Aviah Gvion

Sentence comprehension and working memory limitation in aphasia: A dissociation between semantic-syntactic and phonological reactivation

The relation between working memory (WM) limitation and sentence comprehension was assessed in Hebrew-speaking aphasics, three conduction aphasics and three agrammatics. The study compared sentences that required different types of reactivation-syntactic-semantic reactivation, in relative clauses, and word form/phonological reactivation, in sentences with reanalysis of lexical ambiguity. The effect of phonological memory load, manipulated by number of words intervening between the activation and the reactivation, on comprehension of the two sentence types was examined. The findings were that agrammatic aphasics failed in the comprehension of object relatives but not on subject relatives irrespective of their antecedent-gap distance. Conduction aphasics, on the other hand, who showed severe WM limitation, comprehended well all types of relative clauses and were unaffected by antecedent-gap distance. The conduction aphasics failed to understand the sentences that required phonological reactivation when the phonological distance was long. These results suggest that the type of reactivation required by the sentence, as well as the type of memory overload are crucial in determining the effect of WM limitation on sentence comprehension.

Letter Position Dyslexia

Many word-reading models assume that the early stages of reading involve a separate process of letter position encoding. However, neuropsychological evidence for the existence and selectivity of this function has been rather indirect, coming mainly from position preservation in migrations between words in attentional dyslexia, and from nonselective reading deficits. No pure demonstration of selective impairment of letter position function has yet been made. In this paper two Hebrew-speaking acquired dyslexic patients with occipito-parietal lesions are presented who suffer from a highly selective deficit to letter position encoding. As a result of this deficit, they predominantly make errors of letter migration within words (such as reading “broad” for “board”) in a wide variety of tasks: oral reading, lexical decision, same-different decision, and letter location. The deficit is specific to orthographic material, and is manifested mainly in medial letter positions. The implications of the findings to models of reading and attention are discussed.

Letter form as a constraint for errors in neglect dyslexia and letter position dyslexia

Does letter-form constrain errors in peripheral dyslexia? In Hebrew, 5 of the 22 letters have two different letter forms, one is used only when the letter occurs in word-final position, the other form is used in initial and middle positions. Is the information on final-forms encoded in the letter identity information and used for word identification, or is it discarded? The current research explored this question through the effect of final vs. non final letter form on the error pattern in neglect dyslexia (neglexia) and letter position dyslexia (LPD). Left word-based neglexia results in errors of omission, substitution and addition of letters in the left side of words, which in Hebrew is the end of the word. We examined whether final letter form blocks the addition of letters to the end of the word and whether omissions of letters after letters in non-final form are avoided. The predominant error type in LPD is migration of letters within words. We tested whether migrations also occur when they cause form change of either final-form letters that move to middle position or middle-form letters that move to final position. These questions were assessed in both acquired and developmental neglexia and LPD. The results indicated a strong effect of final letter-form on acquired neglexia and on acquired and developmental LPD, which almost completely prevented form-changing errors. This effect was not found in developmental neglexia, where words that end in final-form letters were actually more impaired than other words, probably because final-form letters appear only on the neglected side of the word for Hebrew-reading children with left developmental neglexia. These data show that early visuo-orthographic analysis is sensitive to final letter form and that final letter form constrains errors in peripheral dyslexia.

Does phonological working memory impairment affect sentence comprehension? A study of conduction aphasia

Background: The nature of the relation between phonological working memory and sentence comprehension is still an open question. This question has theoretical implications with respect to the existence of various working memory resources and their involvement in sentence processing. It also bears clinical implications for the language impairment of patients with phonological working memory limitation, such as individuals with conduction aphasia. Aims: This study explored whether limited phonological working memory impairs sentence comprehension in conduction aphasia. Methods & Procedures: The participants were 12 Hebrew-speaking individuals with conduction aphasia who, according to 10 recall and recognition span tasks, had limited phonological short-term memory in comparison to 296 control participants. Experiments 1 and 2 tested their comprehension of relative clauses, which require semantic-syntactic reactivation, using sentence–picture matching and plausibility judgement tasks. Experiments 3 and 4 tested phonological reactivation, using two tasks: a paraphrasing task for sentences containing an ambiguous word in which disambiguation requires re-accessing the word form of the ambiguous word, and rhyme judgement within sentences. In each task the distance between a word and its reactivation was manipulated by adding words/syllables, intervening arguments, or intervening embeddings. Outcomes & Results: Although their phonological short-term memory, and hence their phonological working memory, was very impaired, the individuals with conduction aphasia comprehended relative clauses well, even in sentences with a long distance between the antecedent and the gap. They failed to understand sentences that required phonological reactivation when the phonological distance was long. Conclusions: The theoretical implication of this study is that phonological working memory is not involved when only semantic-syntactic reactivation is required. Phonological working memory does support comprehension in very specific conditions: when phonological reactivation is required after a long phonological distance. The clinical implication of these results is that because most of the sentences in daily language input can be understood without phonological reactivation, individuals with phonological working memory impairment, such as individuals with conduction aphasia, are expected to understand sentences well, as long as they understand the meaning of the sentences and do not attempt to repeat them or encode them phonologically.

