Hemisphere dynamics in lexical access: automatic and controlled priming

Hemisphere differences in lexical processing may be due to asymmetry in the organization of lexical information, in procedures used to access the lexicon, or both. Six lateralized lexical decision experiments employed various types of priming to distinguish among these possibilities. In three controlled (high probability) priming experiments, prime words could be used as lexical access clues. Larger priming was obtained for orthographically similar stimuli (BEAK-BEAR) when presented to the left visual field (LVF). Controlled priming based on phonological relatedness (JUICE-MOOSE) was equally effective in either visual field (VF). Semantic similarity (INCH-YARD) produced larger priming for right visual field (RVF) stimuli. These results suggest that the hemispheres may utilize different information to achieve lexical access. Spread of activation through the lexicon was measured in complementary automatic (low probability) priming experiments. Priming was restricted to LVF stimuli for orthographically similar words, while priming for phonologically related stimuli was only obtained in the RVF. Automatic semantic priming was present bilaterally, but was larger in the LVF. These results imply hemisphere differences in lexical organization, with orthographic and semantic relationships available to the right hemisphere, and phonological and semantic relations available to the left hemisphere. Support was obtained for hemisphere asymmetries in both lexical organization and directed lexical processing.     

Locus of semantic interference in picture-word interference tasks

Picture#x2014;word interference studies typically show that semantically related distractor words embedded within a picture slow picture-naming responses, relative to unrelated ones. This semantic interference effect is commonly interpreted as arising from the competition of lexical#x2014;semantic (e.g., Schriefers, Meyer, & Levelt, 1990) or lexical#x2014;phonological (e.g., Starreveld & La Heij, 1996) codes. The experiment reported here tests a crucial assumption shared by these accounts#x2014;namely, that the effect reflects a lexical, rather than a nonverbal, conceptual conflict. Pictures were named while participants attempted to ignore embedded distractors that were in either verbal or pictorial format. The presence of both words and pictures substantially interfered with naming responses, but only words, not pictures, were found to induce semantic interference. These findings support the claim that for semantic interference to arise, both target picture and distractor have to be lexicalized. Consequently, a general conceptual locus of the effect can be excluded, and the claim that semantic interference is based on a lexical conflict is confirmed.     

Semantic and phonological information flow in the production lexicon

When speakers produce words, lexical access proceeds through semantic and phonological levels of processing. If phonological processing begins based on partial semantic information, processing is cascaded; otherwise, it is discrete. In standard models of lexical access, semantically processed words exert phonological effects only if processing is cascaded. In 3 experiments, speakers named pictures of objects with homophone names (ball), while auditory distractor words were heard beginning 150 ms prior to picture onset. Distractors speeded picture naming (compared with controls) only when related to the nondepicted meaning of the picture (e.g., dance), exhibiting an early phonological effect, thereby supporting the cascaded prediction. Distractors slowed picture naming when categorically (e.g., frisbee) related to the depicted picture meaning, but not when associatively (e.g., game) related to it. An interactive activation model is presented.     

汉语词汇产生中词汇选择和音韵编码之间的交互作用

采取图画－词汇干扰实验范式,探索汉语单音节词汇产生中词汇选择和音韵编码之间的交互作用。实验一探测目标图画语义相关项的语音激活,观察到了非目标项的语音激活。实验二探测目标图画语义相关项的字形激活,未发现非目标项的字形激活。在改进实验条件的基础上,实验三验证实验一和二,并探测目标图画字形相关项的语音激活以及语音相关项的字形激活,结果未探测到语义相关项的字形或语音激活、语音相关项的字形激活,只发现了字形相关项的语音激活。实验一至三的结果表明汉语词汇产生中存在目标字字形相关项的语音激活,但不存在从音韵编码阶段至词汇选择阶段的激活反馈。综合上述结果,从是否存在多重的字形或语音激活,以及是否存在从音韵编码至词汇选择的反馈两个方面进行了讨论。研究结果倾向于支持词汇产生中层叠式理论的观点     

