Backward masking and asymmetry of processing for vowels differing in acoustical similarity

Several investigations have reported problems in demonstrating for vowels the phenomena of backward masking and right ear advantage so easily demonstrated for consonants. An experiment is reported on the dichotic backward masking (BM) of acoustically similar and dissimilar sets of vowels in consonant-vowel syllables. The results suggest that increasing perceptual difficulty by varying the acoustic similarity of the stimulus set augments BM. A second experiment showed that the right ear advantage (REA) was augmented by manipulating the acoustic similarity of the stimulus set and by decreasing intelligibility through the addition of noise. This and other evidence was employed to ascribe variations in both REA and BM to the interaction of perceptual processing time with information decay in precategorical acoustical storage. It is argued that this process interaction underlies statistical interactions in dichotic data which show that variations in difficulty (discriminability, noise addition, brain deterioration) affect most adversely the least favoured items (those presented earlier, those on the unattended ear, those on the left ear).     

Misreadings by beginning readers of Serbo-Croatian

Errors in reading aloud by the beginning reader have been interpreted as reflecting the difficulty and the importance of phonemic segmentation for the acquisition of reading skills. Results from previous studies on English words patterned as consonant-vowel-consonant showed: (1) more errors on vowels than on consonants; (2) more errors on word final consonants than on word initial consonants; and suggested that (3) consonant errors were based on phonetic confusions while vowel errors were not. In contrast to their English counterparts, the beginning readers of Serbo-Croatian tested in the present study committed proportionally fewer errors on their reading of vowels than of consonants but in common with their English counterparts, their reading of final consonants was more vulnerable to error than their reading of initial consonants. This pattern of errors was found for both word and pseudoword consonant-vowel-consonant structures and the pattern of vowel confusion, like the pattern of consonant confusions, was rationalized by speech-related factors. The differences between the patterns of confusions for Serbo-Croatian and for English could be due to the difference between the two orthographies in the precision with which they represent the phonology or to the fact that the vowels of English are qualitatively less distinct phonologically than the vowels of Serbo-Croatian.     

Prelexical phonological coding of visual words in Dutch: automatic after all

This paper addresses a previous claim (Brysbaert & Praet, 1992) that the use of prelexical phonology in visual word recognition is optional in the Dutch language. One backward masking experiment and two masked priming experiments are reported. The experimental task was perceptual identification. Pseudohomophones, graphemic controls, and unrelated controls of the target words were used as masks or primes. The main findings were (1) unlike previous claims, the pseudohomophone effect is not strategic in Dutch, but (2) the effect is more clearly obtained with the masked priming procedure than with the backward masking procedure.     

A recognition masking study of consonant processing

The processing of consonants was investigated in a series of experiments using a recognition masking paradigm. Experiment I investigated the effects of target duration, interstimulus interval, forward vs. backward masking, and the phonetic feature composition of the target and mask on accuracy of target identification. Experiment II assessed consonant processing when the target and mask were presented dichotically in order to separate central and peripheral components of consonant masking. Experiment III investigated the effects of mask duration on consonant processing. Substantial masking was found in backward and forward diotic and dichotic conditions. Evidence for target-mask interaction at the level of phonetic features was also found.     

Converging sources of evidence on spoken and perceived rhythms of speech: cyclic production of vowels in monosyllabic stress feet

The article reviews the literature from psychology, phonetics, and phonology bearing on production and perception of syllable timing in speech. A review of the psychological and phonetics literature suggests that production of vowels and consonants are interleaved in syllable sequences in such a way that vowel production is continuous or nearly so. Based on that literature, a hypothesis is developed concerning the perception of syllable timing assuming that vowel production is continuous. The hypothesis is that perceived syllable timing corresponds to the times sequencing of the vowels as produced and not to the timing either of vowel onsets as conventionally measured or of syllable-initial consonants. Three experiments support the hypothesis. One shows that information present during the portion of an acoustic signal in which a syllable-initial consonant predominates is used by listeners to identify the vowel. Compatibly, this information for the vowel contributes to the vowel's perceived duration. Finally, a measure of the perceived timing of a syllable correlates significantly with the time required to identify syllable-medial vowels but not with time to identify the syllable-initial consonants. Further support for the proposed mode of vowel-consonant production and perception is derived from the literature on phonology. Language-specific phonological conventions can be identified that may reflect exaggerations and conventionalizations of the articulatory tendency for vowels to be produced continuously in speech.     

Effect of consonant/vowel letter organisation on the syllable counting task: evidence from English

Recent studies in alphabetic writing systems have investigated whether the status of letters as consonants or vowels influences the perception and processing of written words. Here, we examined to what extent the organisation of consonants and vowels within words affects performance in a syllable counting task in English. Participants were asked to judge the number of syllables in written words that were matched for the number of spoken syllables but comprised either 1 orthographic vowel cluster less than the number of syllables (hiatus words, e.g., triumph) or as many vowel clusters as syllables (e.g., pudding). In 3 experiments, we found that readers were slower and less accurate on hiatus than control words, even when phonological complexity (Experiment 1), number of reduced vowels (Experiment 2), and number of letters (Experiment 3) were taken into account. Interestingly, for words with or without the same number of vowel clusters and syllables, participants’ errors were more likely to underestimate the number of syllables than to overestimate it. Results are discussed in a cross-linguistic perspective.     