Phonological short-term memory in conduction aphasia

Background: Within cognitive neuropsychological models conduction aphasia has been conceptualised as a phonological buffer deficit. It may affect the output buffer, the input buffer, or both. The phonological output buffer is a short-term storage, responsible for the short-term maintenance of phonological units until their articulation, as well as for phonological and morphological composition. The phonological input buffer holds input strings until they are identified in the input lexicon. Thus the phonological buffers are closely related to phonological short-term memory (pSTM), and hence it is important to assess pSTM in conduction aphasia. Because the input and output buffers play different roles, impairment in each of them predicts different impairments in the patients ability to understand certain sentences, to learn new words and names, and to remember and recall lists of words and numbers for short time periods. This research was supported by a research grant from the National Institute for Psychobiology in Israel (Friedmann 2004-5-2b), by the Israel Science Foundation (grant no. 1296/06, Friedmann), and by the ARC Centre of Excellence in Cognition and its Disorders (CCD), Macquarie University. Aims: This study explored in detail pSTM in individuals with conduction aphasia, comparing individuals with input and output deficits, recall and recognition tasks, and stimuli of various types. It also tested pSTM in six age groups of healthy individuals, assessing the effect of age on various types of stimuli. This paper presents a new battery of 10 recall and recognition span tests, designed to assess pSTM in aphasia and to measure spans and effects on spans. Methods & Procedures: The participants were 14 Hebrew-speaking individuals with conduction aphasia, 12 with input or input-output phonological buffer deficit, and 2 with only output deficit, and 296 healthy individuals. Outcomes & Results: The analyses of the spans and effects on pSTM in the 10 tests indicated that all the participants with conduction aphasia had limited pSTM, significantly poorer than that of the control participants, and no semantic STM impairment. They had shorter spans, smaller length and similarity effects, and larger sentential effect than the controls. The individuals with conduction aphasia who had an impairment in the phonological input buffer showed deficit in both the recall and recognition span tasks. The individuals with the output conduction aphasia showed impairment only in the recall tasks. The healthy individuals showed age effect on span tasks involving words, but no effect of age on span tasks of nonwords. Conclusions: pSTM is impaired in conduction aphasia, and different pSTM impairments characterise different types of conduction aphasia. Output conduction aphasia causes difficulties only when verbal output is required, whereas input conduction aphasia also causes a deficit when only recognition is required. This suggests that rehearsal can take place without the phonological output buffer. Age differentially affects pSTM for words and nonwords in healthy adults: whereas the encoding of words changes, the ability to remember nonwords is unchanged.

As far as individuals with conduction aphasia understood these sentences were ungrammatical: Garden path in conduction aphasia

