Biomedical subjects

N Sebastián-Gallés

Publications and source records attributed to N Sebastián-Gallés.

12 recordsLinked to original sources

PubMed2006

Myelination of language-related areas in the developing brain.

BACKGROUND: The rapid development of language abilities in early childhood coincides with a similarly accelerated progression in brain maturation. OBJECTIVE: To quantitate myelination in the lateral part of the verbal left hemisphere from birth to 3 years in the living human brain. METHODS: One hundred children (mean age 16.6 months) were examined using three-dimensional MRI, and a subgroup of 40 children were also evaluated behaviorally. The volume of myelinated white matter was measured in language-related temporal and frontal regions and in the central sensorimotor region. A method was developed to compose a movie sequence for all the myelination process using volumetric data. RESULTS: A plot of age against relative volume of myelinated white matter graphically detailed the myelination progress in the lateral brain. The changes started in sensorimotor white matter and the Heschl gyrus and ultimately extended to the language-related areas. Both comprehension and production regions showed a very similar myelination course, suggesting simultaneous maturation of the temporofrontal language network. The movie sequence of white matter images dynamically displayed the anatomic details of myelin deposition in this part of the brain. The analysis of language performance showed acceleration in children's vocabulary after 18 months, once a rapid myelination phase was attained in the language brain. CONCLUSIONS: This volumetric study may contribute to further characterize the early stages of brain maturation by showing the fine progression of myelin deposition in the language domains and illustrating its relationship to children's vocabulary acquisition.

Brain↗

PubMed2005

Morphological processing in early bilinguals: an ERP study of regular and irregular verb processing.

Although the age of acquisition of a language has an effect when learning a second language, the similarity between languages may also have a crucial role. The aim of the present study is to understand the influence of this latter factor in the acquisition of morphosyntactic information. With this purpose, two groups of highly proficient early Catalan-Spanish bilinguals were presented with a repetition-priming paradigm with regular and irregular verbs of Spanish. Catalan and Spanish have a similar suffix (-o) for regular verbs and completely different alternations for irregular verbs. Two types of irregular verbs were studied (semi-regular verbs with a systematic diphthong alternation, sentir-siento, and verbs with idiosyncratic changes, venir-vengo). Regular verbs showed the same centro-parietal N400 priming effect in the second-language speakers (L2) as in primary-language (L1) speakers. However, differences between groups, in the ERP pattern and the topography of the N400 effect, were observed for irregular morphology. In L1 speakers, the N400 effect was attenuated only for semi-regular verbs. In contrast, L2 speakers showed a reduced N400 priming effect in both irregular contrasts. This pattern of results suggests that the similarity between languages may help for similar structures but may interfere for dissimilar structures, at least when the two languages have very similar morphological systems.

Adolescent↗

PubMed2001

The effects of acoustic mismatch and selective listening on repetition deafness.

Previous research (i.e., M. Miller & D. O. MacKay, 1994, 1996) has suggested that repetition deafness (RD), like repetition blindness, is robust to physical identity and that it consists in a failure to recall specifically the 2nd of the 2 critical targets (C1 and C2). However, some confounds due to memory load and response biases make available evidence inconclusive. Experiment 1 provided a strong test of RD between physically mismatching stimuli using a low memory load methodology. In Experiment 2, the same presentation method was combined with a selective recall task to find that RD is specific of C2. Experiments 3A and 3B showed, through an attentional manipulation, that RD is eliminated when people can successfully ignore C1 but not otherwise. It is argued that present data favor a perceptual interpretation of the RD. Furthermore, the present results support the hypothesis of recognition failure as opposed to the alternative token individuation failure hypothesis.

Analysis of Variance↗

PubMed2001

The influence of native-language phonology on lexical access: exemplar-Based versus abstract lexical entries.

This study used medium-term auditory repetition priming to investigate word-recognition processes. Highly fluent Catalan-Spanish bilinguals whose first language was either Catalan or Spanish were tested in a lexical decision task involving Catalan words and nonwords. Spanish-dominant individuals, but not Catalan-dominant individuals, exhibited repetition priming for minimal pairs differing in only one feature that is nondistinctive in Spanish (e.g.,[see text]), thereby indicating that they processed these words as homophones. This finding provides direct evidence both that word recognition uses a language-specific phonological representation and that lexical entries are stored in the mental lexicon as abstract forms.

Adult↗

PubMed2001

A robust method to study stress "deafness".

