Study Captures Brain’s Activity Processing Speech

from The University of Texas at Dallas News Center

Enter Dr. Michael Kilgard and Crystal Engineer. Kilgard is a neuroscientist in the School of Behavioral and Brain Sciences at the University of Texas at Dallas. His lab is one of the few in the world that studies how individual neurons process speech stimuli. Engineer is one of Professor Kilgard’s doctoral students. Together they conducted a study to provide the first-ever description of how speech sounds are processed by neurons in the brain. This insight may offer a new approach to treating children with speech processing disorders.

Conversation, speech acts, and memory

from Memory and Cognition

Speakers frequently have specific intentions that they want others to recognize (Grice, 1957). These specific intentions can be viewed as speech acts (Searle, 1969), and I argue that they play a role in long-term memory for conversation utterances. Five experiments were conducted to examine this idea. Participants in all experiments read scenarios ending with either a target utterance that performed a specific speech act (brag, beg, etc.) or a carefully matched control. Participants were more likely to falsely recall and recognize speech act verbs after having read the speech act version than after having read the control version, and the speech act verbs served as better recall cues for the speech act utterances than for the controls. Experiment 5 documented individual differences in the encoding of speech act verbs. The results suggest that people recognize and retain the actions that people perform with their utterances and that this is one of the organizing principles of conversation memory.

Distinctive encoding reduces the Jacoby-Whitehouse illusion

from Memory and Cognition

We investigated the influence of distinctive encoding on the Jacoby and Whitehouse (1989) illusion. Subjects studied visually presented words that were associated with either an auditory presentation of the same word (nondistinctive encoding) or a picture of the object (distinctive encoding). In both conditions, words were visually presented on the recognition test, and half were preceded by brief repetition primes. Priming test items increased hits and false alarms in the auditory condition, demonstrating the Jacoby-Whitehouse illusion. This illusion was reduced in the picture condition. In order to test whether this distinctiveness effect was caused by a recollection-based response strategy (i.e., the distinctiveness heuristic), we minimized recollection-based responding by having subjects make speeded recognition decisions. Contrary to the distinctiveness heuristic hypothesis, speeded responding did not eliminate the distinctiveness effect on the Jacoby-Whitehouse illusion. Picture encoding may reduce this illusion via a shift in preretrieval orientation, as opposed to a postretrieval editing process.

Processing modifier-head agreement in reading: evidence for a delayed effect of agreement

from Memory and Cognition

The present study examined whether type of inflectional case (semantic or grammatical) and phonological and morphological transparency affect the processing of Finnish modifier-head agreement in reading. Readers’ eye movement patterns were registered. In Experiment 1, an agreeing modifier condition (agreement was transparent) was compared with a no-modifier condition, and in Experiment 2, similar constructions with opaque agreement were used. In both experiments, agreement was found to affect the processing of the target noun with some delay. In Experiment 3, unmarked and case-marked modifiers were used. The results again demonstrated a delayed agreement effect, ruling out the possibility that the agreement effects observed in Experiments 1 and 2 reflect a mere modifier-presence effect. We concluded that agreement exerts its effect at the level of syntactic integration but not at the level of lexical access.

Repetition blindness in sentence contexts: not just an attribution?

from Memory and Cognition

Selective “blindness” to repeated words in rapid serial visual presentation (RSVP) occurs even when omitting these words compromises sentence syntax and meaning. The contributions of lexical and contextual factors to this repetition blindness (RB) phenomenon were evaluated using three tasks that combined RB and ambiguity resolution paradigms. During an RSVP sentence, a repeated word and matched but incongruous control were presented simultaneously, and participants were asked to report the entire sentence, including only the appropriate word. Substantial RB was evident in impaired report of repeated targets, whereas report of nonrepeated targets was enhanced when the distractor was a repeat. Experiment 2 confirmed these results with reduced reporting requirements, and Experiment 3 demonstrated the independence of repetition and sentence congruity effects. Results across all contexts support a lexical account of RB, which assumes that reactivation and identification of rapidly repeated words are impaired due to the refractory nature of lexical representations.

When you name the pizza you look at the coin and the bread: eye movements reveal semantic activation during word production

from Memory and Cognition

Two eyetracking experiments tested for activation of category coordinate and perceptually related concepts when speakers prepare the name of an object. Speakers saw four visual objects in a 2 x 2 array and identified and named a target picture on the basis of either category (e.g., “What is the name of the musical instrument?”) or visual-form (e.g., “What is the name of the circular object?”) instructions. There were more fixations on visual-form competitors and category coordinate competitors than on unrelated objects during name preparation, but the increased overt attention did not affect naming latencies. The data demonstrate that eye movements are a sensitive measure of the overlap between the conceptual (including visual-form) information that is accessed in preparation for word production and the conceptual knowledge associated with visual objects. Furthermore, these results suggest that semantic activation of competitor concepts does not necessarily affect lexical selection, contrary to the predictions of lexical-selection-by-competition accounts (e.g., Levelt, Roelofs, & Meyer, 1999).

Speech-Language Pathologists’ Assessment Practices for Children With Suspected Speech Sound Disorders: Results of a National Survey

from the American Journal of Speech-Language Pathology

Purpose: This study examined assessment procedures used by speech-language pathologists (SLPs) when assessing children suspected of having speech sound disorders (SSD). This national survey also determined the information participants obtained from clients’ speech samples, evaluation of non-native English speakers, and time spent on assessment.

