61 research outputs found
Running head: AGE OF ACQUISITION Age of Acquisition 1 Age of acquisition effects in reading aloud: Tests of cumulative frequency and frequency trajectory
No full textSeveral studies have reported that the age at which a word is learned affects skilled reading. This age of acquisition effect is potentially important for theories of reading and learning. The effect has been difficult to pin down, however, because the age at which a word is learned is correlated with many other lexical properties. Zevin and Seidenberg (2002) analyzed these phenomena using connectionist models that distinguished between cumulative frequency (the total number of times a word is experienced) and frequency trajectory (the distribution these experiences over time). The models prompted a reevaluation of the empirical literature on this topic. The present research tested and confirmed three behavioral predictions derived from these models. First, cumulative frequency has an impact on skilled word naming, more so than standard measures of frequency derived from norms such as Kucera and Francis (1967). Second, frequency trajectory affects age of acquisition: the timing of exposure to words affects how rapidly they are learned. However, frequency trajectory does not affect skilled reading aloud, because the consistencies in mapping between spelling and sound eventually wash out the effects of early differences in frequency of exposure. Thus, in skilled performance the timing of exposure to words is less important than the amount of exposure. The results clarify the conditions under which age-dependent learning effects occur in reading aloud. Age of acquisition effects in reading aloud: Tests of cumulative frequency and frequency trajectory The possibility that some aspects of language learning may be age dependent, in that they can only be fully mastered during a limited window of opportunity in early development, has been widely discussed (e.g., Doupe & Kuhl, 1..
Domain General Change Detection Accounts for“Dishabituation” Effects in Temporal–Parietal Regions in Functional Magnetic Resonance Imaging Studies of Speech Perception
No full textDomain General Change Detection Accounts for "Dishabituation" Effects in Temporal-Parietal Regions in Functional Magnetic Resonance Imaging Studies of Speech Perception
No full textFunctional magnetic resonance imaging ( fMRI) studies of speech sound categorization often compare conditions in which a stimulus is presented repeatedly to conditions in which multiple stimuli are presented. This approach has established that a set of superior temporal and inferior parietal regions respond more strongly to conditions containing stimulus change. Here, we examine whether this contrast is driven by habituation to a repeating condition or by selective responding to change. Experiment 1 directly tests this by comparing the observed response to long trains of stimuli against a constructed hemodynamic response modeling the hypothesis that no habituation occurs. The results are consistent with the view that enhanced response to conditions involving phonemic variability reflect change detection. In a second experiment, the specificity of these responses to linguistically relevant stimulus variability was studied by including a condition in which the talker, rather than phonemic category, was variable from stimulus to stimulus. In this context, strong change detection responses were observed to changes in talker, but not to changes in phoneme category. The results prompt a reconsideration of two assumptions common to fMRI studies of speech sound categorization: they suggest that temporoparietal responses in passive paradigms such as those used here are better characterized as reflecting change detection than habituation, and that their apparent selectivity to speech sound categories may reflect a more general preference for variability in highly salient or behaviorally relevant stimulus dimensions
Statistical learning of syllable sequences as trajectories through a perceptual similarity space
No full textLearning from sequential statistics is a general capacity common to many model systems. One form of statistical learning (SL) – learning to segment “words’ from continuous streams of speech syllables in which the only segmentation cue is ostensibly the transitional (or conditional) probability from one syllable to the next – has been studied in great detail. Typically, this phenomenon is modeled as the calculation of probabilities over discrete, featureless units. Here we present an alternative model, in which sequences are learned as trajectories through a similarity space. A simple recurrent network that coded syllables using representations capture the similarity relations among syllables correctly simulated the result of a classic SL study. We then used the simulations to identify a set of “words” that produces the reverse of the typical SL, i.e., part-words are predicted to be more familiar than words. Results from two experiments are consistent with simulation results
Native and non-native speech sound processing and the neural mismatch responses: A longitudinal study on classroom-based foreign language learning
