A General Audiovisual Temporal Processing Deficit in Adult Readers With Dyslexia

When 2 become 1: Autistic simultaneity judgements about asynchronous audiovisual speech

It has been proposed that autistic people experience a temporal distortion whereby the temporal binding window of multisensory integration is extended. Research to date has focused on autistic children so whether these differences persist into adulthood remains unknown. In addition, the possibility that the previous observations have arisen from between-group differences in response bias, rather than perceptual differences, has not been addressed. Participants completed simultaneity judgements of audiovisual speech stimuli across a range of stimulus-onset asynchronies. Response times and accuracy data were fitted to a drift-diffusion model so that the drift rate (a measure of processing efficiency) and starting point (response bias) could be estimated. In Experiment 1, we tested a sample of non-autistic adults who completed the Autism Quotient questionnaire. Autism Quotient score was not correlated with either drift rate or response bias, nor were there between-group differences when splitting based on the first and third quantiles of scores. In Experiment 2, we compared the performance of autistic with a group of non-autistic adults. There were no between-group differences in either drift rate or starting point. The results of this study do not support the previous suggestion that autistic people have an extended temporal binding window for audiovisual speech. In addition, exploratory analysis revealed that operationalising the temporal binding window in different ways influenced whether a group difference was observed, which is an important consideration for future work.

Synchrony perception across senses: A systematic review of temporal binding window changes from infancy to adolescence in typical and atypical development

Sensory integration is increasingly acknowledged as being crucial for the development of cognitive and social abilities. However, its developmental trajectory is still little understood. This systematic review delves into the topic by investigating the literature about the developmental changes from infancy through adolescence of the Temporal Binding Window (TBW) - the epoch of time within which sensory inputs are perceived as simultaneous and therefore integrated. Following comprehensive searches across PubMed, Elsevier, and PsycInfo databases, only experimental, behavioral, English-language, peer-reviewed studies on multisensory temporal processing in 0-17-year-olds have been included. Non-behavioral, non-multisensory, and non-human studies have been excluded as those that did not directly focus on the TBW. The selection process was independently performed by two Authors. The 39 selected studies involved 2859 participants in total. Findings indicate a predisposition towards cross-modal asynchrony sensitivity and a composite, still unclear, developmental trajectory, with atypical development associated to increased asynchrony tolerance. These results highlight the need for consistent and thorough research into TBW development to inform potential interventions.

Multisensory integration in the mammalian brain: diversity and flexibility in health and disease

Multisensory integration (MSI) occurs in a variety of brain areas, spanning cortical and subcortical regions. In traditional studies on sensory processing, the sensory cortices have been considered for processing sensory information in a modality-specific manner. The sensory cortices, however, send the information to other cortical and subcortical areas, including the higher association cortices and the other sensory cortices, where the multiple modality inputs converge and integrate to generate a meaningful percept. This integration process is neither simple nor fixed because these brain areas interact with each other via complicated circuits, which can be modulated by numerous internal and external conditions. As a result, dynamic MSI makes multisensory decisions flexible and adaptive in behaving animals. Impairments in MSI occur in many psychiatric disorders, which may result in an altered perception of the multisensory stimuli and an abnormal reaction to them. This review discusses the diversity and flexibility of MSI in mammals, including humans, primates and rodents, as well as the brain areas involved. It further explains how such flexibility influences perceptual experiences in behaving animals in both health and disease. This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Audiovisual multisensory integration in individuals with reading and language impairments: A systematic review and meta-analysis

Differences in sensory function have been documented for a number of neurodevelopmental conditions, including reading and language impairments. Prior studies have measured audiovisual multisensory integration (i.e., the ability to combine inputs from the auditory and visual modalities) in these populations. The present study sought to systematically review and quantitatively synthesize the extant literature on audiovisual multisensory integration in individuals with reading and language impairments. A comprehensive search strategy yielded 56 reports, of which 38 were used to extract 109 group difference and 68 correlational effect sizes. There was an overall difference between individuals with reading and language impairments and comparisons on audiovisual integration. There was a nonsignificant trend towards moderation according to sample type (i.e., reading versus language) and publication/small study bias for this model. Overall, there was a small but non-significant correlation between metrics of audiovisual integration and reading or language ability; this model was not moderated by sample or study characteristics, nor was there evidence of publication/small study bias. Limitations and future directions for primary and meta-analytic research are discussed.

Reduced audiovisual temporal sensitivity in Chinese children with dyslexia

Background

Temporal processing deficits regarding audiovisual cross-modal stimuli could affect children's speed and accuracy of decoding.

Aim

To investigate the characteristics of audiovisual temporal sensitivity (ATS) in Chinese children, with and without developmental dyslexia and its impact on reading ability.

