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PubMed1991

The mental representation of lexical form: a phonological approach to the recognition lexicon.

We propose a psycholinguistic model of lexical processing which incorporates both process and representation. The view of lexical access and selection that we advocate claims that these processes are conducted with respect to abstract underspecified phonological representations of lexical form. The abstract form of a given item in the recognition lexicon is an integrated segmental-featural representation, where all predictable and non-distinctive information is withheld. This means that listeners do not have available to them, as they process the speech input, a representation of the surface phonetic realisation of a given word-form. What determines performance is the abstract, underspecified representation with respect to which this surface string is being interpreted. These claims were tested by studying the interpretation of the same phonological feature, vowel nasality, in two languages, English and Bengali. The underlying status of this feature differs in the two languages; nasality is distinctive only in consonants in English, while both vowels and consonants contrast in nasality in Bengali. Both languages have an assimilation process which spreads nasality from a nasal consonant to the preceding vowel. A cross-linguistic gating study was conducted to investigate whether listeners would interpret nasal and oral vowels differently in two languages. The results show that surface phonetic nasality in the vowel in VN sequences is used by English listeners to anticipate the upcoming nasal consonant. In Bengali, however, nasality is initially interpreted as an underlying nasal vowel. Bengali listeners respond to CVN stimuli with words containing a nasal vowel, until they get information about the nasal consonant. In contrast, oral vowels in both languages are unspecified for nasality and are interpreted accordingly. Listeners in both languages respond with CVN words (which have phonetic nasality on the surface) as well as with CVC words while hearing an oral vowel. The results of this cross-linguistic study support, in detail, the hypothesis that the listener's interpretation of the speech input is in terms of an abstract underspecified representation of lexical form.

Concept Formation↗
PubMed1992

Some consequences of stimulus variability on speech processing by 2-month-old infants.

The present study explores how stimulus variability in speech production influences the 2-month-old infant's perception and memory for speech sounds. Experiment 1 focuses on the consequences of talker variability for the infant's ability to detect differences between speech sounds. When tested with high-amplitude sucking (HAS) procedure, infants who listened to versions of a syllable, such as [symbol: see text], produced by 6 male and 6 female talkers, detected a change to another syllable, such as [symbol: see text], uttered by the same group of talkers. In fact, infants exposed to multiple talkers performed as well as other infants who heard utterances produced by only a single talker. Moreover, other results showed that infants discriminate the voices of the individual talkers, although discriminating one mixed group of talkers (3 males and 3 females) from another is too difficult for them. Experiment 2 explored the consequences of talker variability on infants' memory for speech sounds. The HAS procedure was modified by introducing a 2-min delay period between the familiarization and test phases of the experiment. Talker variability impeded infants' encoding of speech sounds. Infants who heard versions of the same syllable produced by 12 different talkers did not detect a change to a new syllable produced by the same talkers after the delay period. However, infants who heard the same syllable produced by a single talker were able to detect the phonetic change after the delay. Finally, although infants who heard productions from a single talker retained information about the phonetic structure of the syllable during the delay, they apparently did not retain information about the identity of the talker. Experiment 3 reduced the range of variability across talkers and investigated whether variability interferes with retention of all speech information. Although reducing the range of variability did not lead to retention of phonetic details, infants did recognize a change in the gender of the talkers' voices (from male to female or vice versa) after a 2-min delay. Two additional experiments explored the consequences of limiting the variability to a single talker. In Experiment 4, with an immediate testing procedure, infants exposed to 12 different tokens of one syllable produced by the same talker discriminated these from 12 tokens of another syllable.(ABSTRACT TRUNCATED AT 400 WORDS)

Arousal↗
PubMed1994

The effect of subphonetic differences on lexical access.