Auditory context effects in picture naming investigated with event-related fMRI

Naming an object entails a number of processing stages, including retrieval of a target lexical concept and encoding of its phonological word form. We investigated these stages using the picture-word interference task in an fMRI experiment. Participants named target pictures in the presence of auditorily presented semantically related, phonologically related, or unrelated distractor words or in isolation. We observed BOLD signal changes in left-hemisphere regions associated with lexical-conceptual and phonological processing, including the midto-posterior lateral temporal cortex. However, these BOLD responses manifested as signal reductions for all distractor conditions relative to naming alone. Compared with unrelated words, phonologically related distractors showed further signal reductions, whereas only the pars orbitalis of the left inferior frontal cortex showed a selective reduction in response in the semantic condition. We interpret these findings as indicating that the word forms of lexical competitors are phonologically encoded and that competition during lexical selection is reduced by phonologically related distractors. Since the extended nature of auditory presentation requires a large portion of a word to be presented before its meaning is accessed, we attribute the BOLD signal reductions observed for semantically related and unrelated words to lateral inhibition mechanisms engaged after target name selection has occurred, as has been proposed in some production models.     

Orthographic and phonological activation in recognizing Chinese characters

This paper is a contribution to the study of whether visual contact with lexical units in any writing system necessarily arouses their corresponding phonological information. In two experiments it was investigated whether phonological information is automatically activated during the semantic processing of Chinese characters. In these experiments, both using a semantic-categorization task, subjects produced the same proportion of false positive categorization errors and showed the same decision latencies on homophone foils and their non-homophonic controls, thus indicating that phonological information does not seem to affect the semantic task. Experiment 2 further revealed that subjects made more errors and produced longer response times on graphemically similar foils than on the corresponding controls. The absence of phonological effects and the presence of clear effects of visual similarity for Chinese characters in semantic tasks can be taken to indicate that phonological information may not be automatically activated during the processing of meanings of Chinese characters. The present results also cast serious doubts on the hypothesis that phonological activation is a universal principle of lexical processing.     

再探汉字加工中语音、语义激活的相对时间进程

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

Representation and competition in the perception of spoken words

We present data from four experiments using cross-modal priming to examine the effects of competitor environment on lexical activation during the time course of the perception of a spoken word. The research is conducted from the perspective of a distributed model of speech perception and lexical representation, which focuses on activation at the level of lexical content. In this model, the strength of competition between simultaneously active lexical items depends on the degree of coherence between their distributed semantic and phonological representations. Consistent with this model, interference effects are more complete when the purely semantic aspects of these coactive representations are probed (using semantic priming) than when phonological aspects are probed as well (using repetition priming).     

延迟命名任务中图词干扰效应的眼动研究

采用图-词分离呈现及眼动技术探讨在延时命名条件下图-词干扰效应发生的位置。结果发现：（1）延时命名图片时,仍出现图-词干扰效应和频率效应;（2）与命名干扰词相比,命名图片时图片的回视率高,注视时间长;（3）图片的注视时间也出现频率效应和图-词干扰效应。这说明即使在延时命名图片的条件下,目标词汇仍需要再次激活,频率效应和图-词干扰效应是发生在词汇化过程中,反驳反应排除理论的图-词干扰反应选择阶段的观点,支持了词汇化选择竞争的理论。     

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

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

Investigating the interplay between semantic and phonological distractor effects in picture naming

In this paper, we investigate the interplay between phonological facilitation and semantic interference effects in picture naming. We use a double distractor variant of the classic picture-word interference paradigm to investigate whether the reported interaction between these effects is dependent on the two types of related information being presented by the same distractor word or not. While prior studies using single mixed distractors such as pigeon for the target PIG have reported an interaction between phonological facilitation and semantic interference, we find additivity when the two types of related information come from two different distractor words. Possible implications of this result for how activation is transmitted within the speech production system are discussed.     

