strategies that change as a function of proportion congruent. Recently, Jacoby, Lindsay, and Hessels (2003) reported an item-specific proportion congruent effect that cannot be due to these strategies and instead may reflect rapid, stimulus driven control over word-reading processes. However, an item-specific proportion congruent effect may also reflect learned associations between color word identities and responses. In two experiments, we demonstrate a context-specific proportion congruent effect that cannot be explained by such word-response associations. Our results suggest that processes other than learning of word-response associations can produce contextual control over Stroop interference.

Cues↗
PubMed1989

[The effects of conscious and subconscious processing of hostility- or friendliness-related words on the personality impression of others].

Four experiments were conducted to investigate how the prior processing of trait relevant information influenced upon the impression formation. Twenty university students participated in each experiment. First subjects performed a cognitive task in which they processed hostility (Exp. I, II) or friendliness (Exp. III, IV) related words, consciously (Exp. I, III) or subconsciously (Exp. II, IV). In another ostensibly unrelated task, subjects rated a stimulus person on several trait scales based on an ambiguous behavioral description, regarding to hostility (Exp. I, II) or friendliness (Exp. III, IV). It was shown that the more hostility words subjects processed either consciously or subconsciously, the more extreme and negative ratings they yielded. As for friendliness words, however, such effects were found only when they were subconsciously processed, not when they were consciously processed. It was argued that conscious processing was affected by positiveness or negativeness of trait words, but subconscious processing was not.

Adult↗
PubMed2005

Neurophysiological signs of rapidly emerging visual expertise for symbol strings.

The current study examined whether the repeated visual presentation of novel, meaningless symbol strings triggers rapid changes in event related potentials (ERP). Adult participants performed three versions of a word and symbol string repetition detection task in the same experimental session. Analyses focussed on the occipito-temporal N1 (approximately 150 ms) known to reflect early word-specific processing and stimulus categorisation. While the N1 to words did not change, the occipito-temporal negativity to symbol strings increased over runs and converged with the word N1. Later (approximately 220 ms) more positive occipito-temporal amplitudes to repeated words in the third compared to the first run implied a repetition priming effect. This suggests that symbol string processing changed over time due to visual learning and increased perceptual expertise.

Adult↗
PubMed2006

Developmental and skill effects on the neural correlates of semantic processing to visually presented words.

Functional magnetic resonance imaging (fMRI) was used to explore the neural correlates of semantic judgments to visual words in a group of 9- to 15-year-old children. Subjects were asked to indicate if word pairs were related in meaning. Consistent with previous findings in adults, children showed activation in bilateral inferior frontal gyri (Brodmann area [BA] 47, 45) and left middle temporal gyrus (BA 21). Words with strong semantic association elicited significantly greater activation in bilateral inferior parietal lobules (BA 40), suggesting stronger integration of highly related semantic features. By contrast, words with weak semantic association elicited greater activation in left inferior frontal gyrus (BA 45) and middle temporal gyrus (BA 21), suggesting more difficult feature search and more extensive access to semantic representations. We also examined whether age and skill explained unique variance in the patterns of activation. Increasing age was correlated with greater activation in left middle temporal gyrus (BA 21) and inferior parietal lobule (BA 40), suggesting that older children have more elaborated semantic representations and more complete semantic integration processes, respectively. Decreasing age was correlated with activation in right superior temporal gyrus (BA 22) and decreasing accuracy was correlated with activation in right middle temporal gyrus (BA 21), suggesting the engagement of ancillary systems in the right hemisphere for younger and lower-skill children.

Adolescent↗
PubMed1987

Information-processing correlates of computer-assisted word learning by mentally retarded students.

Information-processing correlates of computer-assisted word learning by moderately and severely mentally retarded students were identified. Nineteen subjects completed 10, 15-minute computer-assisted instruction sessions and seven basic cognitive tasks measuring simple learning, choice reaction time, relearning, probed recall, stimulus discrimination, tachistoscopic threshold, and recognition memory. Stimulus discrimination, probed recall, and simple learning were significantly related to word learning. Results suggest that instruction should be modified to accommodate individual differences in these abilities.

Adolescent↗
PubMed1997

Brain wave recognition of words.

Electrical and magnetic brain waves of seven subjects under three experimental conditions were recorded for the purpose of recognizing which one of seven words was processed. The analysis consisted of averaging over trials to create prototypes and test samples, to both of which Fourier transforms were applied, followed by filtering and an inverse transformation to the time domain. The filters used were optimal predictive filters, selected for each subject and condition. Recognition rates, based on a least-squares criterion, varied widely, but all but one of 24 were significantly different from chance. The two best were above 90%. These results show that brain waves carry substantial information about the word being processed under experimental conditions of conscious awareness.

Brain↗
PubMed1999

The neural correlates of verb and noun processing. A PET study.

The hypothesis that categorical information, distinguishing among word classes, such as nouns, verbs, etc., is an organizational principle of lexical knowledge in the brain, is supported by the observation of aphasic subjects who are selectively impaired in the processing of nouns and verbs. The study of lesion location in these patients has suggested that the left temporal lobe plays a crucial role in processing nouns, while the left frontal lobe is necessary for verbs. To delineate the brain areas involved in the processing of different word classes, we used PET to measure regional cerebral activity during tasks requiring reading of concrete and abstract nouns and verbs for lexical decision. These tasks activated an extensive network of brain areas, mostly in the left frontal and temporal cortex, which represents the neural correlate of single word processing. Some left hemispheric areas, including the dorsolateral frontal and lateral temporal cortex, were activated only by verbs, while there were no brain areas more active in response to nouns. Furthermore, the comparison of abstract and concrete words indicated that abstract word processing was associated with selective activations (right temporal pole and amygdala, bilateral inferior frontal cortex), while no brain areas were more active in response to concrete words. There were no significant interaction effects between word class and concreteness. Taken together, these findings are compatible with the view that lexical-semantic processing of words is mediated by an extensive, predominantly left hemispheric network of brain structures. Additional brain activations appear to be related to specific semantic content, or, in the case of verbs, may be associated with the automatic access of syntactic information.

Adult↗
PubMed1994

Computational modeling and elementary process analysis in visual word recognition.

An attempt is made to isolate the assumptions that make a connectionist approach to visual word recognition distinctive. These include the commitment to distributed representations, the claim that there is no distinction between lexical and nonlexical systems in the naming task, and the claim that it is possible to map from orthography to meaning without using localized representations. It is argued that merely demonstrating that a network model can perform these tasks is not sufficient and that a detailed theory of how the network performs its tasks must accompany the simulation, because a simulation is not equivalent to an explanation. It is argued that further progress requires detailed modeling and experimental study of the elementary processes assumed to be involved in networks and that it is premature to dismiss alternative models of lexical access such as serial search models.

Humans↗