Pairs Of Real Words Research Articles

Do position and lexical knowledge matter in children’s second language speech perception?

This study examines whether child second language (L2) learners’ perception of the voicing contrast in English stops depends on word position and whether lexical knowledge effects can be detected. Thirty-eight 9-year-old Korean-speaking child learners of English with beginning-level proficiency completed an AX discrimination task in English, either with real word pairs (RW; n = 20) or nonsense word pairs (NW; n = 18). Each pair comprised two words with each containing a voiceless stop or a voiced stop. The categories in comparison appeared in word-initial, word-medial, or word-final position. The analysis revealed a significant effect of position in both groups, but in different directions: Whereas the RW group performed best on the word initial contrast, the NW group performed worst on the word initial contrast. This result is in line with the possibility that L2 sounds are mapped onto L1 phonemes in beginning-level child L2 learners. Furthermore, the fact that the RW group showed lower accuracy on the AX task than the NW group provides evidence for lexical knowledge effects on beginning-level child learners’ L2 perception, indicating that immediate lexical retrieval may hinder subsequent activation of phonological representation.

Reconsolidation or interference? Aging effects and the reactivation of novel and familiar episodic memories

ABSTRACT We examined aging effects in reconsolidation and interference in episodic memory by reactivating memories for well-learned items in young and healthy older adults while controlling memory strength and the degree semantic processes contributed to memory. In Experiment 1, young and old adults learned pairs of real words and images to a strict criterion. After 24-hours, half of the images were reactivated and new words were paired with the images and learned to criterion. Following a 1-week delay, recognition and source monitoring were measured for both sets of pairings. Experiment 2 was a replication of Experiment 1, but using previously unknown novel words and unusual images. As predicted, older adults needed more trials to learn both the A-B and A-C pairings. Older adults required more trials to learn the new associations for reactivated than the not reactivated pairs, although there was no main effect of reactivation and no Age x Reactivation interaction for measures of recognition one-week later. These results are inconsistent with previous findings concerning age differences in reactivation effects in episodic memory. Instead, they suggest that once memory strength and input from semantic memory are better controlled, young and old adults perform similarly on tests of long-term recognition memory.

Phonological Working Memory for Words and Nonwords in Cerebral Cortex.

The primary purpose of this study was to identify the brain bases of phonological working memory (the short-term maintenance of speech sounds) using behavioral tasks analogous to clinically sensitive assessments of nonword repetition. The secondary purpose of the study was to identify how individual differences in brain activation were related to participants' nonword repetition abilities. We used functional magnetic resonance imaging to measure neurophysiological response during a nonword discrimination task derived from standard clinical assessments of phonological working memory. Healthy adult control participants (N = 16) discriminated pairs of real words or nonwords under varying phonological working memory load, which we manipulated by parametrically varying the number of syllables in target (non)words. Participants' cognitive and phonological abilities were also measured using standardized assessments. Neurophysiological responses in bilateral superior temporal gyrus, inferior frontal gyrus, and supplementary motor area increased with greater phonological working memory load. Activation in left superior temporal gyrus during nonword discrimination correlated with participants' performance on standard clinical nonword repetition tests. These results suggest that phonological working memory is related to the function of cortical structures that canonically underlie speech perception and production.

The influence of lexical status in the perception of English allophones by Korean learners

This study investigated whether the allophonic contrast in the second language (L2) may require contact with the lexicon to influence the perception. Given that English medial voiceless stops occur with aspiration in stressed, but without aspiration in unstressed syllables, Korean learners of English were tested for aspirated and unaspirated allophones of /p/ for perceptual preference in appropriate and inappropriate stress contexts in the second syllable of disyllabic words. The stimuli included four types of non-words and eight pairs of real words (four pairs each for high-frequency and low-frequency words), and participants were asked to judge the perceptual preference of each token on a 7-scale (1 = a bad example, 7 = a good example). The results demonstrated that in tests with non-words, there was no significant difference in the ratings as a function of context appropriateness (e.g., [ípɚ] vs. [íphɚ]), with higher rankings for initially-stressed words. By contrast, in real words, participants preferred the correct allophones (e.g., [képɚ] vs. [képhɚ] “caper”). The frequency of real words further showed a significant effect. This finding suggests that allophony in L2 is driven by lexicality (Whalen et al., 1997). Exemplar theory (Pierrehumbert 2001, 2002) provides a more effective means of modeling this finding than do traditional approaches.