The relative time course of semantic and phonological activation in reading Chinese

The relative time course of semantic and phonological activation was investigated in the context of whether phonology mediates access to lexical representations in reading Chinese. Compound words (Experiment 1) and single-character words (Experiments 2 and 3) were preceded by semantic and phonological primes. Strong semantic priming effects were found at both short (57 ms) and long (200 ms) stimulus onset asynchrony (SOA), but phonological effects were either absent in lexical decision (Experiment 1), were present only at the longer SOA in character decision (Experiment 2) or were equally strong as semantic effects in naming (Experiment 3). Experiment 4 revealed facilitatory or inhibitory effects, depending on SOA, in phonological judgments to character pairs that were not phonologically but semantically related. It was concluded that, in reading Chinese, semantic information in the lexicon is activated at least as early and just as strongly as phonological information.     

Phonology in the Lexical Processing of Chinese: Priming Tone Neighbors

Using both visual-visual and auditory-visual priming lexical decision tasks, this study investigated phonological processing in reading logographic Chinese. Compound words sharing segmental templates but differing in lexical tones were used as primes and targets while their relative frequency was manipulated. It was found that tone neighbours did not prime each other significantly and the SOA of 100 msec in visual-visual priming. When the SOA was increased to 357 msec, or when primes were presented auditorily, the processing of target words was significantly delayed by their tone neighbours. Larger inhibitory effects were observed for low frequency targets with high frequency primes. It was argued that although phonological information is automatically activated and this activation affects access to semantics in reading Chinese,phonological mediation is not the only or the main ~urce of constraints on semantic activation.     

The role of lexical competition and acoustic-phonetic structure in lexical processing: evidence from normal subjects and aphasic patients

This study examined the effects that the acoustic-phonetic structure of a stimulus exerts on the processes by which lexical candidates compete for activation. An auditory lexical decision paradigm was used to investigate whether shortening the VOT of an initial voiceless stop consonant in a real word results in the activation of the lexical-semantic network of its voiced competitor, i.e., does acoustically modified time prime penny via dime. Results for normal subjects showed semantic priming for related pairs and mediated priming for voiced competitors, consistent with cascade models of language processing allowing for interaction between phonological and semantic levels of processing. Although Broca's aphasics showed semantic priming (dime primed penny), they failed to show priming in the context of a lexical competitor. These results are consistent with the hypothesis that these patients have a lexical processing deficit characterized by an overall reduction in lexical activation.     

Individual differences in mature readers in reading, spelling, and grapheme-phoneme conversion

Individual differences in word recognition, spelling, verbal reasoning, frequency of print exposure, phonological skills, Gestalt processing and semantic processing were examined in 110 university undergraduates. Most reading and phonological tasks involved making sequences of lexical decisions through lists of common stimuli within set time limits. The test measures were percentages correct adjusting for chance. The main findings were as follows: First, there is a substantial “Matthew effect” in that good readers were also good at spelling, good at handling the meaning of words, and appeared to have had the most print exposure. Second, phonological skills appear to be independent of lexical skills. Furthermore, within these phonological skills there appear to be two components, one that is automatic, and one that is more of a conscious operation.     

The neurobiology of adaptive learning in reading: A contrast of different training conditions

fMRI was used to investigate the separate influences of orthographic, phonological, and semantic processing on the ability to learn new words and the cortical circuitry recruited to subsequently read those words. In a behavioral session, subjects acquired familiarity for three sets of pseudowords, attending to orthographic, phonological, or (learned) semantic features. Transfer effects were measured in an event-related fMRI session as the subjects named trained pseudowords, untrained pseudowords, and real words. Behaviorally, phonological and semantic training resulted in better learning than did orthographic training. Neurobiologically, orthographic training did not modulate activation in the main reading regions. Phonological and semantic training yielded equivalent behavioral facilitation but distinct functional activation patterns, suggesting that the learning resulting from these two training conditions was driven by different underlying processes. The findings indicate that the putative ventral visual word form area is sensitive to the phonological structure of words, with phonologically analytic processing contributing to the specialization of this region.     

