Neural responses to morphological, syntactic, and semantic properties of single words: an fMRI study

Dissociations in the recognition of specific classes of words have been documented in brain-injured populations. These include deficits in the recognition and production of morphologically complex words as well as impairments specific to particular syntactic classes such as verbs. However, functional imaging evidence for distinctions among the neural systems underlying these dissociations has been inconclusive. We explored the neural systems involved in processing different word classes in a functional Magnetic Resonance Imaging study, contrasting four groups of words co-varying morphological complexity (simple, monomorphemic words vs complex derived or inflected words) and syntactic class (verbs vs nouns/adjectives). Subtraction of word from letter string processing showed activation in left frontal and temporal lobe regions consistent with prior studies of visual word processing. No differences were observed for morphologically complex and simple words, despite adequate power to detect stimulus specific effects. A region of posterior left middle temporal gyrus showed significantly increased activation for verbs. Post hoc analyses showed that this elevated activation could also be related to semantic properties of the stimulus items (verbs have stronger action associations than nouns, and action association is correlated with activation). Results suggest that semantic as well as syntactic factors should be considered when assessing the neural systems involved in single word comprehension.     

Affixal homonymy triggers full-form storage, even with inflected words, even in a morphologically rich language

This paper investigates whether affixal homonymy, the phenomenon that one affix form serves two or more semantic/syntactic functions, affects lexical processing of inflected words in a similar way for a morphologically rich language such as Finnish as for morphologically restricted languages such as Dutch and English. For the latter two languages, there is evidence that affixal homonymy triggers full-form storage for inflected words (Bertram, R., Schreuder, R., and Baayen, R. H. (in press). The balance of storage and computation in morphological processing: the role of word formation type, affixal homonymy, and productivity. Journal of Experimental Psychology: Learning, Memory, and Cognition; Sereno and Jongman (1997). Processing of English inflectional morphology. Memory and Cognition, 25, 425-437). Two visual lexical decision experiments show the same pattern for Finnish. Apparently, the substantially richer morphology in Finnish does not prevent full-form storage for inflected words when the affix is homonymic.     

Recall of morphologically complex forms is affected by memory task but not dyslexia

The authors studied the effect of morphological complexity on working memory in list recall tasks with base words (boy), inflected words (boy + 's) and derived words (boy + hood) in a morphologically rich language: Finnish. Simple serial recall was compared to complex working memory tasks, combining word recall with sentence verification in 8-year-old normally reading participants, dyslexic children, and adults. The normally reading children performed better than dyslexic children on both memory tasks and a test of morphology. Base words were better recalled than morphologically complex words. Memory was better for derived than inflected words in simple but not complex span tasks. There was no interaction between word type and reading group and thus no suggestion of dyslexia being associated with specific problems to represent complex morphology in working memory. Morphological processing in working memory appeared to depend on the task.     

A morphological effect obtains for isolated words but not for words in sentence context

The effect of morphological complexity on word identification was studied in three experiments conducted in Finnish, employing the same set of target nouns. In Experiment 1, the target nouns were presented in isolation, and lexical decision times were employed as lexical access measures. In Experiments 2 and 3, the same words were embedded in sentence contexts, where both the inflected and non-inflected forms were equally plausible, and eye fixation patterns (Exp. 2) and lexical decision latencies (Exp. 3) were recorded. The experiment with isolated words replicated previous lexical decision studies by showing more effortful processing for inflected than monomorphemic nouns. However, this morphological complexity effect did not generalise to the context experiments; fixation durations and response latencies were highly similar for inflected and monomorphemic words. It is suggested that, at least for the type of inflected nouns studied, the morphological effect observed for isolated words may derive from the syntactic and/or semantic level and not necessarily from the lexical level, as previously assumed.     

The contribution of frequency and semantic similarity to morphological processing

This research investigated the role of frequency and semantic factors in the processing of morphologically complex words. Unaffixed targets were immediately preceded by either inflected or derived primes that were either high or low in frequency. In Experiment 1, low-frequency inflections and derivations produced equivalent priming effects, whereas high-frequency inflections produced more priming than derivations. In Experiment 2, both semantic and morphological priming varied as a function of SOA (50, 150, and 250 ms). The difference in priming of inflections and derivations increased as SOA increased. Results suggest that frequency and semantic similarity interactively modulate the magnitude of morphological priming and, by inference, affect the processing of morphologically complex words. Dual-route and connectionist accounts are discussed.     

