Enhanced discriminability at the phonetic boundaries for the voicing feature in macaques

Discrimination of speech sounds from three computer-generated continua that ranged from voiced to voiceless syllables (/ba-pa/, /da-ta/, and ga-ha/ was tested with three macaques. The stimuli on each continuum varied in voice-onset time (VOT). Paris of stimuli that were equally different in VOT were chosen such that they were either within-category pairs (syllables given the same phonetic label by human listeners) or between-category paks (syllables given different phonetic labels by human listeners). Results demonstrated that discrimination performance was always best for between-category pairs of stimuli, thus replicating the “phoneme boundary effect” seen in adult listeners and in human infants as young as I month of age. The findings are discussed in terms of their specific impact on accounts of voicing perception in human listeners and in terms of their impact on discussions of the evolution of language.     

Acoustic cues and psychological processes in the perception of natural stop consonants

These studies examined the perceptual role of various components of naturally produced stop consonants (/b, d, g, p, t, k/) in CV syllables. In the first experiment, the context-sensitive voiced formant transitions were removed with a computer-splicing technique. Identification accuracy was 84% when the consonant was presented with the same vowel as had been used to produce it. Performance fell to 66% when the consonant was juxtaposed with a different vowel. The second experiment not only deleted the voiced formant transition, but also replaced the aspiration with silence. Here, identification accuracy dropped substantially, especially for voiceless stops, which had contained devoiced formant transitions in the replaced interval. The pattern of errors suggested that listeners try to extract the missing locus of the consonant from the vowel transition, and in the absence of a vowel transition, they try to extrapolate it from the second formant of the steady-state vowel.     

Phoneme‐Order Encoding During Spoken Word Recognition: A Priming Investigation

In three experiments, we examined priming effects where primes were formed by transposing the first and last phoneme of tri‐phonemic target words (e.g., /byt/ as a prime for /tyb/). Auditory lexical decisions were found not to be sensitive to this transposed‐phoneme priming manipulation in long‐term priming (Experiment 1), with primes and targets presented in two separated blocks of stimuli and with unrelated primes used as control condition (/mul/‐/tyb/), while a long‐term repetition priming effect was observed (/tyb/‐/tyb/). However, a clear transposed‐phoneme priming effect was found in two short‐term priming experiments (Experiments 2 and 3), with primes and targets presented in close temporal succession. The transposed‐phoneme priming effect was found when unrelated prime‐target pairs (/mul/‐/tyb/) were used as control and more important when prime‐target pairs sharing the medial vowel (/pys/‐/tyb/) served as control condition, thus indicating that the effect is not due to vocalic overlap. Finally, in Experiment 3, a transposed‐phoneme priming effect was found when primes sharing the medial vowel plus one consonant in an incorrect position with the targets (/byl/‐/tyb/) served as control condition, and this condition did not differ significantly from the vowel‐only condition. Altogether, these results provide further evidence for a role for position‐independent phonemes in spoken word recognition, such that a phoneme at a given position in a word also provides evidence for the presence of words that contain that phoneme at a different position.     

Does Talker‐Specific Information Influence Lexical Competition? Evidence From Phonological Priming

In this study, we examined whether the lexical competition process embraced by most models of spoken word recognition is sensitive to talker‐specific information. We used a lexical decision task and a long lag priming experiment in which primes and targets sharing all phonemes except the last one (e.g., /bagaR/“fight” vs. /baga?/“luggage”) were presented in two separate blocks of stimuli. In Experiment 1, the competitor prime block was presented only once to listeners, and no modulation of the competitor priming effect as a function of a talker change between the primes and targets was observed. However, attenuation in the competitor priming effect in the case of a talker change between the primes and targets was observed in Experiment 2 in which the competitor prime block was presented five times to listeners. We discuss our findings in reference to hybrid models of spoken word recognition in which repetition of words with the same talker could be a key factor in the formation and access to talker‐dependent representations.     