How does the provision of semantic information influence the lexicalization of new spoken words?

The integration of a novel spoken word with existing lexical items can proceed within 24 hours of learning its phonological form. However, previous studies have reported that lexical integration of new spoken words can be delayed if semantic information is provided during learning. One possibility is that this delay in lexical integration reflects reduced phonological processing during learning as a consequence of the need to learn the semantic associations. In the current study, adult participants learnt novel words via a phoneme monitoring task, in which half of the words were associated with a picture referent, and half were phonological forms only. Critically, participants were instructed to learn the forms of the novel words, with no explicit goal to learn the word–picture mappings. Results revealed significant lexical competition effects emerging one week after consolidation, which were equivalent for the picture-present and form-only conditions. Tests of declarative memory and shadowing showed equivalent performance for picture-present and form-only words, despite participants showing good knowledge of the picture associations immediately after learning. These data support the contention that provided phonological information is recruited sufficiently well during learning, the provision of semantic information does not slow the time-course of lexical integration.     

Individual differences in mature readers in reading,spelling, and grapheme-phoneme conversion

Individual differences in word recognition, spelling, verbal reasoning, frequency of print exposure, phonological skills, Gestalt processing and semantic processing were examined in 110 university undergraduates. Most reading and phonological tasks involved making sequences of lexical decisions through lists of common stimuli within set time limits. The test measures were percentages correct adjusting for chance. The main findings were as follows: First, there is a substantial “Matthew effect” in that good readers were also good at spelling, good at handling the meaning of words, and appeared to have had the most print exposure. Second, phonological skills appear to be independent of lexical skills. Furthermore, within these phonological skills there appear to be two components, one that is automatic, and one that is more of a conscious operation.     

Reduced short-term memory capacity in Alzheimer's disease: The role of phonological,lexical, and semantic processing

Individuals with Alzheimer's disease (AD) are often reported to have reduced verbal short-term memory capacity, typically attributed to their attention/executive deficits. However, these individuals also tend to show progressive impairment of semantic, lexical, and phonological processing which may underlie their low short-term memory capacity. The goals of this study were to assess the contribution of each level of representation (phonological, lexical, and semantic) to immediate serial recall performance in 18 individuals with AD, and to examine how these linguistic effects on short-term memory were modulated by their reduced capacity to manipulate information in short-term memory associated with executive dysfunction. Results showed that individuals with AD had difficulty recalling items that relied on phonological representations, which led to increased lexicality effects relative to the control group. This finding suggests that patients have a greater reliance on lexical/semantic information than controls, possibly to make up for deficits in retention and processing of phonological material. This lexical/semantic effect was not found to be significantly correlated with patients’ capacity to manipulate verbal material in short-term memory, indicating that language processing and executive deficits may independently contribute to reducing verbal short-term memory capacity in AD.     

Semantic priming is affected by real-time phonological competition: Evidence for continuous cascading systems

Lexical-semantic access is affected by the phonological structure of the lexicon. What is less clear is whether such effects are the result of continuous activation between lexical form and semantic processing or whether they arise from a more modular system in which the timing of accessing lexical form determines the timing of semantic activation. This study examined this issue using the visual world paradigm by investigating the time course of semantic priming as a function of the number of phonological competitors. Critical trials consisted of high or low density auditory targets (e.g., horse) and a visual display containing a target, a semantically related object (e.g., saddle), and two phonologically and semantically unrelated objects (e.g., chimney, bikini). Results showed greater magnitude of priming for semantically related objects of low than of high density words, and no differences for high and low density word targets in the time course of looks to the word semantically related to the target. This pattern of results is consistent with models of cascading activation, which predict that lexical activation has continuous effects on the level of semantic activation, with no delays in the onset of semantic activation for phonologically competing words.