Cross-modal morphological priming in French

We investigated the lexical representation of morphologically complex words in French using a cross-modal priming experiment. We asked if the lexical representation for derivationally suffixed and prefixed words is morphologically structured and how this relates to the phonological transparency of the surface relationship between stem and affix. Overall we observed a clear effect of the morphological structure for derived words, an effect that is not explicable by a formal effect. Prefixed words prime their stems, even when they have a phonologically opaque relationship, and a prefixed word primes another prefixed word derived from the same stem. However, suffixed words prime their stems only if their relationship is phonologically transparent. Two suffixed words derived from the same stem prime each other. These two latter results differ from those observed in English by Marslen-Wilson, Tyler, Waksler, and Older (1994). We argue that it is the specific properties of the language, such as rhythm, that could explain the differences between the results observed for the two languages and we propose a model where prefixed and suffixed words are decomposed at different stages during their identification process.     

Morphological priming in the German mental lexicon.

We present results from cross-modal priming experiments on German participles and noun plurals. The experiments produced parallel results for both inflectional systems. Regular inflection exhibits full priming whereas irregularly inflected word forms show only partial priming: after hearing regularly inflected words (-t participles and -s plurals), lexical decision times on morphologically related word forms (presented visually) were similar to reaction times for a base-line condition in which prime and target were identical, but significantly shorter than in a control condition where prime and target were unrelated. In contrast, prior presentation of irregular words (-n participles and -er plurals) led to significantly longer response times on morphologically related word forms than the prior presentation of the target itself. Hence, there are clear priming differences between regularly and irregularly inflected German words. We compare the findings on German with experimental results on regular and irregular inflection in English and Italian, and discuss theoretical implications for single versus dual-mechanism models of inflection.     

Relations among regular and irregular morphologically related words in the lexicon as revealed by repetition priming

Several experiments examined repetition priming among morphologically related words as a tool to study lexical organization. The first experiment replicated a finding by Stanners, Neiser, Hernon, and Hall (Journal of Verbal Learning and Verbal Behavior, 1979,18, 399-412), that whereas inflected words prime their unaffixed morphological relatives as effectively as do the unaffixed forms themselves, derived words are effective, but weaker, primes. The experiment also suggested, however, that this difference in priming may have an episodic origin relating to the less formal similarity of derived than of inflected words to unaffixed morphological relatives. A second experiment reduced episodic contributions to priming and found equally effective priming of unaffixed words by themselves, by inflected relatives, and by derived relatives. Two additional experiments found strong priming among relatives sharing the spelling and pronunciation of the unaffixed stem morpheme, sharing spelling alone, or sharing neither formal property exactly. Overall, results with auditory and visual presentations were similar. Interpretations that repetition priming reflects either repeated access to a common lexical entry or associative semantic priming are both rejected in favor of a lexical organization in which components of a word (e.g., a stem morpheme) may be shared among distinct words without the words themselves, in any sense, sharing a “lexical entry.”     

第二语言学习者形态复杂词的加工机制

大多数语言中, 形态复杂词所占的比例很高。形态复杂词形-义映射的规律性使得读者不仅能直接从心理词典中提取整词语义, 还可以利用形态规则来建构词语的语义。研究发现, 母语者可以利用形态规则来加工复杂词, 但第二语言(二语)学习者的研究结果存在较大的分歧, 且表现出和母语者不一样的结果模式。基于补充学习系统理论和情景性二语者假设, 我们尝试提出了二语形态复杂词加工机制的观点, 并据此解释研究分歧出现的原因。未来的研究需要探究词汇形态家族大小等因素对二语形态复杂词加工的影响, 以及揭示二语形态复杂词加工的神经机制。     

母语者与二语者屈折词和派生词语素加工的差异

语素是构成词汇的最小功能单位,是能够表达独立语义的最小成分。语素加工是指基于一定的构词规则,将语素复杂词汇进一步分解为多个语素,通过加工和重组语素,建构起对整词意义的理解。有关英语语素加工的研究发现,不仅母语者和二双语者的加工模式存在很大差异,对于屈折和派生这两种英语中重要的语素复杂词汇,其加工模式也存在较大差异,本文重点讨论了英语母语者与英语二语者对屈折和派生词加工模式的差异、成因以及影响因素。最后提出了今后需要进一步研究的问题。     