There is no clam with coats in the calm coast: Delimiting the transposed-letter priming effect

In this article, we explore the transposed-letter priming effect (e.g., jugde-JUDGE vs. jupte-JUDGE), a phenomenon that taps into some key issues on how the brain encodes letter positions and has favoured the creation of new input coding schemes. However, almost all the empirical evidence from transposed-letter priming experiments comes from nonword primes (e.g., jugde-JUDGE). Indeed, previous evidence when using word-word pairs (e.g., causal-CASUAL) is not conclusive. Here, we conducted five masked priming lexical decision experiments that examined the relationship between pairs of real words that differed only in the transposition of two of their letters (e.g., CASUAL vs. CAUSAL). Results showed that, unlike transposed-letter nonwords, transposed-letter words do not seem to affect the identification time of their transposed-letter mates. Thus, prime lexicality is a key factor that modulates the magnitude of transposed-letter priming effects. These results are interpreted under the assumption of the existence of lateral inhibition processes occurring within the lexical level-which cancels out any orthographic facilitation due to the overlapping letters. We examine the implications of these findings for models of visual-word recognition.

Phonological therapy within a psycholinguistic framework: Promoting change in a child with persisting speech difficulties

Single case studies are a valuable means of providing information about the outcomes of speech and language intervention. Many previous studies have used phonological analysis as a theoretical basis, while others have used psycholinguistic models. The present study combines these approaches to assessment, intervention and evaluation of outcomes. The aim of the research was to determine if intensive psycholinguistically based intervention could result in (a) specific and (b) generalized improvements in the speech production of a child with severe and persisting phonological difficulties. A single subject research design was used with pre- and post-intervention assessment carried out. Assessment took place at two levels: the macro level focused on global change in the child's speech processing system using psycholinguistic speech profiling and phonological analyses; the micro assessment focused on specific, treated (and matched control) stimuli. There were three phases of intervention with a total of 30 hours of therapy. Micro evaluation showed significant changes in Katy's single word and connected speech production--as well as in other areas such as spelling and auditory discrimination of closely related real word pairs. Macro evaluation revealed significant improvement in speech severity indices (PCC, PPC), and gains in her ability to discriminate between closely related real word pairs. These changes were maintained at follow-up seven months after intervention had ceased. Specific and intensive intervention brought about significant improvements in this child's speech, spelling and auditory discrimination at the micro level, and in speech and auditory discrimination at a macro level. The macro level assessments reveal persisting core deficits requiring further focused intervention before changes can be observed more widely. When carefully defined and evaluated, speech and language intervention can have positive outcomes for children with severe and persisting speech difficulties.

Phonology and neuropsychology of the English past tense

The double dissociation between the regular and irregular past tense in English has been explained in terms of dual and single mechanism accounts. In previous research we have argued that problems with the regular past tense in patients with left inferior frontal damage arise from morpho-phonological parsing difficulties [Trends in Cognitive Science 2 (1998) 428]. This claim has recently been challenged by a single mechanism connectionist account which argues that a general phonological processing deficit causes the poor performance on the regular past tense, with morphological factors playing no explicit role [Proceedings of the National Academy of Sciences 96 (1999) 7592]. We used a speeded judgement task with four patients who have documented difficulties with the regular past tense to contrast the claims made by these different approaches. We compared patients’ ability to detect the difference between the past tense and stem of regular ( hugged/ hug) and irregular ( taught/ teach) past tense verbs, as well as matched “pseudo” pairs ( trade/ tray and port/ peach). These real word conditions were accompanied by matched sets of non-words (e.g. nugged/ nug). Patients’ latencies to the regular past tense real word-pairs were consistently slower than in any other condition. To test for a general phonological processing deficit, we conducted several tests of phonological processing ability. The results show that the patients had a range of difficulties in phonological processing, from very mild to severe. This did not correlate with their performance on the speeded judgement task. We interpret this pattern of results as support for a specialised morpho-phonological processing mechanism which can be dissociated from other phonological processes and which is used directly in the processing of the regular past tense in a dual-mechanism system.

‘‘SLIP-ing’’ in phonologically similar neighborhoods

Phonological speech errors are the class of speech errors in which one or more phonemes are added, deleted, substituted, or reversed. Previous work [Dell (1990); Stemberger and MacWhinney (1986)] has found that low-frequency words are more likely to be involved in phonological speech errors than high-frequency ones. If word frequency, influences performance in speech production, do other characteristics of words, such as neighborhood density or neighborhood frequency, influence speech production? The influence of phonologically similar neighborhoods on a type of whole word speech error (malapropisms) has previously been demonstrated [Vitevitch (1996)]. The present research examined the influence of phonologically similar neighborhoods on phonological speech errors. Using the SLIPS technique [Motley and Baars (1976)], phonological speech errors were elicited from participants with real word pairs that varied in their neighborhood characteristics. The results show that low-frequency words ‘‘slipped’’ more often than high-frequency ones, replicating past results from error corpora and from other studies using this methodology. Moreover, words with sparse phonologically similar neighborhoods tended to ‘‘slip’’ more than words with dense phonologically similar neighborhoods. The implications for these findings on models of speech production, speech perception, and lexical representation are discussed.