Background: Recent studies have indicated that working memory is not a unitary resource and that different types of working memory are used for different types of linguistic processing: syntactic, semantic, and phonological. Phonological working memory was found to support the comprehension of sentences that require re‐access to the word‐form of a word that appeared earlier in the sentence. The research was supported by a research grant from the National Institute for Psychobiology in Israel (Friedmann 2004‐5‐2b), and by the Joint German–Israeli Research Program grant (Friedmann GR‐01791). We thank Irena Botwinik‐Rotem, Tali Siloni, and Michal Biran for discussions of this study. Aims: This study explored the relation between phonological working memory and sentence comprehension by testing the comprehension of garden path sentences in individuals with conduction aphasia who have very limited phonological working memory. Our prediction was that if phonological working memory limitation hampers word‐form reactivation, only the comprehension of garden paths that require word‐form reactivation will be impaired, whereas garden paths that require only structural reanalysis will be better preserved. Methods & Procedures: Five individuals with conduction aphasia and 15 matched controls participated in working memory tests and a garden path comprehension test. The phonological working memory assessment included a battery of 10 tests, which showed that four of the individuals, who had input conduction aphasia, had very limited phonological working memory, and one individual, with output conduction aphasia, had unimpaired working memory. The comprehension study included 60 garden path sentences of three types: structural garden paths, which require only structural reanalysis, lexical garden paths, which require lexical re‐access in addition to structural reanalysis, and optional‐complement garden paths, which require re‐access to the lexical‐syntactic frame of the verb in addition to the structural reanalysis. Outcomes & Results: The main result was that the individuals with input conduction aphasia showed different degrees of impairment in different types of garden path sentences. The lexical garden paths were exceptionally hard for them, with a mere 10% correct, and significantly more difficult than the structural garden paths. The individual with output conduction aphasia whose working memory was intact comprehended the lexical garden paths similarly to the normal controls. Conclusions: These findings indicate that phonological working memory impairment only affects the comprehension of sentences that require phonological, word‐form re‐access. The type of sentence and the type of processing it requires should be taken into account when trying to predict the effect of working memory limitation on a patients ability to understand sentences. Whereas individuals with input conduction aphasia can understand complex syntactic structures well, they have considerable difficulties understanding sentences that also require re‐access to a word‐form.

A Principled Relation between Reading and Naming in Acquired and Developmental Anomia: Surface Dyslexia Following Impairment in the Phonological Output Lexicon

Lexical retrieval and reading aloud are often viewed as two separate processes. However, they are not completely separate—they share components. This study assessed the effect of an impairment in a shared component, the phonological output lexicon, on lexical retrieval and on reading aloud. Because the phonological output lexicon is part of the lexical route for reading, individuals with an impairment in this lexicon may be forced to read aloud via the sublexical route and therefore show a reading pattern that is typical of surface dyslexia. To examine the effect of phonological output lexicon deficit on reading, we tested the reading of 16 Hebrew-speaking individuals with phonological output lexicon anomia, eight with acquired anomia following brain damage and eight with developmental anomia. We established that they had a phonological output lexicon deficit according to the types of errors and the effects on their naming in a picture naming task, and excluded other deficit loci in the lexical retrieval process according to a line of tests assessing their picture and word comprehension, word and non-word repetition, and phonological working memory. After we have established that the participants have a phonological output lexicon deficit, we tested their reading. To assess their reading and type of reading impairment, we tested their reading aloud, lexical decision, and written word comprehension. We found that all of the participants with phonological output lexicon impairment showed, in addition to anomia, also the typical surface dyslexia errors in reading aloud of irregular words, words with ambiguous conversion to phonemes, and potentiophones (words like “now” that, when read via the sublexical route, can be sounded out as another word, “know”). Importantly, the participants performed normally on pseudohomophone lexical decision and on homophone/potentiophone reading comprehension, indicating spared orthographic input lexicon and spared access to it and from it to lexical semantics. This pattern was shown both by the adults with acquired anomia and by the participants with developmental anomia. These results thus suggest a principled relation between anomia and dyslexia, and point to a distinct type of surface dyslexia. They further show the possibility of good comprehension of written words when the phonological output stages are impaired.

Patterns of visual dyslexia

This study reports two Hebrew-speaking individuals with acquired visual dyslexia. They made predominantly visual errors in reading, in all positions of the target words. Although both of them produced visual errors, their reading patterns crucially differed in three respects. KD had almost exclusively letter substitutions, and SF also made letter omissions, additions, letter position errors, and between-word migrations. KD had difficulties accessing abstract letter identity in single-letter tasks, and in letter naming, unlike SF, who named letters well. KD did not show lexical effects such as frequency and orthographic neighbourhood effects and produced nonword responses, whereas SF showed lexical effects, with a strong tendency to produce word responses. We suggest that these two patterns stem from two different deficits - KD has letter identity visual dyslexia, which results from a deficit in abstract letter identification in the orthographic-visual analysis system, yielding erroneous letter identities, whereas SF has visual-output dyslexia, which results from a deficit at a later stage, a stage that combines the outputs of the various functions of the orthographic-visual analyzer.