辅音和元音知觉中的启动效应差异

采用启动范式,在两个实验中分别考察了辅音范畴和元音范畴知觉中的启动效应。启动音是纯音和目标范畴本身,目标音是辅音范畴和元音范畴连续体。结果发现辅音范畴连续体知觉的范畴反应百分比受到纯音和言语启动音影响,辅音范畴知觉的反应时只受言语启动音影响;元音范畴连续体知觉的范畴反应百分比不受两种启动音影响,但元音范畴知觉的反应时受到言语启动音影响。实验结果表明辅音范畴和元音范畴知觉中的启动效应存在差异,这为辅音和元音范畴内在加工机制的差异提供了新证据。     

Central and peripheral representation of whispered and voiced speech

Whispered speech is very different acoustically from normally voiced speech, yet listeners appear to have little trouble perceiving whispered speech. Two selective adaptation experiments explored the basis for the common perception of whispered and voiced speech, using two synthetic /ba/-/wa/ continua (one voiced, and one whispered). In the first experiment the endpoints of each series were used as adaptors, along with several nonspeech adaptors. Speech adaptors produced reliable labeling shifts of syllables matching in periodicity (i.e., whispered-whispered or voiced-voiced); somewhat smaller effects were found with mismatched periodicity. A periodic nonspeech tone with short rise time (the "pluck") produced adaptation effects like those for /ba/. These shifts occurred for whispered test syllables as well as voiced ones, indicating a common abstract level of representation for voiced and whispered stimuli. Experiment 2 replicated and extended Experiment 1, using same-ear and cross-ear adaptation conditions. There was perfect cross-ear transfer of the nonspeech adaptation effect, again implicating an abstract level of representation. The results support the existence of two levels of processing for complex acoustic signals. The commonality of whispered and voiced speech arises at the second, abstract level. Both this level, and the earlier, more directly acoustic level, are susceptible to adaptation effects.     

The nature of speech production impairments in anterior aphasics: an acoustic analysis of voicing in fricative consonants

This study investigated the acoustic characteristics of voicing in English fricative consonants produced by anterior aphasics and the effects of phonetic context on these characteristics. Three patients produced voiced and voiceless fricative-vowel syllables in isolation, following a voiced velar stop, and following a voiceless velar stop. Acoustic analyses were conducted of the amplitude and patterning of glottal excitation, as well as fricative noise duration. Results showed that, although the patients are able to coordinate the articulatory gestures for voicing in fricative consonants, they demonstrated abnormal patterns of glottal excitation in the amplitude measures, owing to weaker amplitudes of glottal excitation in voiced fricatives. Context effects failed to emerge because of dysfluent speech. These results suggest that the locus of the speech production deficit of anterior aphasics is not at the higher stages of phoneme selection or planning but rather in articulatory implementation, one related to laryngeal control.     

Acoustic feature analysis in the perception of voicing contrasts

Various types of acoustic cues have been shown to signal voicing contrasts in initial prestressed stop consonants. Two of the most important of these cues are the time interval between the release burst and the onset of voicing (voice onset time) and the duration of voiced transitions. In the present experiment, a selective adaptation procedure was used to investigate possible feature extraction mechanisms which underlie the perception of voicing. Subjects first identified either of two series of test stimuli, [ba-p^ha) or [ga-k^ha]. Next they listened to repeated presentations of an adapting stimulus and then again identified the original test series. Adapting stimuli having the same value of voice onset time but different voiced transition durations produced differential (and sometimes opposite) effects on the identification of the test stimuli. In every case, the adapting stimulus with the greater duration of voiced transitions led to larger reduction in voiced responses or to a smaller increase in voiceless responses. These results are incompatible with models of voicing perception based strictly on detectors for voice onset time. The results also suggest that the adaptation effect occurs at a point in the system prior to the actual phonetic decision.     

Le rattachement lexical de la liaison : une expérience d’amorçage chez des enfants prélecteurs

The goal of the present study is a better understanding of the mechanisms involved in child segmentation of words in liaison context, where the boundary between a word1 and a word2 is ambiguous. In a priming experiment in prereaders aged 5–6 years, we examined the nature of the lexical representations, using a picture-naming task (deux ours). Targets were preceded by lexically related or unrelated auditory primes, that share the same liaison consonant or not (trois ours, un ours, trois oublis, un oubli). The results suggest that the liaison consonant is lexically encoded at the initial of variants of the word2 (/nurs/, /zurs/ for ours). They support the usage-based model of liaison acquisition [J Child Lang 36 (2009) 557–596].     

Competition Effects in Phonological Priming: The Role of Mismatch Position between Primes and Targets

In three experiments, we examined lexical competition effects using the phonological priming paradigm in a shadowing task. Experiments 1A and 1B showed that an inhibitory priming effect occurred when the primes mismatched the targets on the last phoneme (/bagar/–/bagaj/). In contrast, a facilitatory priming effect was observed when the primes mismatched the targets on the medial phoneme (/viraj/-/vilaj/). Experiment 2 replicated these findings with primes presented visually rather than auditorily. The data thus indicate that the position of the mismatching phoneme is a critical factor in determining the competition effect between prime and target words.     