This study investigated whether lexical access is affected by inherent acoustic variations that contribute to the identity of a phonetic feature and ultimately a phonetic segment. Two experiments were conducted to determine whether the magnitude of semantic (associative) priming in a lexical decision task is influenced when the acoustic manifestation of the initial voiceless stop consonant (specifically, voice onset time) of a prime word semantically related to a lexical decision target was systematically manipulated (e.g., prime: "king"; target: "queen"). Results showed no effect of the acoustic manipulations at the longer interstimulus interval (250 ms); however, at the shorter interstimulus interval (50 ms), the magnitude of semantic facilitation decreased as a function of the voice onset time manipulations. In addition, there was a tendency toward slower lexical decision latencies when the prime word had a real word voiced counterpart than when it did not. These results suggest that activation levels of words in the lexicon are graded, depending on the subphonetic shape of the input word. Results also suggest that words which are phonologically similar to the intended word candidate are activated to some extent, whether the input provides a relatively poor phonetic representation of the intended word or a good one.

Humans↗
PubMed1984

Trading relations in the perception of speech by 5-year-old children.

Five-year-old children were tested for perceptual trading relations between a temporal cue (silence duration) and a spectral cue (F1 onset frequency) for the "say-stay" distinction. Identification functions were obtained for two synthetic "say-stay" continua, each containing systematic variations in the amount of silence following the /s/ noise. In one continuum, the vocalic portion had a lower F1 onset than in the other continuum. Children showed a smaller trading relation than has been found with adults. They did not differ from adults, however, in their perception of an "ay-day" continuum formed by varying F1 onset frequency only. The results of a discrimination task in which the two acoustic cues were made to "cooperate" or "conflict" phonetically supported the notion of perceptual equivalence of the temporal and spectral cues along a single phonetic dimension. The results indicate that young children, like adults, perceptually integrate multiple cues to a speech contrast in a phonetically relevant manner, but that they may not give the same perceptual weights to the various cues as do adults.

Child Development↗
PubMed1990

Temporal dimensions of consonant and vowel production: an acoustic and CT scan analysis of aphasic speech.

This study explored a number of temporal (durational) parameters of consonant and vowel production in order to determine whether the speech production impairments of aphasics are the result of the same or different underlying mechanisms and in particular whether they implicate deficits that are primarily phonetic or phonological in nature. Detailed analyses of CT scan lesion data were also conducted to explore whether more specific neuroanatomical correlations could be made with speech production deficits. A series of acoustic analyses were conducted including voice-onset time, intrinsic and contrastive fricative duration, and intrinsic and contrastive vowel duration as produced by Broca's aphasics with anterior lesions (A patients), nonfluent aphasics with anterior and posterior lesions (AP patients), and fluent aphasics with posterior lesions (P patients). The constellation of impairments for the anterior aphasics including both the A and AP patients suggests that their disorder primarily reflects an inability to implement particular types of articulatory gestures or articulatory parameters rather than an inability to implement particular phonetic features. They display impairments in the implementation of laryngeal gestures for both consonant and vowel production. These patterns seem to relate to particular anatomical sites involving Broca's area, the anterior limb of the internal capsule, and the lowest motor cortex areas for larynx and tongue. The posterior patients also show evidence of subtle phonetic impairments suggesting that the neural instantiation of speech may require more extensive involvement, including the perisylvian area, than previously suggested.

Aged↗
PubMed2006

Phonemic restoration in a sentence context: evidence from early and late ERP effects.

When a particular speech sound is obliterated and replaced by a non-speech sound in continuous speech the listener may not notice any disturbance in speech or have difficulties in understanding the word. The present study examined for the first time neurophysiological correlates of the perception of words with an obliterated initial phoneme. Behavioral responses and event-related potentials (ERPs) were measured while participants listened to naturally spoken sentences which had a highly or less expected final word. Half of the sentences were manipulated to have a cough replacing the beginning of the final word, thus, reducing the initial phonetic information available for the word recognition. An N1-P2 complex indicated an automatic registration of the cough's onset. An early negativity to less expected relative to highly expected words was observed for phonetically intact words but not for manipulated words. Although the N400 effect to manipulated words was elicited later than to intact words, after the fragment onset, its amplitude was not enhanced. Further, no significant enhancement of the N400 was found for the manipulated highly expected words. This finding, together with behavioral results, indicated an easier integration of the manipulated highly expected words with the sentence context than of intact but less expected words. Taken together, the study demonstrates an efficient usage of both a context-driven expectancy of the suitable word as well as a stimulus-driven processing of the phonetic information during online perception of speech. The present ERP results support the earlier behavioral research in showing that phonemic restoration is not a bottom-up phenomenon but rather reflects a top-down repair process.

