Sensory auditory interval perception errors in developmental dyslexia

Perceptual learning as a possible new approach for remediation and prevention of developmental dyslexia

Event Abstract Back to Event The distraction paradigm: Equating difficulty is difficult. Karlye Damaso1*, Alexander L. Provost1, Pat Michie1, Scott Brown1, Ulrich Schall1 and Juanita Todd1 1 University of Newcastle, Australia The distraction paradigm (Schröger, 1996, 1997) provides an empirical test of how the elicitation of mismatch negativity (MMN) impacts upon the attentional resources available to perform a behavioural task. In these paradigms a task-irrelevant sound sequence that contains MMN eliciting characteristics is superimposed on a behavioural task that occupies the focus of attention. The subsequent impact MMN has on attentional resources results in robust behavioural effects – increased reaction times and error rates. These behavioural effects can be muted by increasing task difficulty. That is, under increased task difficulty, increases in RT and error rates that typically follow MMN do not occur (Berti et al., 2004; Berti & Schröger, 2003). Broader cognitive literature suggests that the level of difficulty experienced in a given task can differ within and between individuals (Lavie, 2005). These differences can impact on task performance at an individual and group level (Lavie, 2005), introducing noise and clouding effects. To address this, tasks can be designed with inbuilt algorithms that equate difficulty within and between participants. To date, distraction paradigm research has not utilised difficulty-calibrated tasks. We aimed to create a distraction paradigm task with an inbuilt calibration feature that would equate task difficulty within and between participants. We used a novel auditory-visual distraction paradigm task with the task irrelevant sound sequence consisting of a duration deviant MMN sequence, and a visual inspection time behavioural task. Visual inspection time duration was varied within and between participants so that task difficulty would be calibrated at ~85% accuracy. Despite the elicitation of a distinct MMN, no behavioural effects were observed – increases in RT and error rates that typically follow MMN did not occur. We discuss reasons why our attempt to create a task with an inbuilt calibration feature may have been unsuccessful in this variation of an auditory-visual distraction paradigm task. Acknowledgements We gratefully acknowledge Mr. Gavin Cooper for his assistance in task design and programming. Keywords: mismatch negativity (MMN), distraction paradigm, distraction, Attention, task difficulty Conference: ASP2015 - 25th Annual Conference of the Australasian Society for Psychophysiology, Sydney, Australia, 2 Dec - 4 Dec, 2015. Presentation Type: Poster Presentation Topic: Psychophysiology Citation: Damaso K, Provost AL, Michie P, Brown S, Schall U and Todd J (2015). The distraction paradigm: Equating difficulty is difficult.. Conference Abstract: ASP2015 - 25th Annual Conference of the Australasian Society for Psychophysiology. doi: 10.3389/conf.fnhum.2015.219.00014 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Oct 2015; Published Online: 30 Nov 2015. * Correspondence: Ms. Karlye Damaso, University of Newcastle, Newcastle, Australia, Karlye.Damaso@uon.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Karlye Damaso Alexander L Provost Pat Michie Scott Brown Ulrich Schall Juanita Todd Google Karlye Damaso Alexander L Provost Pat Michie Scott Brown Ulrich Schall Juanita Todd Google Scholar Karlye Damaso Alexander L Provost Pat Michie Scott Brown Ulrich Schall Juanita Todd PubMed Karlye Damaso Alexander L Provost Pat Michie Scott Brown Ulrich Schall Juanita Todd Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

It has been suggested that auditory and visual sequential processing deficits contribute to phonological disorders in developmental dyslexia. As an alternative explanation to a phonological deficit as the proximal cause for reading disorders, the visual attention span hypothesis (VA Span) suggests that difficulties in processing visual elements simultaneously lead to dyslexia, regardless of the presence of a phonological disorder. In this study, we assessed whether deficits in processing simultaneously displayed visual or auditory elements is linked to dyslexia associated with a VA Span impairment. Sixteen children with developmental dyslexia and 16 age-matched skilled readers were assessed on visual and auditory search tasks. Participants were asked to detect a target presented simultaneously with 3, 9, or 15 distracters. In the visual modality, target detection was slower in the dyslexic children than in the control group on a “serial” search condition only: the intercepts (but not the slopes) of the search functions were higher in the dyslexic group than in the control group. In the auditory modality, although no group difference was observed, search performance was influenced by the number of distracters in the control group only. Within the dyslexic group, not only poor visual search (high reaction times and intercepts) but also low auditory search performance (d′) strongly correlated with poor irregular word reading accuracy. Moreover, both visual and auditory search performance was associated with the VA Span abilities of dyslexic participants but not with their phonological skills. The present data suggests that some visual mechanisms engaged in “serial” search contribute to reading and orthographic knowledge via VA Span skills regardless of phonological skills. The present results further open the question of the role of auditory simultaneous processing in reading as well as its link with VA Span skills.