句子语境中语义联系效应和句法效应的研究

通过对比研究句子语境中句法成分和语义联系对目标词加工的不同影响,来探讨句子语境的作用机制和作用点问题。实验一采用词汇命名任务研究发现,句法违反对词汇命名会产生抑制作用,而语义违反对词汇命名却没有发现抑制作用。实验二利用词汇决定任务发现,句法和语义成分影响词汇决定任务,句法违反和语义违反对词汇决定任务均会产生抑制作用。结果表明,句子语境加工中,对内容词语义整合过程中存在一个句法成分的独立加工水平。     

Examining lateralized semantic access using pictures

A divided visual field (DVF) experiment examined the semantic processing strategies employed by the cerebral hemispheres to determine if strategies observed with written word stimuli generalize to other media for communicating semantic information. We employed picture stimuli and vary the degree of semantic relatedness between the picture pairs. Participants made an on-line semantic relatedness judgment in response to sequentially presented pictures. We found that when pictures are presented to the right hemisphere responses are generally more accurate than the left hemisphere for semantic relatedness judgments for picture pairs. Furthermore, consistent with earlier DVF studies employing words, we conclude that the RH is better at accessing or maintaining access to information that has a weak or more remote semantic relationship. We also found evidence of faster access for pictures presented to the LH in the strongly-related condition. Overall, these results are consistent with earlier DVF word studies that argue that the cerebral hemispheres each play an important and separable role during semantic retrieval.     

The relationship between morphological awareness and reading comprehension in Spanish‐speaking children

In the last decades, a series of studies has explored the role of morphological awareness on reading comprehension. Path analysis studies performed in English have shown that morphological awareness benefits reading comprehension both directly and indirectly, through word decoding. This issue has seldom been explored in Spanish. The aim of this study was to replicate in Spanish the results previously found in English. We used path analysis to assess three alternative models of the relationship between morphological awareness, word decoding and reading comprehension in 4th grade Spanish‐speaking children. Contrary to English, we found that morphological awareness benefits reading comprehension only directly. We conclude that in Spanish, in which accurate and fluent pronunciation of written words can be achieved through grapheme‐to‐phoneme conversion rules, morphological awareness does not help the correct pronunciation of words. Thus, morphological awareness is not relevant for word decoding in Spanish but is related to reading comprehension since this type of morphological knowledge provides access to the semantic and syntactic information of new words.     

Effects of morphological complexity on phonological output deficits in fluent and nonfluent aphasia

This study examined the effects of morphological complexity on aphasic speakers with lexical-phonological output deficits. Subjects were two fluent and two nonfluent aphasic speakers who repeated morphologically simple words at the same level of accuracy and whose errors were virtually all phonological in nature. They were asked to repeat a variety of morphologically complex (i.e., affixed) words. Results were interpreted within our two-stage model of lexical-phonological production (Kohn & Smith, 1994, 1995), which we expand to include a distinction between derivational and inflectional morphology. When comparing overall performance levels between morphologically simple and complex words, only three subjects exhibited more difficulty repeating the morphologically complex targets. Nevertheless, when comparing repetition accuracy between different types of morphologically complex words (e.g., derived vs. inflected), all four subjects displayed similar patterns. These findings suggested that while morphological complexity has different effects on the two stages within the lexical-phonological output system, the relative effects of different morphological structures are constant. At the level of error analysis, patterns of affix errors distinguished the nonfluent from the fluent subjects in ways that are reminiscent of the affix errors associated with agrammatic and paragrammatic speech. This finding raised questions concerning the relationship between morphosyntactic and morphophonological deficits.     

Deep dysphasia: analysis of a rare form of repetition disorder

"Deep dysphasia" is the parallel in repetition to the reading impairment deep dyslexia. Our patient, S.M., showed part of speech, word/nonword, and concreteness effects in repetition, and he made semantic errors, but his oral reading was relatively spared. Further testing indicated that S.M. did not have difficulty perceiving spoken stimuli or deciding their lexical status, but he was deficient at semantically processing spoken words. Moreover, his phonemic memory was severely impaired. We argue that the routes for repetition (lexical and nonlexical) that function without semantic mediation were defective and that deficits in phonemic memory further diminished their effectiveness, since initial phonological encoding of spoken words was not available to guide the output stages of phonological processing. In addition, the semantically mediated route for repetition was unreliable because semantic processing was faulty and S.M. could not accurately label concepts.     