Acoustic Stimulation↗
PubMed2005

Effects of syllable frequency in speech production.

In the speech production model proposed by [Levelt, W. J. M., Roelofs, A., Meyer, A. S. (1999). A theory of lexical access in speech production. Behavioral and Brain Sciences, 22, pp. 1-75.], syllables play a crucial role at the interface of phonological and phonetic encoding. At this interface, abstract phonological syllables are translated into phonetic syllables. It is assumed that this translation process is mediated by a so-called Mental Syllabary. Rather than constructing the motor programs for each syllable on-line, the mental syllabary is hypothesized to provide pre-compiled gestural scores for the articulators. In order to find evidence for such a repository, we investigated syllable-frequency effects: If the mental syllabary consists of retrievable representations corresponding to syllables, then the retrieval process should be sensitive to frequency differences. In a series of experiments using a symbol-position association learning task, we tested whether high-frequency syllables are retrieved and produced faster compared to low-frequency syllables. We found significant syllable frequency effects with monosyllabic pseudo-words and disyllabic pseudo-words in which the first syllable bore the frequency manipulation; no effect was found when the frequency manipulation was on the second syllable. The implications of these results for the theory of word form encoding at the interface of phonological and phonetic encoding; especially with respect to the access mechanisms to the mental syllabary in the speech production model by (Levelt et al.) are discussed.

Humans↗
PubMed2006

What we know about what we have never heard: evidence from perceptual illusions.

Are speakers equipped with preferences concerning grammatical structures that are absent in their language? We examine this question by investigating the sensitivity of English speakers to the sonority of onset clusters. Linguistic research suggests that certain onset clusters are universally preferred (e.g., bd>lb). We demonstrate that such preferences modulate the perception of unattested onsets by English speakers: Monosyllabic auditory nonwords with onsets that are universally dispreferred (e.g., lbif) are more likely to be classified as disyllabic and misperceived as identical to their disyllabic counterparts (e.g., lebif) compared to onsets that are relatively preferred across languages (e.g., bdif). Consequently, dispreferred onsets benefit from priming by their epenthetic counterpart (e.g., lebif-lbif) as much as they benefit from identity priming (e.g., lbif-lbif). A similar pattern of misperception (e.g., lbif-->lebif) was observed among speakers of Russian, where clusters of this type occur. But unlike English speakers, Russian speakers perceived these clusters accurately on most trials, suggesting that the perceptual illusions of English speakers are partly due to their linguistic experience, rather than phonetic confusion alone. Further evidence against a purely phonetic explanation for our results is offered by the capacity of English speakers to perceive such onsets accurately under conditions that encourage precise phonetic encoding. The perceptual illusions of English speakers are also irreducible to several statistical properties of the English lexicon. The systematic misperception of universally dispreferred onsets might reflect their ill-formedness in the grammars of all speakers, irrespective of linguistic experience. Such universal grammatical preferences implicate constraints on language learning.

Auditory Perception↗
PubMed1999

Continuous processing in word recognition at 24 months.

Speech processing in adults in continuous: as acoustic-phonetic information is heard, listeners' interpretation of the speech is updated incrementally. The present studies used a visual fixation technique to examine whether young children also interpret speech continuously. In Experiments 1 and 2, 24-month-old children looked at visual displays while hearing sentences. Sentences each contained a target word labeling one of the two displayed pictures. Children's latency to fixate the labeled picture was measured. Children's responses were delayed when the competing distractor picture's label overlapped phonetically with the target at onset (dog-doll), but not when the pictures' labels rhymed (ball-doll), showing that children monitored the speech stream incrementally for acoustic-phonetic information specifying the correct picture. In Experiment 3, adults' responses in the same task were found to be very similar to those of the 24-month-olds. This research shows that by 24 months, children can interpret speech continuously.

Adult↗
PubMed1981

The relationship between type of naming error and semantic-lexical discrimination in aphasic patients.