Atypical visual selective attention in children with dyslexia: evidence from N2pc and PD.

Reading is vital to every aspect of modern life, exacerbated by reliance of the internet, email, and social media on the written medium. Developmental dyslexia (DD) characterizes a disorder in which the core deficit involves reading. Traditionally, DD is thought to be associated with a phonological impairment. However, recent evidence has begun to suggest that the reading impairment in some individuals is provoked by a visual processing deficit. In this paper, we present WISC‐IV data from more than 300 Italian children with a diagnosis of DD to investigate the manifestation of phonological and visual subtypes. Our results indicate the existence of two clusters of children with DD. In one cluster, the deficit was more pronounced in the phonological component, while both clusters were impaired in visual processing. These data indicate that DD may be an umbrella term that encompasses different profiles. From a theoretical perspective, our results demonstrate that dyslexia cannot be explained in terms of an isolated phonological deficit alone; visual impairment plays a crucial role. Moreover, general rather than specific accounts of DD are discussed.

The simultaneous auditory processing skills of 17 dyslexic children and 17 skilled readers were measured using a dichotic listening task. Results showed that the dyslexic children exhibited difficulties reporting syllabic material when presented simultaneously. As a measure of simultaneous visual processing, visual attention span skills were assessed in the dyslexic children. We presented the dyslexic children with a phonological short-term memory task and a phonemic awareness task to quantify their phonological skills. Visual attention spans correlated positively with individual scores obtained on the dichotic listening task while phonological skills did not correlate with either dichotic scores or visual attention span measures. Moreover, all the dyslexic children with a dichotic listening deficit showed a simultaneous visual processing deficit, and a substantial number of dyslexic children exhibited phonological processing deficits whether or not they exhibited low dichotic listening scores. These findings suggest that processing simultaneous auditory stimuli may be impaired in dyslexic children regardless of phonological processing difficulties and be linked to similar problems in the visual modality.

Cerebellar symmetry in dyslexics

The extent to which impaired visual and phonological mechanisms may contribute to the manifestation of developmental dyslexia across orthographies of varying depth has yet to be fully established. By adopting a cross-linguistic approach, the current study aimed to explore the nature of visual and phonological processing in developmental dyslexic readers of shallow (Italian) and deep (English) orthographies, and specifically the characterisation of visual processing deficits in relation to orthographic depth. To achieve this aim, we administered a battery of non-reading visual and phonological tasks. Developmental dyslexics performed worse than typically developing readers on all visual and phonological tasks. Critically, readers of the shallow orthography were disproportionately impaired on visual processing tasks. Our results suggest that the impaired reading and associated deficits observed in developmental dyslexia are anchored by dual impairments to visual and phonological mechanisms that underpin reading, with the magnitude of the visual deficit varying according to orthographic depth.

The nature and cause of auditory processing deficits in dyslexic individuals have been debated for decades. Auditory processing deficits were argued to be the first step in a causal chain of difficulties, leading to difficulties in speech perception and thereby phonological processing and literacy difficulties. More recently, it has been argued that auditory processing difficulties may not be causally related to language and literacy difficulties. This study compares two groups who have phonological processing impairments for different reasons: dyslexia and a history of otitis media (OM). We compared their discrimination thresholds and response variability to chronological age- and reading age-matched controls, across three auditory processing tasks: frequency discrimination, rise-time discrimination and speech perception. Dyslexic children showed raised frequency discrimination thresholds in comparison with age-matched controls but did not differ from reading age-matched controls or individuals with a history of OM. There were no group differences on speech perception or rise-time tasks. For the dyslexic children, there was an association between phonological awareness and frequency discrimination response variability, but no association with thresholds. These findings are not consistent with a 'causal chain' explanation but could be accounted for within a multiple deficits view of literacy difficulties.

