Oral reading in dementia

Reading has been thought to consist of three main processing components: the orthographic, phonological, and semantic lexicons. In traditional psycholinguistic models, these components have been treated independently such that the selective dysfunction of one does not necessarily imply the breakdown of another. Recently, it has been proposed that a word's semantic representation is essential to oral reading such that a disturbance within the semantic lexicon will disrupt processing within the orthographic and/or phonological lexicons. From this view, semantic deterioration should lead to fragmentation of the other systems contributing to reading, resulting in a specific pattern of errors during oral reading. This would include (1) a larger than normal advantage for reading words with regular spelling-to-sound correspondence over words with exception spelling, as well as the production of "regularization errors" when reading exception words; and (2) a smaller than normal difference between reading real words and pronounceable nonwords, or pseudowords (PW's). We found that patients with Semantic Dementia generally conformed to these hypothesized patterns of reading difficulty. Despite the presence of a semantic impairment, however, patients with Alzheimer's Disease, Frontotemporal Dementia, and Progressive Non-Fluent Aphasia did not demonstrate these patterns of reading difficulty. Our findings suggest that not all semantic impairments invariably lead to the disruption of the orthographic and phonological lexicons.     

The role of phonological recoding in orthographic learning

The objective of this research was to explore whether orthographic learning occurs as a result of phonological recoding, as expected from the self-teaching hypothesis. The participants were 32 fourth- and fifth-graders (mean age = 10 years 0 months, SD = 7 months) who performed lexical decisions for monosyllabic real words and pseudowords under two matched experimental conditions: a read aloud condition, wherein items were named prior to lexical decision to promote phonological recoding, and a concurrent articulation condition, presumed to attenuate phonological recoding. Later, orthographic learning of the pseudowords was evaluated using orthographic choice, spelling, and naming tasks. Consistent with the self-teaching hypothesis, targets learned with phonological recoding in the read aloud condition yielded greater orthographic learning than those learned with concurrent articulation. The research confirms the critical nature of phonological recoding in the development of visual word recognition skills and an orthographic lexicon.     

Semantic and phonological influences on visual word learning in a transparent language

Orthographic representations of words are indispensable for reading fluency. The ways in which these representations are developed and their resistance to decay are hotly debated topics. The aim of this study was to investigate the influence of semantic and phonological representations on the formation of orthographic representations in a transparent orthography. In order to achieve this objective, an experiment with three conditions was carried out. In the first condition, a group of university students were asked to repeatedly read 10 new words after semantic and phonological training, in the second condition another group of participants read the new words after phonological training, and in the third condition participants read without previous training. Finally, a follow-up session was performed to test the resistance to decay of the orthographic representations. The results showed that participants who had received semantic training formed the representations faster than participants in the other conditions, as indicated by the decrease in length effect. These results indicate the important role of previous knowledge when people face new written words. A month later these orthographic representations still remained in the lexicon of the participants.     

The effect of orthographic structure on word recognition in a visual search task

The effect of the orthographic structure of the stimulus field on the visual search performance of third graders (8-8 years), sixth graders (11-7 years) and adults was investigated in three experiments. In Experiment 1, where the predesignated target was one word, subjects of all ages searched equally fast through fields consisting of words, pseudowords, and nonwords. In contrast, subjects of all ages displayed effects of orthographic structure when searching for instances of a semantic category (Experiment 2) or for three words (Experiment 3). Subjects searched faster through nonwords than through pseudowords and faster through pseudowords than through words. The use of orthographic structure to facilitate search did not increase with age, suggesting that children of the youngest age group were already making maximal use of intraword redundancy.     

The effects of phonological similarity on the semantic categorisation of pictorial and lexical stimuli: evidence from continuous behavioural measures

Behavioural and neuroimaging studies provide evidence of automatic activation of phonology (e.g., covert speech) during the recognition of lexical stimuli. Implicit processing of phonological information was investigated in a kinematic study of semantic categorisation of pictures (session A) or words (session B). Participants clicked one of two items (target and distractor) based on their semantic congruency (artefact or natural) with a cued-word. Phonological similarity between cued-word and distractor was varied. The presence of the phonological distractor produced trajectories with greater curvature towards the competing semantic category than did the presence of a distractor not phonologically related. This suggests that the semantic categorisation of pictorial and lexical stimuli is influenced by the automatic activation of phonological information. Trajectories’ curvature reveals competition between partially activated phonological and semantic representations suggesting that phonological codes involved in linguistic processing influence the dynamic competition underlying the semantic categorisation of lexical and pictorial.     

Phonological and semantic information in adults' orthographic learning

A training paradigm was used to assess the early stages of the acquisition of novel letter strings in adults. Provision of either phonological or semantic information during training improved spelling recognition (Experiment 1). Manipulation of the processing required during training (phonological, semantic, or both) produced no consistent effects on spelling when both phonology and meaning were provided (Experiment 2). An advantage of phonological over orthographic processing on spelling recognition and cued recall was found when meaning was provided during training but phonology was not (Experiment 3). The experiments support the role of phonological information in early learning of orthography, but additional research is required to clarify when and how semantic information supports the formation of new orthographic representations.     