Method: One thousand surveys were mailed to a randomly selected group of SLPs, self-identified as having worked with children with SSD. A total of 333 (33%) surveys were returned.

Results: The assessment tasks most frequently used included administering a commercial test, estimating intelligibility, assessing stimulability, and conducting a hearing screening. The amount of time dedicated to assessment activities (e.g., administering formal tests, contacting parents) varied across participants and was significantly related to years of experience but not caseload size. Most participants reported using informal assessment procedures, or English-only standardized tests, when evaluating non-native English speakers.

Conclusions: Most participants provided assessments that met federal guidelines to qualify children for special education services; however, additional assessment may be needed to create comprehensive treatment plans for their clients. These results provide a unique perspective on the assessment of children suspected of having SSD and should be helpful to SLPs as they examine their own assessment practices.

Reply to David Kemmerer’s “A critique of Mark D. Allen’s ‘The preservation of verb subcategory knowledge in a spoken language comprehension deficit’”

from Brain and Language

Allen [Allen, M. D. (2005). The preservation of verb subcategory knowledge in a spoken language comprehension deficit. Brain and Language, 95, 255–264] presents evidence from a single patient, WBN, to motivate a theory of lexical processing and representation in which syntactic information may be encoded and retrieved independently of semantic information. In his critique, Kemmerer argues that because Allen depended entirely on preposition-based verb subcategory violations to test WBN’s knowledge of correct argument structure, his results, at best, address a “strawman” theory. This argument rests on the assumption that preposition subcategory options are superficial syntactic phenomena which are not represented by argument structure proper. We demonstrate that preposition subcategory is in fact treated as semantically determined argument structure in the theories that Allen evaluated, and thus far from irrelevant. In further discussion of grammatically relevant versus irrelevant semantic features, Kemmerer offers a review of his own studies. However, due to an important design shortcoming in these experiments, we remain unconvinced. Reemphasizing the fact the Allen (2005) never claimed to rule out all semantic contributions to syntax, we propose an improvement in Kemmerer’s approach that might provide more satisfactory evidence on the distinction between the kinds of relevant versus irrelevant features his studies have addressed.

The influence of cochlear shape on low-frequency hearing

from the Proceedings of the National Academy of Sciences of the United States of America

The conventional theory about the snail shell shape of the mammalian cochlea is that it evolved essentially and perhaps solely to conserve space inside the skull. Recently, a theory proposed that the spiral’s graded curvature enhances the cochlea’s mechanical response to low frequencies. This article provides a multispecies analysis of cochlear shape to test this theory and demonstrates that the ratio of the radii of curvature from the outermost and innermost turns of the cochlear spiral is a significant cochlear feature that correlates strongly with low-frequency hearing limits. The ratio, which is a measure of curvature gradient, is a reflection of the ability of cochlear curvature to focus acoustic energy at the outer wall of the cochlear canal as the wave propagates toward the apex of the cochlea.

Dyslexia: a review of two theories

from Clinical and Experimental Optometry

Optometrists will frequently see patients, who may have a diagnosis or a suspected diagnosis of dyslexia (specific reading disorder) and will need to manage and counsel such patients. There are many propounded theories on the cause(s) of dyslexia. Although most professionals in this area consider that dyslexia is chiefly a linguistic disorder, the possibility of a visual component is contentious. This article is a selective review of two commonly discussed theories that suggest a visual component in dyslexia; the magnocellular deficit theory and Meares-Irlen syndrome.

Fully optimized discrimination of physiological responses to auditory stimuli

from theJournal of Neural Engineering

Abstract. The use of multivariate measurements to characterize brain activity (electrical, magnetic, optical) is widespread. The most common approaches to reduce the complexity of such observations include principal and independent component analyses (PCA and ICA), which are not well suited for discrimination tasks. We addressed two questions: first, how do the neurophysiological responses to elongated phonemes relate to tone and phoneme responses in normal children, and, second, how discriminable are these responses. We employed fully optimized linear discrimination analysis to maximally separate the multi-electrode responses to tones and phonemes, and classified the response to elongated phonemes. We find that discrimination between tones and phonemes is dependent upon responses from associative regions of the brain apparently distinct from the primary sensory cortices typically emphasized by PCA or ICA, and that the neuronal correlates corresponding to elongated phonemes are highly variable in normal children (about half respond with neural correlates of tones and half as phonemes). Our approach is made feasible by the increase in computational power of ordinary personal computers and has significant advantages for a wide range of neuronal imaging modalities.

Relationship between stuttering severity in children and their mothers speaking rate

from the Sao Paulo Medical Journal

CONTEXT AND OBJECTIVE: Stuttering is a complex disease that influences occupational, social, academic and emotional achievements. The aim of this study was to correlate the stuttering severity index with speaking rates of mothers and children. DESIGN AND SETTING: Cross-sectional study, at the child rehabilitation clinics of Tehran city. METHODS: 35 pairs of mothers and their children who stuttered were studied. There were 29 boys and six girls, of mean age 8.5 years (range: 5.1-12.0). Speech samples from the mother-child pairs were audiotaped for approximately 15 minutes, until a reciprocal verbal interaction had been obtained. This sample was then analyzed in accordance with a stuttering severity index test and speaking rate parameters. RESULTS: The research results outlined a significant relationship between the mothers speaking rate and their childrens stuttering severity. CONCLUSION: The results suggest that the mothers speaking rate should be incorporated in the assessment and treatment of stuttering.