Current theories on dyslexia refer either to phonological or perceptual factors. The phonological theory explains dyslexia by a deficit in phonological awareness which would affect the build-up of grapheme–phoneme correspondences. This is challenged by the magnocellular theory which ascribes dyslexia to a deficit in temporal processing of auditory and visual signals. However, the auditory deficit in dyslexia is not specifically temporal. Further, the perceptual deficit is not merely sensory but cognitive in nature as evidenced by both weaker discrimination of phonological contrasts and stronger discrimination of differences within phonological categories. This reflects a deficit in “Categorical Perception” which is also sometimes associated with a weaker precision of the perceptual boundary between phonemes (“Boundary Precision” deficit). Categorical deficits are more reliable than magnocellular ones and might be no less reliable than those in phonemic awareness. The categorical deficit suggests that dyslexic children perceive speech with allophonic rather than phonemic units, which has straightforward consequences for the acquisition of phoneme–grapheme correspondences and might also explain the other phonological troubles associated with dyslexia.

A mismatch negativity event-related potential protocol was administered to dyslexic children and their respective controls to test whether a specific auditory deficit concerning phonetic processing or a lower level auditory processing deficit was present in developmental dyslexia. Three different contrast conditions were explored, including nonphonological sounds, contrasted in pitch and duration, and phonemes. Mismatch negativity amplitudes differed significantly between groups in the duration condition, whereas no differences were found in the frequency and phoneme conditions. Moreover, the dyslexic children had delayed mismatch negativity latencies in the three contrast conditions. Our results suggest a deficit in low-level auditory discrimination in dyslexic children, in particular when detecting stimulus duration, and support the rapid auditory processing theory of dyslexia.

Brain plasticity in developmental dyslexia after phonological treatment: A beta EEG band study

Developmental dyslexia is often characterized by a dual deficit in both word recognition accuracy and general processing speed. While previous research into dyslexic word recognition may have suffered from speed-accuracy trade-off, the present study employed a novel eye-tracking task that is less prone to such confounds. Participants (10 dyslexics and 12 controls) were asked to look at real word stimuli, and to ignore simultaneously presented non-word stimuli, while their eye-movements were recorded. Improvements in word recognition accuracy over time were modeled in terms of a continuous non-linear function. The words' rhyme consistency and the non-words' lexicality (unpronounceable, pronounceable, pseudohomophone) were manipulated within-subjects. Speed-related measures derived from the model fits confirmed generally slower processing in dyslexics, and showed a rhyme consistency effect in both dyslexics and controls. In terms of overall error rate, dyslexics (but not controls) performed less accurately on rhyme-inconsistent words, suggesting a representational deficit for such words in dyslexics. Interestingly, neither group showed a pseudohomophone effect in speed or accuracy, which might call the task-independent pervasiveness of this effect into question. The present results illustrate the importance of distinguishing between speed- vs. accuracy-related effects for our understanding of dyslexic word recognition.

Language impairments can have a devastating effect on the individual’s life. Brain damage such as stroke may cause varying degrees of impaired language. Even milder language problems, such as developmental dyslexia or specific language impairment, can have long-lasting detrimental effects on the individual’s life, affecting both success at school as well as motivation and even self-esteem. In recent years, the mismatch negativity (MMN) has been intensively applied to study the neural basis of language impairments. These studies have shown that the MMN, which reflects the early stages of cortical sound discrimination, is abnormal in a large variety of language impairments. Furthermore, a close relationship between the MMN and some language disorders is suggested by significant correlations between the MMN and language test results. Further support is provided by follow-up studies suggesting that the MMN parameters may predict future language problems in children and by investigations indicating that intervention programs with an ameliorating effect also concurrently change the MMN. However, when interpreting the implications of MMN results it is important to acknowledge that this response specifically reflects early stages of auditory discrimination and should, therefore, be combined with measures probing the further steps of auditory processing for a more complete picture of the underlying deficits of language. The current review addresses how the MMN can be used in determining auditory impairments in language disorders such as aphasia, dyslexia, autism spectrum, and specific language impairment.

Cortical basis for dichotic pitch perception in developmental dyslexia