Some articulatory correlates of perceptual isochrony

Given sequences of digits with temporally equidistant acoustic onsets, listeners do not perceive them as isochronous (Morton, Marcus, & Frankish, 1976). In order for the sequences to be perceptually isochronous, systematic departures from acoustic isochrony must be introduced. These acoustic departures are precisely those that talkers generate when asked to produce an isochronous sequence (Fowler, 1979), suggesting that listeners judge isochrony based on acoustic information about articulatory timing. The present experiment was an attempt to test directly whether perceptually isochronous sequences have isochronous articulatory correlates. Electromyographic potentials were recorded from the orbicularis oris muscle when speakers produced sequences of monosyllables “as if speaking in time to a metronome.” Sequences were devised so that lip-muscle activity was related to the syllable-initial consonant, the stressed vowel, or the stressed vowel and final consonant. Results indicate that isochronous muscular activity accompanies both isochronous and anisochronous acoustic signals produced under instructions to generate isochronous sequences. These results support an interpretation of the perceptual phenomenon reported by Morton et al. to the effect that listeners judge isochrony of the talker’s articulations as they are reflected in the acoustic signal.     

Perception Abilities of L1 Cypriot Greek Listeners - Types of Errors Involving Plosive Consonants in L2 English

This paper investigates the difficulties adult second language (L2) users of English encounter with plosive consonants in the L2. It presents the results of a task examining the acquisition of plosive voicing contrasts by college students with Cypriot Greek (CG) linguistic background. The task focused on the types of errors involving plosive consonants indicating that performance was significantly better in the voiceless plosive category. Participants were able to perceive voiced plosives but they treated such instances as a /nasal + voiced plosive/ sequence. Therefore, the question raised concerns different phonological contrasts realised through similar phonetic cues. The patterns observed suggested that this gap between phonetic cues and phonological contrast might explain why CG users have difficulties perceiving voiced English plosives. In this context, voice onset time (VOT) differences between the L1 and L2 are of crucial importance. In English, voiced plosives are characterised by short lag VOT while their voiceless counterparts fall within the long lag VOT continuum. The same phonetic contrast is used in CG to differentiate between single and geminate voiceless plosives. The results are discussed in relation to the frameworks of second language phonology and speech perception suggesting that the difficulties faced by the L2 listeners support the operation of a phonetic-phonological challenge.     

Fundamental frequency as a cue to postvocalic consonantal voicing: Some data from speech perception and production

Several recent studies by Lehiste have reported that changes in fundamental frequency (F0) can serve as a cue to perceived vowel length and, furthermore, that the perceived lengthening of the vowel can influence perception of the voicing feature of stop consonants in syllable-final position. In Experiment 1, we replicated Lehiste’s basic results for stop consonants in final position. Experiment 2 extended these results to postvocalic fricatives. The final consonant in syllables of intermediate vowel duration was more often perceived as voiced when F0 was falling than when F0 was monotone. In Experiment 3, we examined the F0 contours produced by eight talkers before postvocalic stop consonants and fricatives in natural speech for minimal pairs of words differing in voicing. The amount of change of F0 over the vowel was no greater before voiced than voiceless consonants, suggesting that the earlier perceptual effects cannot be explained by appealing to regularities observed in the production of F0 contours in vowels preceding postvocalic consonants.     

Perception of voicing and place features in whispered speech: A dichotic choice analysis

To offset shortcomings of existing demonstrations of right-ear superiority in the analysis of formant transitions, an experiment was performed on whispered speech. Two aspects of dichotic listening performance were examined in a single-report paradigm: the right-ear advantage (REA) for the perception of the voicing distinction and the feature sharing advantage (FSA) for both voicing and place features. A significant REA was obtained for the voicing distinction cued by first formant transition in the absence of a switch from aperiodic to periodic excitation. This, plus a greater incidence of voiced responses to right-ear stimuli, suggests that a distinction involving transitions can specifically augment the REA. The data also showed better identification of place and of voicing feature values when the competing dichotic speech stimuli shared these respective features (FSA) than when they did not. This FSA was restricted to the feature shared and hence not an effect of response uncertainty. The implications of these results for models of speech processing are discussed.     

Temporal coordination of phonation and articulation in a case of verbal apraxia: A voice onset time study

A study of voice onset time (VOT) in stop production was undertaken in order to investigate the hypothesis that the voicing feature errors in the speech of an apraxic patient (Sands, E. S., Freeman, F. J., & Harris, K. S. 1978. Brain and Language, 6, 97–105) were related to deficits in temporal coordination of phonation and articulation. Results demonstrated that the VOTs of the apraxic subject differed markedly from those of normal subjects. The apraxic productions did not include voicing lead for voiced stops. Lag times for voiced stops were longer than normal, while those for voiceless stops were shorter than normal, yielding a compression of the two categories and a marked overlap.     