The phonological representation of [voice] in speech perception.

This paper examines to what extent phonological representations affect word identification. The contrast under investigation involves the interaction between voicing and vowel length in Dutch. Dutch has underlying contrasts both in obstruent voicing and in vowel length. The voicing contrast is neutralized on the surface in syllable-final position. Also, both long and short vowels are lengthened by some 25 msec when followed by medial voiced obstruents. The present study investigated whether this vowel length cue influenced listeners when hearing stimuli with ambiguous vowel duration in an identical, neutralized consonantal context in which the underlying representation of the obstruent following the vowel differed in voicing. A vowel length continuum ([at] to [a:t]) was created and appended to initial consonants to make two pairs of real words. Each pair differed in vowel length with opposite underlying final consonant representations: /zat/-/za:d/, and /stad/-/sta:t/. Our question was whether the vowel category boundaries would be different in pairs like /zat/-/za:d/ as compared to /stad/-/sta:t/. Although the underlying consonant is either voiced or voiceless, the surface word-final consonant for both pairs of stimuli is always voiceless ([t]). If the listener uses a surface representation with a voiceless consonant to recognize the words, there should be no difference in categorization of the vowel-length continua. The results of a vowel categorization task, however, showed a significant difference in the location of the phoneme boundaries between the two continua, suggesting that listeners' perception seems to be guided by the underlying phonological representation of words.

Syntactic priming effects in aphasia: An investigation of local syntactic dependencies

This study explored on-line processing of local syntactic dependencies in normal subjects and in Broca's and Wernicke's aphasics using a lexical decision paradigm. In addition, subjects performed a grammaticality judgement task on the real word pairs used in the lexical decision tasks. Results of two experiments for normal subjects indicated different syntactic priming effects as a function of the type of local syntactic dependency. Word pairs that formed a single constituent phrase, i.e., a verb phrase, showed both facilitory and inhibitory effects, whereas word pairs that reflected local syntactic dependencies across a phrase boundary, i.e., pronoun verb, showed only inhibitory effects. Broca's aphasics failed to show facilitory effects when presented with word pairs forming a single constituent phrase but, similar to normals, did show inhibition when presented with word pairs that reflected local syntactic dependencies across a phrase boundary. In contrast, Wernicke's aphasics failed to show inhibitory effects in both experiments. The implications of these results for theories of language processing deficits in aphasia are considered.

DISTRIBUTION OF CORTICAL NEURAL NETWORKS INVOLVED IN WORD COMPREHENSION AND WORD RETRIEVAL

Six normal volunteers were studied with positron emission tomography to identify the cortical neural networks that participate in the processing of single words. Activity-related changes in regional cerebral blood flow were measured consecutively on 6 occasions in each subject, 2 while the subject was at rest and 4 while single word language tasks were being performed. The data from each subject were standardized for brain shape and size, reconstructed parallel to the intercommissural line, normalized for global flow differences, and then averaged for each activation condition across the 6 subjects. Significant areas of change in rCBF (P less than 0.05, with appropriate Bonferroni corrections) between task and rest conditions were displayed with reference to the coordinates of a standard neuroanatomical atlas. We have demonstrated that categorical judgements on heard pairs of real words activate neural networks along both superior temporal gyri, but with an anatomical distribution no different from that seen when the subjects listened to nonwords: the tasks would appear to be very different in cognitive demands but not in terms of the distribution of activation. However, during a verb generation task that involved thinking of verbs appropriate to heard nouns presented at a slow rate, the only temporal region activated was the left posterior superior temporal association cortex (Wernicke's area). Further analysis showed that whereas activation in other superior temporal regions, both left and right, correlated with rates of word presentation during the 4 tasks, there was no such correlation in Wernicke's area; evidence that this site is responsible for more than early acoustic processing. During verb generation there was also activation of left premotor and prefrontal cortex (including Broca's area and the supplementary motor area). The supplementary motor area is thought to be involved in the motor planning of speech. The subjects did not vocalize during the task, and therefore it would appear that the act of retrieving words from semantic memory activates networks concerned with the production of speech sounds. We conclude that single word comprehension and retrieval activate very different distributed regions of cerebral cortex, with Wernicke's area the only region engaged by both processes and with participation during silent word generation of networks involved in vocalization.