Speech unfolds over time and the cues for even a single phoneme are rarely available simultaneously. Consequently, to recognize a single phoneme listeners must integrate material over several hundred milliseconds. Prior work contrasts two accounts: 1) a memory buffer account in which listeners accumulate auditory information in memory and only access higher level representations (i.e., lexical representations) when sufficient information has arrived; and 2) an immediate integration scheme in which lexical representations can be partially activated on the basis of early cues and then updated when more information arises. These studies have uniformly shown evidence for immediate integration for a variety of phonetic distinctions. We attempted to extend this to fricatives, a class of speech sounds which requires not only temporal integration of asynchronous cues (the frication, followed by the formant transitions 150–350 msec later), but also integration across different frequency bands, and compensation for contextual factors like coarticulation. Eye-movements in the visual world paradigm and showed clear evidence for a memory buffer. Results were replicated in five experiments, ruling out methodological factors and tying the release of the buffer to the onset of the vowel. These findings support a general auditory account for speech by suggesting that the acoustic nature of particular speech sounds may have large effects on how they are processed. It also has major implications for theories of auditory and speech perception by raising the possibility of a encapsulated memory buffers in early auditory processing.

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Speech unfolds over time and the cues for even a single phoneme are rarely available simultaneously. Consequently, to recognize a single phoneme listeners must integrate material over several hundred milliseconds. Prior work contrasts two accounts: 1) a memory buffer account in which listeners accumulate auditory information in memory and only access higher level representations (i.e. lexical representations) when sufficient information has arrived; and 2) an immediate integration strategy in which lexical representations can be partially activated on the basis of early cues and then updated when more information arises. These studies have uniformly shown evidence for immediate integration for a variety of phonetic distinctions. We attempted to extend this to fricatives, a class of speech sounds which requires not only temporal integration of asynchronous cues (the frication, followed by the formant transitions 150-350 msec later), but also integration across different frequency bands, and compensation for contextual factors like coarticulation. Experiments employed eye-movements in the visual world paradigm and showed clear evidence for a memory buffer. Results were replicated in five experiments, ruling out methodological factors and tying the release of the buffer to the onset of the vowel. These findings support a general auditory account for speech by suggesting that the acoustic nature of particular speech sounds may have large effects on how they are processed. It also has major implications for theories of auditory and speech perception by raising the possibility of an encapsulated memory buffer in early auditory processing.

Eight to 11% of children have a clinical disorder in oral language (Developmental Language Disorder, DLD), with pervasive deficits in all levels of language that persist through adulthood. Word-level processing may be critical as words link phonology, orthography, syntax and semantics. Thus, a lexical deficit could cascade throughout language. Cognitively, word recognition is a competition process: as the input (e.g., lizard) unfolds, multiple candidates (liver, wizard) compete for recognition. Children with DLD do not fully resolve this competition, but it is unclear what cognitive mechanisms underlie this. We examined lexical inhibition, the ability of more active words to suppress competitors in 79 adolescents with and without DLD.Participants heard words (e.g. net) in which the onset was manipulated to briefly favor a competitor (neck). This was predicted to inhibit the target, slowing recognition. Word recognition was measured using a task in which participants heard the stimulus, and clicked on a picture of the item from an array of competitors, while eye-movement were monitored as a measure of how strongly the participant was committed to that interpretation over time. TD listeners showed evidence of inhibition with greater interference for stimuli that briefly activated a competitor word. DLD listeners did not. This suggests deficits in DLD may stem from a failure to engage lexical inhibition. This in turn could have ripple effects throughout the language system. This supports theoretical approaches to DLD that emphasize lexical-level deficits; and deficits in real-time processing.