Vowel mutability and lexical selection in English: Evidence from a word reconstruction task

Laboratoire de Sciences Cognitives et Psycholinguistique, Paris, France This study introduces a new paradigm for investigating lexical processing. First, an analysis of data from a series of word-spotting experiments is presented suggesting that listeners treat vowels as more mutable than consonants in auditory word recognition in English. In order to assess this hypothesis, a word reconstruction task was devised in which listeners were required to turn word-like nonwords into words by adapting the identity of either one vowel or one consonant. Listeners modified vowel identity more readily than consonant identity. Furthermore, incorrect responses more often involved a vowel change than a consonant change. These findings are compatible with the proposal that English listeners are equipped to deal with vowel variability by assuming that vowel identity is comparatively underdefined. The results are discussed in the light of theoretical accounts of speech processing.     

Testing the two-cycle model by different word types

The two-cycle model assumes that consonants in words are processed more quickly than vowels. This study tested the two-cycle model with different word types using a priming task which presented consonants or vowels before the target. Analysis showed presenting consonants before the target was beneficial in processing the target for the words with the letter compositions of CWC and CVCV. In contrast, presenting vowels before the target was beneficial for the words with the letter composition of VCVC. The words with the letter composition of VCCV showed no difference between the consonant prime and the vowel prime. The two-cycle model was not supported across all types of words.     

The processing of consonants and vowels during letter identity and letter position assignment in visual-word recognition: an ERP study

Recent research suggests that there is a processing distinction between consonants and vowels in visual-word recognition. Here we conjointly examine the time course of consonants and vowels in processes of letter identity and letter position assignment. Event related potentials (ERPs) were recorded while participants read words and pseudowords in a lexical decision task. The stimuli were displayed under different conditions in a masked priming paradigm with a 50-ms SOA: (i) identity/baseline condition e.g., chocolate-CHOCOLATE); (ii) vowels-delayed condition (e.g., choc_l_te-CHOCOLATE); (iii) consonants-delayed condition (cho_o_ate-CHOCOLATE); (iv) consonants-transposed condition (cholocate-CHOCOLATE); (v) vowels-transposed condition (chocalote-CHOCOLATE), and (vi) unrelated condition (editorial-CHOCOLATE). Results showed earlier ERP effects and longer reaction times for the delayed-letter compared to the transposed-letter conditions. Furthermore, at early stages of processing, consonants may play a greater role during letter identity processing. Differences between vowels and consonants regarding letter position assignment are discussed in terms of a later phonological level involved in lexical retrieval.     

Connectionist modelling of the separable processing of consonants and vowels

describe two aphasic patients, with impaired processing of vowels and consonants, respectively. The impairments could not be captured according to the sonority hierarchy or in terms of a feature level analysis. Caramazza et al. claim that this dissociation demonstrates separate representation of the categories of vowels and consonants in speech processing. We present two connectionist models of the management of phonological representations. The models spontaneously develop separable processing of vowels and consonants. The models have two hidden layers and are given as input vowels and consonants represented in terms of their phonological distinctive features. The first model is presented with feature bundles one at a time and the hidden layers have to combine their output to reproduce a unified copy of the feature bundle. In the second model a "fine-coded" layer receives information about feature bundles in isolation, and a "coarse-coded" layer receives information about each feature bundle in the context of the prior and subsequent feature bundle. Coarse-coding facilitated processing of vowels and fine-coding processing of consonants. These models show that separable processing of vowels and consonants is an emergent effect of modular processors operating on feature-based representations. We argue that it is not necessary to postulate an independent level of representation for the consonant/vowel distinction, separate from phonological distinctive features.     

Reading isolated words: No evidence for automatic incorporation of the phonetic code

Summary Backward masking with a homophonic mask induces better target recognition than backward masking with a graphemic mask that shares the same letters with the target as the homophonic mask. From this, the existence of automatic prelexical phonological recoding in silent word reading has been inferred. The present experiments, however, show that the advantage of homophonic masks in a backward-masking task only arises if a considerable proportion of the masks are phonologically related to the targets (at least for Dutch). The results are in line with findings of lexical-decision tasks and number-processing tasks, and constitute a further argument for the dominance of the orthographic route over the phonological route in processing isolated written words.     

Investigating linguistic relativity through bilingualism: the case of grammatical gender

The authors investigated linguistic relativity effects by examining the semantic effects of grammatical gender (present in Italian but absent in English) in fluent bilingual speakers as compared with monolingual speakers. In an error-induction experiment, they used responses by monolingual speakers to establish a baseline for bilingual speakers and show that gender affects the semantic substitution errors made by monolingual Italian speakers compared with monolingual English speakers. They then showed that Italian-English bilingual speakers behave like monolingual English speakers when the task is in English and like monolingual Italian speakers when the task is in Italian, hence exhibiting appropriate semantic representations for each language. These results show that for bilingual speakers there is intraspeaker relativity in semantic representations and, therefore, that gender does not have a conceptual, nonlinguistic effect. The results also have implications for models of bilingual semantic memory and processing.     