What exactly is a yait anyway: The role of semantics in orthographic learning

This study investigated whether semantic information presented along with novel printed nonwords facilitates orthographic learning and examined predictors of individual differences in this important literacy skill. A sample of 35 fourth graders was tested on a variety of language and literacy tests, and participants were then exposed to 10 target nonwords, 5 of which were presented with semantic information. Children were tested 1 and 4 days later on their ability to correctly recognize and spell the target nonwords. Results revealed a significant main effect on the recognition task, where items presented with semantic information were identified correctly more often than were words presented in isolation. No significant effect of training condition was found for the spelling posttests. Furthermore, multiple regression analyses revealed that both phonological and semantic factors were significant predictors of orthographic learning. The findings support the view that orthographic learning, as measured through visual recognition, involves the integration of phonological, orthographic, and semantic representations.     

Orthography and phonology in reading Japanese kanji words: Evidence from the semantic decision task with homophones

Correspondences between spelling and sound for Japanese kanji are complex and deep. The meaning of kanji words has generally been assumed to be accessed directly from orthography without phonological mediation. Experiment 1, however, replicated the findings of Van Orden (1987) that subjects made more false-positive errors on homophone foils than they did on nonhomophone controls in a semantic decision task, although they did so only when the foils were orthographically similar to the correct exemplars, which indicates both orthographic and phonological activations of meaning. Experiment 2 showed the same results when subjects were not required to pronounce the target words after semantic decisions, which indicates automatic phonological activation of kanji words. In Experiment 3, under pattern-masking conditions, this homophony effect was reduced but remained on errors, and the orthographic-similarity effect remained strong on both homophone and nonhomophone foils. These results suggest that both orthography and phonology play an important role in the comprehension of kanji words.     

The N400 and the fourth grade shift

While behavioral and educational data characterize a fourth grade shift in reading development, neuroscience evidence is relatively lacking. We used the N400 component of the event‐related potential waveform to investigate the development of single word processing across the upper elementary years, in comparison to adult readers. We presented third graders, fourth graders, fifth graders, and college students with a well‐controlled list of real words, pseudowords, letter strings, false font strings, and animal name targets. Words and pseudowords elicited similar N400s across groups. False font strings elicited N400s similar to words and letter strings in the three groups of children, but not in college students. The pattern of findings suggests relatively adult‐like semantic and phonological processing by third grade, but a long developmental time course, beyond fifth grade, for orthographic processing in this context. Thus, the amplitude of the N400 elicited by various word‐like stimuli does not reflect some sort of shift or discontinuity in word processing around the fourth grade. However, the results do suggest different developmental time courses for the processes that contribute to automatic single word reading and the integrative N400.     

The influence of consistency, frequency, and semantics on learning to read: an artificial orthography paradigm

Two experiments explored learning, generalization, and the influence of semantics on orthographic processing in an artificial language. In Experiment 1, 16 adults learned to read 36 novel words written in novel characters. Posttraining, participants discriminated trained from untrained items and generalized to novel items, demonstrating extraction of individual character sounds. Frequency and consistency effects in learning and generalization showed that participants were sensitive to the statistics of their learning environment. In Experiment 2, 32 participants were preexposed to the sounds of all items (lexical phonology) and to novel definitions for half of these items (semantics). Preexposure to either lexical phonology or semantics boosted the early stages of orthographic learning relative to Experiment 1. By the end of training, facilitation was restricted to the semantic condition and to items containing low-frequency inconsistent vowels. Preexposure reduced generalization, suggesting that enhanced item-specific learning was achieved at the expense of character-sound abstraction. The authors' novel paradigm provides a new tool to explore orthographic learning. Although the present findings support the idea that semantic knowledge supports word reading processes, they also suggest that item-specific phonological knowledge is important in the early stages of learning to read.     

The acronym superiority effect

The visual world is replete with noisy, continuous, perceptually variant linguistic information, which fluent readers rapidly translate from percept to meaning. What are the properties the language comprehension system uses as cues to initiate lexical/semantic access in response to some, but not all, orthographic strings? In the behavioral, electromagnetic, and neuropsychological literatures, orthographic regularity and familiarity have been identified as critical factors. Here, we present a study in the Reicher—Wheeler tradition that manipulates these two properties independently through the use of four stimulus categories: familiar and orthographically regular words, unfamiliar but regular pseudowords, unfamiliar illegal strings, and familiar but orthographically illegal acronyms. We find that, like letters in words and pseudowords, letters in acronyms enjoy an identification benefit relative to similarly illegal, but unfamiliar strings. This supports theories of visual word recognition in which familiarity, rather than orthographic regularity, plays a critical role in gating processing.     