Previous research by Dupoux et al. [J. Memory Lang. 36, 406-421 (1997)] has shown that French participants, as opposed to Spanish participants, have difficulties in distinguishing nonwords that differ only in the location of stress. Contrary to Spanish, French does not have contrastive stress, and French participants are "deaf" to stress contrasts. The experimental paradigm used by Dupoux et al. (speeded ABX) yielded significant group differences, but did not allow for a sorting of individuals according to their stress "deafness." Individual assessment is crucial to study special populations, such as bilinguals or trained monolinguals. In this paper, a more robust paradigm based on a short-term memory sequence repetition task is proposed. In five French-Spanish cross-linguistic experiments, stress "deafness" is shown to crucially depend upon a combination of memory load and phonetic variability in F0. In experiments 3 and 4, nonoverlapping distribution of individual results for French and Spanish participants is observed. The paradigm is thus appropriate for assessing stress deafness in individual participants.

Adult↗

PubMed2000

Constraints of vowels and consonants on lexical selection: cross-linguistic comparisons.

Languages differ in the constitution of their phonemic repertoire and in the relative distinctiveness of phonemes within the repertoire. In the present study, we asked whether such differences constrain spoken-word recognition, via two word reconstruction experiments, in which listeners turned non-words into real words by changing single sounds. The experiments were carried out in Dutch (which has a relatively balanced vowel-consonant ratio and many similar vowels) and in Spanish (which has many more consonants than vowels and high distinctiveness among the vowels). Both Dutch and Spanish listeners responded significantly faster and more accurately when required to change vowels as opposed to consonants; when allowed to change any phoneme, they more often altered vowels than consonants. Vowel information thus appears to constrain lexical selection less tightly (allow more potential candidates) than does consonant information, independent of language-specific phoneme repertoire and of relative distinctiveness of vowels.

Choice Behavior↗

PubMed2000

Adaptation to time-compressed speech: phonological determinants.

Perceptual adaptation to time-compressed speech was analyzed in two experiments. Previous research has suggested that this adaptation phenomenon is language specific and takes place at the phonological level. Moreover, it has been proposed that adaptation should only be observed for languages that are rhythmically similar. This assumption was explored by studying adaptation to different time-compressed languages in Spanish speakers. In Experiment 1, the performances of Spanish-speaking subjects who adapted to Spanish, Italian, French, English, and Japanese were compared. In Experiment 2, subjects from the same population were tested with Greek sentences compressed to two different rates. The results showed adaptation for Spanish, Italian, and Greek and no adaptation for English and Japanese, with French being an intermediate case. To account for the data, we propose that variables other than just the rhythmic properties of the languages, such as the vowel system and/or the lexical stress pattern, must be considered. The Greek data also support the view that phonological, rather than lexical, information is a determining factor in adaptation to compressed speech.

Adaptation, Psychological↗

PubMed1999

Online processing of native and non-native phonemic contrasts in early bilinguals.

There is considerable debate about whether bilinguals can distinguish L2 phonemic contrasts as efficiently as first language speakers can. To test this issue, a group of highly proficient Spanish-dominant Catalan-Spanish bilinguals (who had been exposed to Catalan between the ages of 3 and 4, but who, previous to this age, had been exposed only to Spanish) and another group of Catalan-dominant bilinguals (who had been exposed to Catalan from birth) were compared in a gating task. We developed a variation of the gating procedure that included a two-alternative forced choice test after each fragment was played. The differences between the two alternatives consisted of phonemic contrasts existing in Catalan but not in Spanish. Four contrasts were tested: two vocalic contrasts [symbols: see text] and two consonantal contrasts [symbols: see text]. The results showed that Spanish-dominant bilinguals, even the subset who were able to make correct identifications at the last gate, systematically performed worse than the group of Catalan-dominant bilinguals, needing longer portions of the signal to be able to correctly identify the stimuli. We argue that these results support the hypothesis that L1 shapes the perceptual system at early stages of development in such a way that it will determine the perception of non-native phonemic contrasts, even if there is extensive and early exposure to L2.

Adult↗

PubMed1998

Effects of phoneme repertoire on phoneme decision.