The relative position priming effect depends on whether letters are vowels or consonants

The relative position priming effect is a type of subset priming in which target word recognition is facilitated as a consequence of priming the word with some of its letters, maintaining their relative position (e.g., csn as a prime for casino). Five experiments were conducted to test whether vowel-only and consonant-only subset primes contribute equally to this effect. Experiment 1 revealed that this subset priming effect emerged when primes were composed exclusively of consonants, compared with vowel-only primes (csn-casino vs. aia-animal). Experiment 2 tested the impact of letter frequency in this asymmetry. Subset priming effects were obtained for both high- and low-frequency consonants but not for vowels, which rules out a letter frequency explanation. Experiment 3 tested the role of phonology and its contribution to the priming effects observed, by decreasing the prime duration. The results showed virtually the same effects as in the previous experiments. Finally, Experiments 4 and 5 explored the influence of repeated letters in the primes on the magnitude of the priming effects obtained for consonant and vowel subset primes (iuo-dibujo and aea-madera vs. mgn-imagen and rtr-frutero). Again, the results confirmed the priming asymmetry. We propose that a functional distinction between consonants and vowels, mainly based on the lexical constraints imposed by each of these types of letters, might provide an explanation for the whole set of results.     

Structural generalizations over consonants and vowels in 11-month-old infants

Recent research has suggested consonants and vowels serve different roles during language processing. While statistical computations are preferentially made over consonants but not over vowels, simple structural generalizations are easily made over vowels but not over consonants. Nevertheless, the origins of this asymmetry are unknown. Here we tested if a lifelong experience with language is necessary for vowels to become the preferred target for structural generalizations. We presented 11-month-old infants with a series of CVCVCV nonsense words in which all vowels were arranged according to an AAB rule (first and second vowels were the same, while the third vowel was different). During the test, we presented infants with new words whose vowels either followed or not, the aforementioned rule. We found that infants readily generalized this rule when implemented over the vowels. However, when the same rule was implemented over the consonants, infants could not generalize it to new instances. These results parallel those found with adult participants and demonstrate that several years of experience learning a language are not necessary for functional asymmetries between consonants and vowels to appear.     

The quest for generalizations over consonants: Asymmetries between consonants and vowels are not the by-product of acoustic differences

Consonants and vowels may play different roles during language processing, consonants being preferentially involved in lexical processing, and vowels tending to mark syntactic constituency through prosodic cues. In support of this view, artificial language learning studies have demonstrated that consonants (C) support statistical computations, whereas vowels (V) allow certain structural generalizations. Nevertheless, these asymmetries could be mere by-products of lower level acoustic differences between Cs and Vs, in particular the energy they carry, and thus their relative salience. Here we address this issue and show that vowels remain the preferred targets for generalizations, even when consonants are made highly salient or vowels barely audible. Participants listened to speech streams of nonsense CVCVCV words, in which consonants followed a simple ABA structure. Participants failed to generalize this structure over sonorant consonants (Experiment 1), even when vowel duration was reduced to one third of that of consonants (Experiment 2). When vowels were eliminated from the stream, participants showed only a marginal evidence of generalizations (Experiment 4). In contrast, participants readily generalized the structure over barely audible vowels (Experiment 3). These results show that different roles of consonants and vowels cannot be readily reduced to acoustical and perceptual differences between these phonetic categories.     

Vowel recognition: Inferences from studies of forward and backward masking

The recognition of brief vowels was studied in forward and backward masking tasks. In a series of experiments in which both target and mask parameters were systematically varied, two populations of subjects were identified. The majority (Nonmaskers) evidenced little masking at any interstimulus interval, while relatively fewer subjects (Maskers) evidenced backward masking (but not forward masking) over a 100-200 ms interval. Increasing target set size systematically increased masking for the Maskers but not for the Nonmaskers. Adding white noise to the targets increased the extent of masking for both groups. These results suggest (1) that masking does not impose a substantive constraint on vowel perception in running speech, and (2) that multiple strategies may exist for vowel recognition.     

Left-Hemisphere Advantage for Click Consonants is Determined by Linguistic Significance and Experience

Abstract—Left-hemisphere (LH) superiority for speech perception is a fundamental neurocognitive aspect of language, and is particularly strong for consonant perception. Two key theoretical aspects of the LH advantage for consonants remain controversial, however: the processing mode (auditory vs. linguistic) and the developmental basis of the specialization (innate vs. experience dependent). Click consonants offer a unique opportunity to evaluate these theoretical issues. Brief and spectrally complex, oral clicks exemplify the acoustic properties that have been proposed for an auditorily based LH specialization, yet they retain linguistic significance only for listeners whose languages employ them as consonants (e.g., Zulu). Speakers of other languages (e.g., English) perceive these clicks as nonspeech sounds. We assessed Zulu versus English listeners' hemispheric asymmetries for clicks, in and out of syllable context, in a dichotic-listening task. Performance was good for both groups, but only Zulus showed an LH advantage. Thus, linguistic processing and experience both appear to be crucial.