Abstract morphemes and lexical representation: the CV-Skeleton in Arabic

Overlaps in form and meaning between morphologically related words have led to ambiguities in interpreting priming effects in studies of lexical organization. In Semitic languages like Arabic, however, linguistic analysis proposes that one of the three component morphemes of a surface word is the CV-Skeleton, an abstract prosodic unit coding the phonological shape of the surface word and its primary syntactic function, which has no surface phonetic content (McCarthy, J. J. (1981). A prosodic theory of non-concatenative morphology, Linguistic Inquiry, 12 373-418). The other two morphemes are proposed to be the vocalic melody, which conveys additional syntactic information, and the root, which defines meaning. In three experiments using masked, cross-modal, and auditory-auditory priming we examined the role of the vocalic melody and the CV-Skeleton as potential morphemic units in the processing and representation of Arabic words. Prime/target pairs sharing the vocalic melody but not the CV-Skeleton consistently failed to prime. In contrast, word pairs sharing only the CV-Skeleton primed reliably throughout, with the amount of priming being as large as that observed between word pattern pairs sharing both vocalic melody and CV-Skeleton. Priming between morphologically related words can be observed when there is no overlap either in meaning or in surface phonetic form.     

Deficits in lexical and semantic processing: implications for models of normal language

The investigation of language processing following brain damage may be used to constrain models of normal language processing. We review the literature on semantic and lexical processing deficits, focusing on issues of representation of semantic knowledge and the mechanisms of lexical access. The results broadly support a componential organization of lexical knowledge—the semantic component is independent of phonological and orthographic form knowledge, and the latter are independent of each other. Furthermore, the results do not support the hypothesis that word meaning is organized into modality-specific subcomponents. We also discuss converging evidence from functional imaging studies in relation to neuropsychological results.     

Aralex: A lexical database for Modern Standard Arabic

In this article, we present a new lexical database for Modern Standard Arabic: Aralex. Based on a contemporary text corpus of 40 million words, Aralex provides information about (1) the token frequencies of roots and word patterns, (2) the type frequency, or family size, of roots and word patterns, and (3) the frequency of bigrams, trigrams in orthographic forms, roots, and word patterns. Aralex will be a useful tool for studying the cognitive processing of Arabic through the selection of stimuli on the basis of precise frequency counts. Researchers can use it as a source of information on natural language processing, and it may serve an educational purpose by providing basic vocabulary lists. Aralex is distributed under a GNU-like license, allowing people to interrogate it freely online or to download it from www.mrc-cbu.cam.ac.uk:8081/aralex .online/login.jsp.     

Extracting parity and magnitude from Arabic numerals: developmental changes in number processing and mental representation.

Children from Grades 2, 3, 4, 6, and 8 (7.8, 9.2, 9.8, 11.7, and 13. 6 years old, respectively) made speeded, bimanual parity (odd/even) judgments of the Arabic numerals 0-9. Analysis of response times indicated that from fourth grade on, parity information is retrieved directly from memory rather than being extracted by means of a mental calculation strategy. As early as Grade 3, children exhibited the SNARC (Spatial-Numerical Association of Response Codes) effect, where small numbers were responded to faster with the left hand than with the right hand, while the converse held true for large numbers. This finding, previously demonstrated only in adults, confirms that (a) children represent magnitude information in the form of a left-to-right oriented mental number line, and (b) this information is accessed obligatorily even when irrelevant. Finally, although the SNARC effect remained strong at Grade 4, it was attenuated at Grades 6 and 8 by a linguistic effect based on associations between the unmarked adjectives "even" and "right" and between the marked adjectives "odd" and "left." Copyright 1999 Academic Press.     

Context and lexical access: implications of nonword interference for lexical ambiguity resolution

To eliminate potential "backward" priming effects, Glucksberg, Kreuz, and Rho (1986) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al. to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al. were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al. is due to postlexical judgements of the congruence of the sentence context and the target, not to context constraining lexical access.     

Perceptual representation as a mechanism of lexical ambiguity resolution: An investigation of span and processing time

In 2 experiments, the authors investigated the ability of high- and low-span comprehenders to construe subtle shades of meaning through perceptual representation. High- and low-span comprehenders responded to pictures that either matched or mismatched a target object's shape as implied by the preceding sentence context. At 750 ms after hearing the sentence describing the target object, both high- and low-span comprehenders had activated a contextually appropriate perceptual representation of the target object. However, only high-span comprehenders had perceptually represented the contextually appropriate meaning immediately upon hearing the sentence, whereas low-span comprehenders required more processing time before the perceptual representation was activated. The results are interpreted in a framework of co-occurring lexical representations and perceptual-motor representations.     