In three experiments, listeners detected vowel or consonant targets in lists of CV syllables constructed from five vowels and five consonants. Responses were faster in a predictable context (e.g., listening for a vowel target in a list of syllables all beginning with the same consonant) than in an unpredictable context (e.g., listening for a vowel target in a list of syllables beginning with different consonants). In Experiment 1, the listeners' native language was Dutch, in which vowel and consonant repertoires are similar in size. The difference between predictable and unpredictable contexts was comparable for vowel and consonant targets. In Experiments 2 and 3, the listeners' native language was Spanish, which has four times as many consonants as vowels; here effects of an unpredictable consonant context on vowel detection were significantly greater than effects of an unpredictable vowel context on consonant detection. This finding suggests that listeners' processing of phonemes takes into account the constitution of their language's phonemic repertoire and the implications that this has for contextual variability.

Humans↗

PubMed1997

A limit on behavioral plasticity in speech perception.

It is well attested that we perceive speech through the filter of our native language: a classic example is that of Japanese listeners who cannot discriminate between the American /l/ and /r/ and identify both as their own /r/ phoneme (Goto. H., 1971. Neuropsychologia 9, 317-323.). Studies in the laboratory have shown, however, that perception of non-native speech sounds can be learned through training (Lively, S.E., Pisoni, D.B., Yamada, R.A., Tohkura, Y.I., Yamada, T., 1994. Journal of the Acoustical Society of America 96 (4), 2076-2087). This is consistent with neurophysiological evidence showing considerable experience-dependent plasticity in the brain at the first levels of sensory processing (Edeline, J.-M., Weinberger, N.M., 1993. Behavioral Neuroscience 107, 82-103; Merzenich, M.M., Sameshima, K., 1993. Current Opinion in Neurobiology 3, 187-196; Weinberger, N.M., 1993. Current Opinion in Neurobiology 3, 577-579; Kraus, N., McGee, T., Carrel, T.D., King, C., Tremblay, K., Nicol, T., 1995. Journal of Cognitive Neuroscience 7 (1), 25-32). Outside of the laboratory, however, the situation seems to differ: we here report is study involving Spanish-Catalan bilingual subjects who have had the best opportunities to learn a new contrast but did not do it. Our study demonstrates a striking lack of behavioral plasticity: early and extensive exposure to a second language is not sufficient to attain the ultimate phonological competence of native speakers.

Analysis of Variance↗

PubMed1997

Native-language recognition abilities in 4-month-old infants from monolingual and bilingual environments.

This study examined the capacity of 4-month-old infants to identify their maternal language when phonologically similar languages are contrasted, using a visual orientation procedure with a reaction time measure. Infants from monolingual and bilingual environments were compared in order to analyze whether differences in linguistic background affect this behavioral response. In experiment 1 the validity of the procedure was assessed with a pair of phonologically dissimilar languages (Catalan or Spanish vs. English). In experiment 2, 20 infants from monolingual environments tested in a similar language contrast (Catalan vs. Spanish) indicated that discrimination is already possible at that age. Results from experiment 3, using low-pass filtered utterances, suggested that infants can rely on information about supra-segmental features to make this distinction. For the infants growing up in bilingual environments no preference for either of the familiar languages was found. Moreover, when their maternal language was contrasted either with English or with Italian, in both cases the bilingual group showed a similar pattern, consisting of significantly longer latencies for the familiar language. Possible interpretations of this unexpected pattern of results are discussed and its implications for bilingual language acquisition are considered.

Child Language↗

PubMedDate not supplied

[Dichotic listening test in Spanish: pairs of disyllabic words].

INTRODUCTION AND AIMS: Spanish dichotic listening tests make use of either monosyllabic words or single syllables. Here we present a dichotic listening test with 19 pairs of two-syllable words, since this type of words is more in accordance with the syllabic structure of the Spanish language. SUBJECTS AND METHODS: The test was applied to a total of 164 psychology students. Two studies were carried out--one exploratory and the other to obtain test-retest reliability. Responses were obtained with a distinction being made between four visual distractors. In the first study, up to two of the four alternatives could be chosen. In the second study, a single response was imposed and the test was performed twice with a gap of 15 days between sessions. RESULTS: Significant right ear advantage was observed both in the first study (t(39) = -9.57, p < 0.0001) and in the second (t(37) = -11.75, p < 0.0001). When the sample was separated into right-handed and left-handed subjects, significant differences between their medians were obtained in the first study with respect to the laterality index (t(14) = 2.23, p < 0.04). The test-retest correlation was found to be highly significant (r = 0.88, p < 0.0001). CONCLUSIONS: The present test appears to be a good indicator of laterality and we have implemented a computer program that allows us to modify the time intervals between pairs of stimuli and to obtain the laterality indexes automatically. Thus, the test can be used in a wide range of clinical populations.

Adult↗