The effect of depressed mood on the interpretation of ambiguity,with and without negative mood induction

Is there an effect of depressed mood on the interpretation of ambiguity? Are depressed individuals biased to interpret ambiguous information in a negative manner? We used a cross-modal semantic priming task to look for evidence of a negative interpretative bias. Participants listened to ambiguous prime sentences (e.g., Joan was stunned by her final exam mark) and made lexical decisions to target words presented immediately after the sentence offset or after a delay of 1000 ms or 2000 ms. For the semantically related targets, the target was negatively related (distress), positively related (success), or neutrally related (grades) to the ambiguous prime. The experiment was conducted with and without a negative mood induction. The expectation was that depressed participants would be more likely to consider the negative interpretations of the ambiguous primes and would therefore experience larger priming effects for negatively related targets. Although there were large priming effects for all semantically related targets, there was no evidence of a negative interpretative bias.     

Semantic transparency and masked morphological priming: The case of prefixed words

In four lexical decision experiments, we investigated masked morphological priming with Dutch prefixed words. Reliable effects of morphological relatedness were obtained with visual primes and visual targets in the absence of effects due to pure form overlap. In certain conditions, priming effects were significantly greater with semantically transparent prefixed primes (e.g., rename-name) relative to the priming effects obtained with semantically opaque prefixed words (e.g., relate-late), even with very brief (40-msec) prime durations. With visual primes and auditory targets (cross-modal priming), significant facilitation was found in all related prime conditions, independent of whether or not primes were morphologically related to targets. The results are interpreted within a bimodal hierarchical model of word recognition in which morphological effects arise through the interplay of sublexical (morpho-orthographic) and supralexical (morpho-semantic) representations. The word stimuli from this study may be downloaded as supplemental materials from http://mc.psychonomic-journals .org/content/supplemental.     

The Adams and Reis observations revisited

This experiment was designed as a replication of the Adams and Reis (1971, 1974) experiments, which posited a direct relationship between frequency of stuttering and the number of “off-on” laryngeal adjustments during speech. Twenty adult stutterers read two prose passages equivalent in length, word length, and semantic content. The first passage contained a normal distribution of syllable-initial voiced and voiceless consonants whereas the second contained only voiced phonemes. The results demonstrated significantly greater stuttering during reading of the all-voiced passage (P?0.05). These results did not confirm the earlier observations of Adams and Reis and mitigate the hypothesized relationships between stuttering frequency and “off-on” laryngeal adjustments.     

Some properties of linguistic feature detectors

A series of experiments, using a selective adaptation procedure, investigated some of the properties of the linguistic feature detectors that mediate the perception of the voiced and voiceless stop consonants. The first experiment showed that these detectors are centrally rather than peripherally located, in that monotic presentation of the adapting stimulus and test stimuli to different ears resulted in large and reliable shifts in the locus of the phonetic boundary. The second experiment revealed that the detectors are part of the specialized speech processor, inasmuch as adaptation of a voicing detector (as measured by a shift in the phonetic boundary) occurred only when the voicing information was presented in a speech context. In the third experiment, the detector mediating perception of the voiced stops was shown to be more resistant to adaptation than the detector mediating perception of the voiceless stops.     

The Influence of Masked Stimuli on Response Selection: Evidence from a Semantic Categorization Task

Unconscious visual stimuli can be processed by human observers and influence their behaviour. A striking example is a phenomenon known as “free-choice priming,” where masked “prime” stimuli—of which participants are unaware—modulate which of two response alternatives they are likely to choose. Recent efforts to uncover the mechanisms underlying this intriguing effect have revealed that free-choice priming can emerge even in the absence of automatized stimulus-response (S-R) associations between masked primes and specific motor responses, indicating that free choices can be influenced by a masked prime’s meaning (Ocampo, 2015). It remains unknown, however, whether masked primes bias response selections because they are implicitly classified according to task instructions, or because spreading activation occurs within the prime's semantic network. To adjudicate between these two possibilities, participants in the present experiment categorised targets as either animals or people and selected which of two response alternatives they wanted to make following presentation of a free-choice target. Crucially, while implicit classifications could proceed during processing of both animal and person masked primes, only animal primes could trigger spreading activation within their semantic network. This manipulation modulated free-choice priming; only masked animal primes influenced response selections to free-choice targets. This result indicates that an automatic spreading activation mechanism might underlie a masked prime’s ability to influence free-choice responses.