Verb deficits in Alzheimer's disease and agrammatism: implications for lexical organization

This study examined the nature of verb deficits in 14 individuals with probable Alzheimer's Disease (PrAD) and nine with agrammatic aphasia. Production was tested, controlling both semantic and syntactic features of verbs, using noun and verb naming, sentence completion, and narrative tasks. Noun and verb comprehension and a grammaticality judgment task also were administered. Results showed that while both PrAD and agrammatic subjects showed impaired verb naming, the syntactic features of verbs (i.e., argument structure) influenced agrammatic, but not Alzheimer's disease patients' verb production ability. That is, agrammatic patients showed progressively greater difficulty with verbs associated with more arguments, as has been shown in previous studies (e.g., Kim & Thompson, 2000; Thompson, 2003; Thompson, Lange, Schneider, & Shapiro, 1997), and suggest a syntactic basis for verb production deficits in agrammatism. Conversely, the semantic complexity of verbs affected PrAD, but not agrammatic, patients' performance, suggesting "bottom-up" breakdown in their verb lexicon, paralleling that of nouns, resulting from the degradation or loss of semantic features of verbs.     

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.     

Phoneme monitoring and lexical processing: Evidence for associative context effects

In this paper, we propose a new version of the phoneme monitoring task that is well-suited for the study of lexical processing. The generalized phoneme monitoring (GPM) task, in which subjects detect target phonemes appearing anywhere in the test words, was shown to be sensitive to associative context effects. In Experiment 1, using the standard phoneme monitoring procedure in which subjects detect only word-initial targets, no effect of associative context was obtained. In contrast, clear context effects were observed in Experiment 2, which used the GPM task. Subjects responded faster to word-initial and word-medial targets when the target-bearing words were preceded by an associatively related word than when preceded by an unrelated one. The differential effect of context in the two versions of the phoneme monitoring task was interpreted with reference to task demands and their role in directing selective attention. Experiment 3 showed that the size of the context effect was unaffected by the proportion of related words in the experiment, suggesting that the observed effects were not due to subject strategies.     

Phonological processing and lexical access in aphasia

This study explored the relationship between on-line processing of phonological information and lexical access in aphasic patients. A lexical decision paradigm was used in which subjects were presented auditorily with pairs of words or word-like stimuli and were asked to make a lexical decision about the second stimulus in the pair. The initial phonemes of the first word primes, which were semantically related to the real word targets, were systematically changed by one or more than one phonetic feature, e.g., cat-dog, gat-dog, wat-dog. Each of these priming conditions was compared to an unrelated word baseline condition, e.g., nurse-dog. Previous work with normals showed that even a nonword stimulus receives a lexical interpretation if it shares a sufficient number of phonetic features with an actual word in the listener's lexicon. Results indicated a monotonically decreasing degree of facilitation as a function of phonological distortion. In contrast, fluent aphasics showed priming in all phonological distortion conditions relative to the unrelated word baseline. Nonfluent aphasics showed priming only in the undistorted, related word condition relative to the unrelated word baseline. Nevertheless, in a secondary task requiring patients to make a lexical decision on the nonword primes presented singly, all aphasics showed phonological feature sensitivity. These results suggest deficits for aphasic patients in the various processes contributing to lexical access, rather than impairments at the level of lexical organization or phonological organization.     

Visual word recognition and vowelization in Arabic: new evidence from lexical decision task performances

The effect of vowelization signs on the process of visual word recognition in Arabic was investigated among 41 native Arab skilled readers with age average of 30.66 ± 9.09. The participants performed a lexical decision task using three types of words and pseudowords; full, partial and non-vowelized. The results showed that for both words and pseudowords, response times were shorter and accuracy levels were higher for the non-vowelized condition compared to the other conditions of vowelization. The results reinforce the argument that automatic lexical processes during word recognition in Arabic orthography might be disturbed by supplementary information such as vowelization.     

