Tristan J. Mahr

Bio: Tristan J. Mahr is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Intelligibility (communication) & Medicine. The author has an hindex of 6, co-authored 13 publications receiving 115 citations.

Using language input and lexical processing to predict vocabulary size.

Abstract: Children learn words by listening to caregivers, and the quantity and quality of early language input predict later language development. Recent research suggests that word recognition efficiency may influence the relationship between input and vocabulary growth. We asked whether language input and lexical processing at 28-39 months predicted vocabulary size one year later in 109 preschoolers. Input was measured using adult word counts from LENA recordings. We used the visual world paradigm and measured lexical processing as the rate of change in proportion of looks to target. Regression analysis showed that lexical processing did not constrain the effect of input on vocabulary size. We also found that input and processing were more reliable predictors of receptive than expressive vocabulary growth.

Comparing Automatic Eye Tracking and Manual Gaze Coding Methods in Young Children with Autism Spectrum Disorder.

Abstract: Eye-gaze methods offer numerous advantages for studying cognitive processes in children with autism spectrum disorder (ASD), but data loss may threaten the validity and generalizability of results. Some eye-gaze systems may be more vulnerable to data loss than others, but to our knowledge, this issue has not been empirically investigated. In the current study, we asked whether automatic eye-tracking and manual gaze coding produce different rates of data loss or different results in a group of 51 toddlers with ASD. Data from both systems were gathered (from the same children) simultaneously, during the same experimental sessions. As predicted, manual gaze coding produced significantly less data loss than automatic eye tracking, as indicated by the number of usable trials and the proportion of looks to the images per trial. In addition, automatic eye-tracking and manual gaze coding produced different patterns of results, suggesting that the eye-gaze system used to address a particular research question could alter a study's findings and the scientific conclusions that follow. It is our hope that the information from this and future methodological studies will help researchers to select the eye-gaze measurement system that best fits their research questions and target population, as well as help consumers of autism research to interpret the findings from studies that utilize eye-gaze methods with children with ASD. Autism Res 2020, 13: 271-283. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: The current study found that automatic eye-tracking and manual gaze coding produced different rates of data loss and different overall patterns of results in young children with ASD. These findings show that the choice of eye-gaze system may impact the findings of a study-important information for both researchers and consumers of autism research.

Vocabulary Size and Auditory Word Recognition in Preschool Children

Abstract: Recognizing familiar words quickly and accurately facilitates learning new words, as well as other aspects of language acquisition. This study used the visual world paradigm with semantic and phonological competitors to study lexical processing efficiency in 2- to 5-year-old children. Experiment 1 found this paradigm was sensitive to vocabulary-size differences. Experiment 2 included a more diverse group of children who were tested in their native dialect (either African American English or mainstream American English). No effect of stimulus dialect was observed. The results showed that vocabulary size was a better predictor of eye gaze patterns than was maternal education, but that maternal education level had a moderating effect; as maternal education level increased, vocabulary size was less predictive of lexical processing efficiency.

Longitudinal Growth in Single-Word Intelligibility Among Children With Cerebral Palsy From 24 to 96 Months of Age: Effects of Speech-Language Profile Group Membership on Outcomes