Connectivity among semantic associates: an fMRI study of semantic priming

Semantic priming refers to a reduction in the reaction time to identify or make a judgment about a stimulus that has been immediately preceded by a semantically related word or picture and is thought to result from a partial overlap in the semantic associates of the two words. A semantic priming lexical decision task using spoken words was presented in event-related fMRI and behavioral paradigms. Word pairs varied in terms of semantic relatedness and the connectivity between associates. Thirteen right-handed subjects underwent fMRI imaging and 10 additional subjects were tested in a behavioral version of the semantic priming task. It was hypothesized priming would be greatest, reaction time fastest, and cortical activation reduced the most for related word pairs of high connectivity, followed by related word pairs of low connectivity, and then by unrelated word pairs. Behavioral and fMRI results confirmed these predictions. fMRI activity located primarily in bilateral posterior superior and middle temporal regions showed modulation by connectivity and relatedness. The results suggest that these regions are involved in semantic processing.     

Brain potentials as indices of orthographic and phonological interaction during word matching

The interaction between orthographic and phonological codes in a same-different judgment task was studied by requiring subjects to decide if two visually presented words either looked alike or rhymed. Word pairs were selected from four different lists. Words rhymed and looked alike, rhymed but did not look alike, looked alike but did not rhyme, or neither looked alike nor rhymed. Reaction time and percent error increased whenever there was a conflict between the orthography and phonology of the words. The N200 component of the event-related brain potential (ERP) indicated that subjects were capable of detecting phonological differences between words within 260 ms from the presentation of a word pair. The amplitude of the N200s also varied with the degree of mismatch between words. N200s were largest when both the orthography and phonology mismatched, of intermediate amplitude when either orthography or phonology mismatched, and smallest when both orthography and phonology matched. P300 latency was consistent with reaction time, increasing whenever there was a conflict between the two codes. Taken together, behavioral measures and the ERP data suggest that the extraction of the orthographic and phonological aspects of words occurs early in the information processing sequence.     

Better the DVL you know: acronyms reveal the contribution of familiarity to single-word reading

Current theories of reading are divided between dual-route accounts, which propose that separable processes subserve word recognition for orthographically regular and irregular strings, and connectionist models, which propose a single mechanism mapping form to meaning. These theories make distinct predictions about the processing of acronyms, which can be orthographically illegal and yet familiar, as compared with the processing of pseudowords, which are regular but unfamiliar. This study examined whether acronyms are processed like pseudowords and words. Event-related potentials (ERPs) were recorded as subjects viewed familiar and unfamiliar acronyms, words, pseudowords, illegal strings, and--as the targets of the substantive behavioral task--proper names. Familiar acronyms elicited repetition effects on the N400 component, a functionally specific index of semantic activation processes; repetition effects for familiar acronyms were similar in magnitude, timing, and scalp distribution to those for words and pseudowords. The similarity of the brain response to familiar--but--illegal and unfamiliar--but--legal classes of stimuli is inconsistent with predictions of dual-route models of reading.     

语言加工性别差异的神经机制

神经成像技术为语言加工的性别差异研究提供了新的手段和证据。研究者们从语言加工的词汇、句子、篇章理解和语言学习、再认和记忆等层面进行了大量的男女性脑功能差异研究。同时, 语言加工的性别差异也从脑结构–生理基础差异方面进行了探讨, 主要包括了灰质分布差异、胼胝体大小差异和荷尔蒙的影响。然而, 语言加工是否有性别差异还存在争议, 不同的研究者从加工时间要求、陈述性记忆差异和方法学考虑等方面对分歧做出了解释。     

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.     

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.     

Does phonological recoding occur during silent reading, and is it necessary for orthographic learning?

Two studies were conducted to test the central claim of the self-teaching hypothesis (i.e., phonological recoding is necessary for orthographic learning) in silent reading. The first study aimed to demonstrate the use of phonological recoding during silent reading. Texts containing pseudowords were read silently or aloud. Two days later, target spellings were recognized more often than their homophone spellings. In both reading conditions, homophone alternatives were named faster than nonexposed pseudowords, suggesting that phonological recoding had occurred. The second study aimed to suppress phonological recoding to demonstrate its necessity for orthographic learning. Lexical decisions were performed in a standard condition, with concurrent articulation, or with tapping. One day later, target spellings were recognized less often after lexical decisions with concurrent articulation. Target and homophone naming speed was not affected by lexical decision condition. The results support the use of phonological recoding during silent reading and specify its role in orthographic learning.     

Large-Scale Modeling of Wordform Learning and Representation

The forms of words as they appear in text and speech are central to theories and models of lexical processing. Nonetheless, current methods for simulating their learning and representation fail to approach the scale and heterogeneity of real wordform lexicons. A connectionist architecture termed the sequence encoder is used to learn nearly 75,000 wordform representations through exposure to strings of stress-marked phonemes or letters. First, the mechanisms and efficacy of the sequence encoder are demonstrated and shown to overcome problems with traditional slot-based codes. Then, two large-scale simulations are reported that learned to represent lexicons of either phonological or orthographic wordforms. In doing so, the models learned the statistics of their lexicons as shown by better processing of well-formed pseudowords as opposed to ill-formed (scrambled) pseudowords, and by accounting for variance in well-formedness ratings. It is discussed how the sequence encoder may be integrated into broader models of lexical processing.