When submitted to confrontation naming tasks, aphasic patients show different types of naming errors: phonetic, phonemic and verbal-semantic paraphasias, neologisms and anomia, but it is generally difficult to decide whether these errors are mainly due to a breakdown of the semantic systems or to post-lexical phonological disorders. In order to clarify this issue, 118 aphasic patients were given 3 tests of confrontation naming and 3 tests of semantic-lexical discrimination. Naming errors on confrontation were used to classify aphasic patients in various subgroups (according to the prevalence of a given type of naming error), whereas performances obtained on tests of semantic-lexical discrimination were taken as an index of disorganization of the semantic systems. The performances on semantic discrimination tests of patients showing a prevalence of phonetic, phonemic and verbal-semantic paraphasias, neologisms and anomia on confrontation naming tasks were compared. A very small number of semantic discrimination errors was obtained by patients showing a prevalence of phonetic and phonemic transformations on confrontation, whereas a much larger number of semantic discrimination errors was obtained by patients showing a prevalence of verbal-semantic paraphasias, neologisms and anomia.

Anomia↗
PubMed2001

Exploration of hemispheric specialization and lexico-semantic processing in unilateral temporal lobe epilepsy with verbal fluency tasks.

Verbal production has been shown to rely on both hemispheres differentially. To determine how lateralized brain lesions affect the generation of isolated words, we evaluated three subject groups: normal controls (n=22), and patients with right (n=23), and left (n=22) non-operated temporal lobe epilepsy (TLE) using three verbal fluency tasks (letter, phonetic, semantic). LTLE patients produced fewer words than controls in the phonetic, letter, semantic conditions, whereas RTLE patients were only impaired in the semantic task. Hence, there would be a hemispheric specialization in language where phonetic processing involves mostly the left temporal lobe and semantic aspects of production involve both temporal lobes. And, in order to study disruption of semantic lexicon involved in supermarket fluency (to name things which can be bought in a supermarket), specific indicators Tröster et al., (1998) [Tröster AI, Fields JA, Testa JA, Paul RH, Blanco CR, Hames KA, Salmon DP, Beatty WW. Cortical and subcortical influences on clustering and switching in the performance of verbal fluency Tasks, Neuropsychologia 1998;36:295-304.] were exploited. Our results indicated that TLE groups made fewer category shifts than controls. Also, RTLE patients used labels more frequently and produced fewer exemplars. Results show the specificity of processing according to cue, and suggest that the semantic fluency deficits due to TLE be primarily due to an alteration of the mental lexicon.

Adult↗
PubMed2004

Levels of processing with free and cued recall and unilateral temporal lobe epilepsy.

This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.

Adult↗
PubMed2003

Neural substrates of impaired categorical perception of phonemes in adult dyslexics: an fMRI study.

Phonological developmental dyslexics remain impaired in phonetic categorical perception (CP) even in adulthood. We studied the brain correlates of CP in dyslexics and controls using a block design fMRI protocol and stimuli from an phonetic continuum between natural /Pa/ and /Ta/ syllables. Subjects performed a pseudo-passive listening task which does not imply voluntary categorical judgment. In the control group, categorical deviant stimuli elicited specific activations in the left angular gyrus, the right inferior frontal gyrus and the right superior cingulate cortex. These regions were not activated in the dyslexic group in which activation was observed for acoustic but not phonetic changes in stimuli. Failures to activate key regions for language perception and auditory attention in dyslexic might account for persistent deficits in phonological awareness and reading tasks.

Adult↗
PubMed1999

[Test construction, analysis and trial of the Heidelberg Sound Discrimination Test for measuring auditory-kinesthetic perceptual discrimination acuity].

The provisional trial was carried out in a sample of 133 second- and 139 fourth-graders from the Heidelberg area. The HD-LT was subjected to an item selection, test criteria were ascertained and temporary percentile norms for the second and fourth grades were established. High item difficulty resulted for both grades, i.e. the test was relatively easy. Test criteria were generally satisfactory. Significant correlations were found in both grades between the HD-LT and the children's spelling ability. The HD-LT accounted for 30% of the spelling variance among second-graders as compared to 10% of that among fourth-graders. This reflects the specific significance of phonetic discrimination ability in the first years of elementary school. Children with spelling difficulties were compared to those with good spelling abilities in respect to their ability to discriminate sound. Spelling-impaired children in both grades exhibited a significantly lower overall HD-LT score. No significant sex differences were found with regard to the auditory and kinesthetic phonetic discrimination ability. Since the HD-LT turns out to be well-suited to indicate a phonetic discrimination disability during the initial phases of acquisition of written language, its further development and extension of its application to the pre-school level are recommended.