Recognition of Inflected Words in a Morphologically Limited Language: Frequency Effects in Monolinguals and Bilinguals

The effect of word frequency on the processing of monomorphemic vs. inflected words was investigated in a morphologically relatively limited language, Swedish, with two participant groups: early Finnish–Swedish bilinguals and Swedish monolinguals. The visual lexical decision results of the monolinguals suggest morphological decomposition with low-frequency inflected nouns, while with medium- and high-frequency inflections, full-form processing was apparently employed. The bilinguals demonstrated a similar pattern. The results suggest that morpheme-based recognition is employed even in a morphologically limited language when the inflectional forms occur rarely. With more frequent inflectional forms, full-form representations have developed for both mono- and bilingual speakers. In a comparable study employing a morphologically rich language, Finnish, Lehtonen and Laine (2003, Bilingualism: Language and Cognition, 6, 213–225) observed full-form access only at the high-frequency range and only for monolinguals. These differences suggest that besides word frequency and language background, the morphological richness of a language affects the processing mode employed with polymorphemic wordsThis study was financially supported by a grant (#20010) from the Joint Committee of the Nordic Social Science Research Councils (NOS-S). We are grateful for Jonna Kortelahti- Brunnsteiner for recruitment and testing of part of the bilingual participants     

Evidence for an abstract lexical representation of word structure

Subjects were required to judge whether a particular visually presented word was a homophone or not. When instructed not to read the word aloud, subjects had difficulty with words whose orthography suggested a morphological structure different from that suggested by their homophones, for example, FINED (homophonic with FIND). There were no major problems encountered when the two members of the homophonic pair had the same morphological structure, for example, KNEAD. When subjects were instructed to read the word aloud before making a decision, however, their performance on the morphologically different items improved markedly. This result suggests, first, that inflected words are represented in the lexicon as stem plus affix and, second, that silent reading involves a more abstract phonological representation than the actual phonetic representation produced by reading aloud.     

Working memory and error detection in texts: what are the roles of the central executive and the phonological loop?

Subjects performed a text error detection task, either alone or in conjunction with a secondary task aimed at specifically hindering the functioning of either the central executive in working memory or of the phonological loop. We focused on the decline in detection performance as a function of the type of error to be detected (typographical, orthographic, or semantic/syntactic) and the processing span required for detection (one word, several words within the same clause, or several clauses). The results showed that the central executive in working memory is involved in detecting semantic/syntactic errors and in detecting orthographic ones, but not in detecting typographical errors. Moreover, the degree of involvement increases with the processing span. The phonological loop is involved in detection whenever processing above the word level is required. As observed in many studies, these results suggest that the difficulty subjects have detecting semantic errors as compared to other types of errors is due to the heavier working memory load: maintenance of the phonological representation and greater involvement of the central executive. © 1998 John Wiley & Sons, Ltd.     

The role of syntactic context in word recognition

This study examines the role of syntactic information in word recognition. Subjects made a word-nonword decision regarding a target string that was preceded by a syntactically appropriate word, a semantically related word, or an unrelated word. In Experiment 1, with syntactic and semantic trials assigned to separate blocks, syntactically and semantically appropriate context significantly reduced lexical decision for subsequent target words, compared with unrelated contexts. In Experiment 2, the syntactically and semantically primed trials were either blocked separately or mixed within the same block. Significant syntactic and semantic effects were both observed in the blocked condition, but only the semantic effect was obtained in the mixed condition     

Rapid extraction of gist from visual text and its influence on word recognition

Two experiments explored rapid extraction of gist from a visual text and its influence on word recognition. In both, a short text (sentence) containing a target word was presented for 200 ms and was followed by a target recognition task. Results showed that participants recognized contextually anomalous word targets less frequently than contextually consistent counterparts (Experiment 1). This context effect was obtained when sentences contained the same semantic content but with disrupted syntactic structure (Experiment 2). Results demonstrate that words in a briefly presented visual sentence are processed in parallel and that rapid extraction of sentence gist relies on a primitive representation of sentence context (termed protocontext) that is semantically activated by the simultaneous presentation of multiple words (i.e., a sentence) before syntactic processing.