No full textLearning a foreign language in a natural immersion context with high exposure to the new language has been shown to change the way speech sounds of that language are processed at the neural level. It remains unclear, however, to what extent this is also the case for classroom-based foreign language learning, particularly in children. To this end, we presented a mismatch negativity (MMN) experiment during EEG recordings as part of a longitudinal developmental study: 38 monolingual (Swiss-) German speaking children (7.5 years) were tested shortly before they started to learn English at school and followed up one year later. Moreover, 22 (Swiss-) German adults were recorded. Instead of the originally found positive mismatch response in children, an MMN emerged when applying a high-pass filter of 3 Hz. The overlap of a slow-wave positivity with the MMN indicates that two concurrent mismatch processes were elicited in children. The children's MMN in response to the non-native speech contrast was smaller compared to the native speech contrast irrespective of foreign language learning, suggesting that no additional neural resources were committed to processing the foreign language speech sound after one year of classroom-based learning
A sensitive period for shibboleths: The long tail and changing goals of speech perception over the course of development
No full textSpeech perception with temporally patterned noise maskers
No full textPatterned adverse listening conditions for word recognition task
Selective attention to phonology dynamically modulates initial encoding of auditory words within the left hemisphere
No full textSelective attention to phonology, i.e., the ability to attend to sub-syllabic units within spoken words, is a critical precursor to literacy acquisition. Recent functional magnetic resonance imaging evidence has demonstrated that a left-lateralized network of frontal, temporal, and posterior language regions, including the visual word form area, supports this skill. The current event-related potential (ERP) study investigated the temporal dynamics of selective attention to phonology during spoken word perception. We tested the hypothesis that selective attention to phonology dynamically modulates stimulus encoding by recruiting left-lateralized processes specifically while the information critical for performance is unfolding. Selective attention to phonology was captured by manipulating listening goals: skilled adult readers attended to either rhyme or melody within auditory stimulus pairs. Each pair superimposed rhyming and melodic information ensuring identical sensory stimulation. Selective attention to phonology produced distinct early and late topographic ERP effects during stimulus encoding. Data-driven source localization analyses revealed that selective attention to phonology led to significantly greater recruitment of left-lateralized posterior and extensive temporal regions, which was notably concurrent with the rhyme-relevant information within the word. Furthermore, selective attention effects were specific to auditory stimulus encoding and not observed in response to cues, arguing against the notion that they reflect sustained task setting. Collectively, these results demonstrate that selective attention to phonology dynamically engages a left-lateralized network during the critical time-period of perception for achieving phonological analysis goals. These findings suggest a key role for selective attention in on-line phonological computations. Furthermore, these findings motivate future research on the role that neural mechanisms of attention may play in phonological awareness impairments thought to underlie developmental reading disabilities
Dishabituation of the BOLD response to speech sounds
No full textAbstract Background Neural systems show habituation responses at multiple levels, including relatively abstract language categories. Dishabituation – responses to non-habituated stimuli – can provide a window into the structure of these categories, without requiring an overt task. Methods We used an event-related fMRI design with short interval habituation trials, in which trains of stimuli were presented passively during 1.5 second intervals of relative silence between clustered scans. Trains of four identical stimuli (standard trials) and trains of three identical stimuli followed by a stimulus from a different phonetic category (deviant trials) were presented. This paradigm allowed us to measure and compare the time course of overall responses to speech, and responses to phonetic change. Results Comparisons between responses to speech and silence revealed strong responses throughout the extent of superior temporal gyrus (STG) bilaterally. Comparisons between deviant and standard trials revealed dishabituation responses in a restricted region of left posterior STG, near the border with supramarginal gyrus (SMG). Novelty responses to deviant trials were also observed in right frontal regions and hippocampus. Conclusion A passive, dishabituation paradigm provides results similar to studies requiring overt responses. This paradigm can readily be extended for the study of pre-attentive processing of speech in populations such as children and second-language learners whose overt behavior is often difficult to interpret because of ancillary task demands.</p
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