Child↗
PubMed1985

Perceptual coherence of speech: stability of silence-cued stop consonants.

A series of experiments was conducted to examine the perceptual stability of stop consonants cued by silence alone, as when [s] + silence + [laet] is perceived as splat. Following a replication of this perceptual integration phenomenon (Experiment 1), attempts were made to block it by instructing subjects to disregard the initial [s] and to focus instead on the onset of the following signal, which was varied from [plaet] to [laet]. However, these instructions had little effect at short silence durations (Experiment 2), and they reduced stop percepts for only 2 subjects at longer silence durations (Experiment 3). That is, subjects were generally unable to voluntarily dissociate the [s] noise from the following signal and thus to perceive the silent interval as silence rather than as a carrier of phonetic information. A low-uncertainty paradigm facilitated the task somewhat (Experiment 4). However, when the [s] frication was replaced with broadband noise (Experiment 5), listeners had no trouble at all in the selective-attention task, except at very short silence durations (less than 40 ms). This last finding suggests that, except for the shortest durations, the effect of silence on phonetic perception does not arise at the level of psychoacoustic stimulus interactions. Rather, the results support the hypothesis that perceptual integration of speech components, including silence, is a largely obligatory perceptual function driven by the listener's tacit knowledge of phonetic regularities.

Attention↗
PubMed1981

Adaptation and contrast in the perception of voicing.

The results of experiments using selective adaptation with stop consonants have been interpreted in terms of auditory feature detector fatigue, phonetic feature detector fatigue, and response contrast. In the present studies, both a selective adaptation procedure and a procedure involving paired comparisons between successively presented stimuli were used to sort out these explanations. A fricative-stop-vowel syllable ([spa]) was constructed using an [s], followed by 75 msec of silence, followed by a 10-msec voice onset time [ba]. The perceived phonetic identity of this syllable was [p] even though the spectral structure of the stop vowel within this syllable was identical to a stimulus from the [ba] end of a [ba]-[pha] test series. As adaptors, the [spa] and [ba] endpoint syllables had identical effects. In paired-comparison procedure, the [spa] caused an ambiguous test item to be labeled "B," whereas the [ba] caused the test item to be labeled "P." Results of these experiments indicate that neither response contrast nor phonetic feature detection are involved in selective adaptation effects found for a voicing stop-consonant series. Results are interpreted as supporting the position that selective adaptation effects arise at an early, auditory level of processing that is responsive to the spectral overlap between adaptor and test items.

Discrimination Learning↗
PubMed1988

An investigation of young infants' perceptual representations of speech sounds.

The present study examined the ability of newborns and 2-month-olds to detect phonetic differences between syllables. By relying on the modified high-amplitude sucking procedure, which did not permit the infants to use a simple same-different response, the present experiments tapped the perceptual representations of the speech sounds. Infants as young as a few days old displayed some capacity to represent differences in a set of syllables varying in their phonetic composition, although there was no convincing evidence that their representations were structured in terms of phonetic segments. Finally, evidence of developmental changes in speech processing were noted for the first time with infants in this age range. The change noted was a tendency from global toward more specific representations on the part of the older infants.

Arousal↗
PubMed1997

The role of component function in visual recognition of Chinese characters.

M. Taft and X. Zhu (1997) reported that character decision latencies to real Chinese characters containing components that entered into many combinations were faster than decision latencies to characters with components that entered into only a small number of combinations. However, this effect was restricted to components that appeared on the right side of Chinese characters. In written Chinese, phonetic components tend to appear on the right, and semantic components tend to appear on the left. Therefore, in Taft and Zhu's study, there was the possibility of a confound between position (left vs. right) and function (semantic vs. phonetic). Results of the present experiment show combinability effects for components with semantic and with phonetic functions. Counter to the claim by Taft and Zhu that component frequency effects are constrained by position, when component function was considered, character decision latencies varied with component frequency but not reliably with position.

Adult↗