Abstract: Purpose We examined whether there were differences among speech-language profile groups of children with cerebral palsy (CP) in age of crossing 25%, 50%, and 75% intelligibility thresholds; age of greatest intelligibility growth; rate of intelligibility growth; maximum attained intelligibility at 8 years; and how well intelligibility at 36 months predicts intelligibility at 96 months when group membership is accounted for. Profile groups were children with no speech motor impairment (NSMI), those with speech motor impairment and language comprehension that is typically developing (SMI-LCT), and those with speech motor impairment and language comprehension impairment (SMI-LCI). Method Sixty-eight children with CP were followed longitudinally between 24 and 96 months of age. A total of 564 time points were examined across children (M = 8.3 time points per child, SD = 2.6). We fitted a nonlinear random effects model for longitudinal observations, allowing for differences between profile groups. We used the fitted model trajectories to generate descriptive analyses of intelligibility growth by group and to generate simulations to analyze how well 36-month intelligibility data predicted 96-month data accounting for profile groups. Results Children with CP who have NSMI have different growth and better intelligibility outcomes than those with speech motor impairment. Children with SMI-LCT tend to have better outcomes but similar intelligibility growth as children with SMI-LCI. There may be a subset of children that cut across SMI-LCI and SMI-LCT groups who have severe speech motor involvement and show limited growth in intelligibility. Conclusions Intelligibility outcomes for children with CP are affected by profile group membership. Intelligibility growth tends to be delayed in children with speech motor impairment. Intelligibility at 3 years is highly predictive of later outcomes regardless of profile group. Intervention decision making should include consideration of early intelligibility, and treatment directions should include consideration of augmentative and alternative communication.

Predicting while comprehending language: a theory and review

Abstract: Researchers agree that comprehenders regularly predict upcoming language, but they do not always agree on what prediction is (and how to differentiate it from integration) or what constitutes evidence for it. After defining prediction, we show that it occurs at all linguistic levels from semantics to form, and then propose a theory of which mechanisms comprehenders use to predict. We argue that they most effectively predict using their production system (i.e., prediction-by-production): They covertly imitate the linguistic form of the speaker’s utterance and construct a representation of the underlying communicative intention. Comprehenders can then run this intention through their own production system to prepare the predicted utterance. But doing so takes time and resources, and comprehenders vary in the extent of preparation, with many groups of comprehenders (non-native speakers, illiterates, children, and older adults) using it less than typical native young adults. We thus argue that prediction-by-production is an optional mechanism, which is augmented by mechanisms based on association. Support for our proposal comes from many areas of research (electrophysiological, eye-tracking, and behavioral studies of reading, spoken language processing in the context of visual environments, speech processing, and dialogue).

Rapid Release From Listening Effort Resulting From Semantic Context, and Effects of Spectral Degradation and Cochlear Implants.

Abstract: People with hearing impairment are thought to rely heavily on context to compensate for reduced audibility. Here, we explore the resulting cost of this compensatory behavior, in terms of effort and the efficiency of ongoing predictive language processing. The listening task featured predictable or unpredictable sentences, and participants included people with cochlear implants as well as people with normal hearing who heard full-spectrum/unprocessed or vocoded speech. The crucial metric was the growth of the pupillary response and the reduction of this response for predictable versus unpredictable sentences, which would suggest reduced cognitive load resulting from predictive processing. Semantic context led to rapid reduction of listening effort for people with normal hearing; the reductions were observed well before the offset of the stimuli. Effort reduction was slightly delayed for people with cochlear implants and considerably more delayed for normal-hearing listeners exposed to spectrally degraded noise-vocoded signals; this pattern of results was maintained even when intelligibility was perfect. Results suggest that speed of sentence processing can still be disrupted, and exertion of effort can be elevated, even when intelligibility remains high. We discuss implications for experimental and clinical assessment of speech recognition, in which good performance can arise because of cognitive processes that occur after a stimulus, during a period of silence. Because silent gaps are not common in continuous flowing speech, the cognitive/linguistic restorative processes observed after sentences in such studies might not be available to listeners in everyday conversations, meaning that speech recognition in conventional tests might overestimate sentence-processing capability.

Behavioural methods for investigating morphological and syntactic processing in children. Developmental psycholinguistics: On-line methods in children's language processing.

Abstract: While most first language acquisition research to date has focused on the development of children's linguistic competence, a number of research teams have also investigated the mechanisms children employ to process sentence-level and word-level information in real time, by applying experimental techniques familiar from the adult processing literature to children. This chapter presents an overview of different kinds of behavioral tasks for investigating both morphological and syntactic processing in children focusing on three techniques that we have explored in our own research on children's on-line language processing: self-paced listening, cross-modal priming, and speeded production.