Insights from letter position dyslexia on morphological decomposition in reading

We explored morphological decomposition in reading, the locus in the reading process in which it takes place and its nature, comparing different types of morphemes. We assessed these questions through the analysis of letter position errors in readers with letter position dyslexia (LPD). LPD is a selective impairment to letter position encoding in the early stage of word reading, which results in letter migrations (such as reading “cloud” for “could”). We used the fact that migrations in LPD occur mainly in word-interior letters, whereas exterior letters rarely migrate. The rationale was that if morphological decomposition occurs prior to letter position encoding and strips off affixes, word-interior letters adjacent to an affix (e.g., signs-signs) would become exterior following affix-stripping and hence exhibit fewer migrations. We tested 11 Hebrew readers with developmental LPD and 1 with acquired LPD in 6 experiments of reading aloud, lexical decision, and comprehension, at the single word and sentence levels (compared with 25 age-matched control participants). The LPD participants read a total of 12,496 migratable words. We examined migrations next to inflectional, derivational, or bound function morphemes compared with migrations of exterior letters. The results were that root letters adjacent to inflectional and derivational morphemes were treated like middle letters, and migrated frequently, whereas root letters adjacent to bound function morphemes patterned with exterior letters, and almost never migrated. Given that LPD is a pre-lexical deficit, these results indicate that morphological decomposition takes place in an early, pre-lexical stage. The finding that morphologically complex nonwords showed the same patterns indicates that this decomposition is structurally, rather than lexically, driven. We suggest that letter position encoding takes place before morphological analysis, but in some cases, as with bound function morphemes, the complex word is re-analyzed as two separate words. In this reanalysis, letter positions in each constituent word are encoded separately, and hence the exterior letters of the root are treated as exterior and do not migrate.

Do people with agrammatic aphasia understand verb movement

Background: Many studies report that the comprehension of sentences derived by movement of phrases is impaired in agrammatism. However, only few studies have explored the comprehension of sentences that involve a movement of the verb. In several languages, the verb can or should move to the second position of a sentence, creating VSO sentences like “Yesterday ate the girl a watermelon” from an SVO sentence. Previous studies of comprehension of verb movement either allowed the patients to use a strategy, or used grammaticality judgement tasks, which probably tap different abilities from interpretation tasks. The research was supported by a research grant from the National Institute for Psychobiology in Israel (Friedmann 2004‐5‐2b), and by the Joint German–Israeli Research Program grant (Friedmann GR‐01791). Many thanks to Ronit Szterman for her participation in the development of this experiment and to Esther Ruigendijk for her helpful comments. Aims: The present study tested the comprehension of sentences with verb movement to second position in agrammatism using a novel sentence type that prevented participants from employing strategy‐based comprehension. Comprehension was tested using sentences with verb–noun homophones and homographs. In general, the choice between the noun and the verb meaning of homophones and homographs relies on the construction of the syntactic structure of the sentence, and the syntactic role of the ambiguous word. In the current study, we used sentences in which the ambiguous word was placed at the object position, such as “Yesterday caught the bat flies in the garden” (literally transcribed into English). In order to understand whether it is a verb or a noun (whether the bat in this sentence flies, or whether it catches flies), comprehension of the relation between the moved verb and its object is required. Thus, these sentences might shed light on whether individuals with agrammatism can understand verb movement. Methods & Procedures: participants were six Hebrew‐speaking individuals with agrammatic aphasia. In Experiment 1 they paraphrased auditorily presented sentences with homophones; in Experiment 2 they read aloud and then paraphrased written sentences with heterophonic homographs. Both experiments also included, in addition to the target sentences with verb movement, matched sentences with the same homographs and homophones that did not include verb movement. Experiment 1 included 51 sentences, Experiment 2 included 48 sentences per participant. Outcomes & Results: The individuals with agrammatic aphasia failed to read and paraphrase the sentences with verb movement. They either took the object to be the verb, read the moved verb incorrectly, said they did not understand the sentence, or said that there were two parts of the sentence that did not connect. Matched sentences with the same homophones and homographs without verb movement were comprehended significantly better. Normal subjects performed correctly in all conditions. Conclusions: Not only is the comprehension of movement of phrases impaired in agrammatism, but also the comprehension of sentences derived by verb movement.