Priming and the effects of sentence and lexical contexts on naming time: Evidence for autonomous lexical processing

Models of language processing which stress the autonomy of processing at each level predict that the semantic properties of an incomplete sentence context should have no influence on lexical processing, either facilitatory or inhibitory. An experiment similar to those reported by Fischler and Bloom (1979) and Stanovich and West (1979, 1981) was conducted using naming time as an index of lexical access time. No facilitatory effects of context were observed for either highly predictable or semantically appropriate (but unpredictable) completions, whereas strong inhibitory effects were obtained for inappropriate completions. When lexical decision time was the dependent measure, the same results were obtained, except that predictable completions now produced strong facilitation. In a further experiment the inhibitory effects of context on lexical decision times for inappropriate targets were maintained, even though unfocussed contexts were used, in which no clear expectancy for a particular completion was involved. These results were interpreted in terms of a two-factor theory which attributes the facilitation observed with the lexical decision task to postaccess decision processes which are not involved in the naming task. The inhibitory effects were attributed to interference resulting from semantic integration. In contrast to the results for sentence contexts, lexical contexts of the doctor-nurse variety produced clear facilitation effects on naming time (but no inhibitory effects). It was also shown that relatively minor variations in the type of neutral context could completely alter the relative importance of facilitation and inhibition.     

Finger-digit compatibility in Arabic numeral processing

Finger-digit response compatibility was tested by asking participants to identify Arabic digits by pressing 1 of 10 keys with all 10 fingers. The direction of the finger-digit mapping was varied by manipulating the global direction of the hand-digit mapping as well as the direction of the finger-digit mapping within each hand (in each case, from small to large digits, or the reverse). The hypothesis of a left-to-right mental number line predicted that a complete left-to-right mapping should be easier whereas the hypothesis of a representation based on finger counting predicted that a counting-congruent mapping should be easier. The results show that when all 10 fingers are used to answer, a mapping congruent with the prototypical finger-counting strategy reported by the participants leads to better performance than does a mapping congruent with a left-to-right oriented mental number line, both in palm-down and palm-up postures of the hands, and they demonstrate that finger-counting strategies influence the way that numerical information is mentally represented and processed.     

Strategies for processing unbounded dependencies: lexical information and verb-argument assignment.

This article describes 2 experiments about verb-argument relations in sentence processing in which there is no ambiguity involving the subcategorization of the verb but in which the role that the argument serves is initially unclear. Specifically, a self-paced reading experiment and an eye-tracking experiment investigated the way in which readers form unbounded dependencies when the verb is looking for both a direct object and a clause and when the filler either could be the direct object or could form part of the clause. The results suggested that readers treated the filler as the verb's direct object and probably also considered the clausal analysis at the same time. The results are interpreted with respect to current accounts of parsing.     

Spoken word recognition and lexical representation in very young children

Although children's knowledge of the sound patterns of words has been a focus of debate for many years, little is known about the lexical representations very young children use in word recognition. In particular, researchers have questioned the degree of specificity encoded in early lexical representations. The current study addressed this issue by presenting 18-23-month-olds with object labels that were either correctly pronounced, or mispronounced. Mispronunciations involved replacement of one segment with a similar segment, as in 'baby-vaby'. Children heard sentences containing these words while viewing two pictures, one of which was the referent of the sentence. Analyses of children's eye movements showed that children recognized the spoken words in both conditions, but that recognition was significantly poorer when words were mispronounced. The effects of mispronunciation on recognition were unrelated to age or to spoken vocabulary size. The results suggest that children's representations of familiar words are phonetically well-specified, and that this specification may not be a consequence of the need to differentiate similar words in production.     

Semantic processing in auditory lexical decision: Ear-of-presentation and sex differences

In this study we examined the interplay between appetitive (approach) and defensive (avoid) responses in spoken word recognition. Ninety-two right-handed participants (half women) took part in an auditory lexical decision experiment in which speech was presented to only one ear. The danger and usefulness of the word referents interacted in predicting RTs, as in previous (binaural) studies with poorer control of psycholinguistic covariates. Specifically, higher danger ratings were associated with faster RTs for words rated low on usefulness; but higher danger ratings were associated with slower RTs for words rated high on usefulness. In addition to this primary finding, men showed more lateralised performance, as indicated by significant interactions of sex and ear of presentation with word frequency, and with the animacy of the word referents. For both sexes, word frequency had a stronger effect on accuracy for speech presented to the right ear. Finally, men's but not women's RTs were related to the danger dimension. This last finding provides an intriguing avenue for future research in the area of sex differences and emotion.