Methods

The audiovisual simultaneity judgment and temporal order judgment tasks were performed to investigate the ATS of 106 Chinese children (53 with dyslexia) aged 8 to 12 and 37 adults without a history of dyslexia. The predictive effect of children's audiovisual time binding window on their reading ability and the effects of extra cognitive processing in the temporal order judgment task on participants' ATS were also investigated.

Outcomes and results

With increasing inter-stimulus intervals, the percentage of synchronous responses in adults declined more rapidly than in children. Adults and typically developing children had significantly narrower time binding windows than children with dyslexia. The size of visual stimuli preceding auditory stimuli time binding window had a marginally significant predictive effect on children's reading fluency. Compared with the simultaneity judgment task, the extra cognitive processing of the temporal order judgment task affected children's ATS.

Conclusion and implications

The ATS of 8-12-year-old Chinese children is immature. Chinese children with dyslexia have lower ATS than their peers.

The influence of temporal asynchrony on character-speech integration in Chinese children with and without dyslexia: An ERP study

Dyslexic readers have been reported to show abnormal temporal acuity and multisensory integration deficiency. Here, we investigated the influence of temporal intervals on Chinese character-speech integration in children with and without dyslexia. Visual characters were presented synchronously to the onset of speech sounds (AV0) or before speech sound by 300 ms (AV300). Event-related potentials (ERP) evoked by congruent condition (speech sounds presented with congruent Chinese characters) and by baseline condition (speech sounds presented with Korean characters) were compared. Typically developing (TD) children exhibited congruency effect in AV0 condition, whereas dyslexic children exhibited congruency effect in AV300 condition. Moreover, congruency effect in TD children was due to enhanced neural activation to congruent trials, congruency effect in dyslexic children was contributed by neural suppression for baseline trials. These results suggested that different underlying mechanisms were involved in character-speech integration for typical and dyslexic children.

Brain Source Correlates of Speech Perception and Reading Processes in Children With and Without Reading Difficulties

Neural correlates in reading and speech processing have been addressed extensively in the literature. While reading skills and speech perception have been shown to be associated with each other, their relationship remains debatable. In this study, we investigated reading skills, speech perception, reading, and their correlates with brain source activity in auditory and visual modalities. We used high-density event-related potentials (ERPs), fixation-related potentials (FRPs), and the source reconstruction method. The analysis was conducted on 12–13-year-old schoolchildren who had different reading levels. Brain ERP source indices were computed from frequently repeated Finnish speech stimuli presented in an auditory oddball paradigm. Brain FRP source indices were also computed for words within sentences presented in a reading task. The results showed significant correlations between speech ERP sources and reading scores at the P100 (P1) time range in the left hemisphere and the N250 time range in both hemispheres, and a weaker correlation for visual word processing N170 FRP source(s) in the posterior occipital areas, in the vicinity of the visual word form areas (VWFA). Furthermore, significant brain-to-brain correlations were found between the two modalities, where the speech brain sources of the P1 and N250 responses correlated with the reading N170 response. The results suggest that speech processes are linked to reading fluency and that brain activations to speech are linked to visual brain processes of reading. These results indicate that a relationship between language and reading systems is present even after several years of exposure to print.

Individual differences in beta frequency correlate with the audio-visual fusion illusion

Presenting one flash with two beeps induces a perception of two flashes (audio-visual [AV] fission illusion), while presenting two flashes with one beep induces a perception of one flash (fusion illusion). Although previous studies showed a relationship between the frequency of the alpha rhythm (alpha cycle) and one's susceptibility to the fission illusion, the relationship between neural oscillations and the fusion illusion is unknown. Using electroencephalography, here I investigated the frequency of oscillatory signals in the pre-stimulus period and found a significant correlation between the beta rhythm and the fusion illusion; specifically, participants with a lower beta frequency showed a larger fusion illusion. These data indicate two separate time windows of AV integration in the human brain, one defined by the alpha cycle (fission) and another defined by the beta cycle (fusion).

Facial speech processing in children with and without dyslexia

What role does the presence of facial speech play for children with dyslexia? Current literature proposes two distinctive claims. One claim states that children with dyslexia make less use of visual information from the mouth during speech processing due to a deficit in recruitment of audiovisual areas. An opposing claim suggests that children with dyslexia are in fact reliant on such information in order to compensate for auditory/phonological impairments. The current paper aims at directly testing these contrasting hypotheses (here referred to as "mouth insensitivity" versus "mouth reliance") in school-age children with and without dyslexia, matched on age and listening comprehension. Using eye tracking, in Study 1, we examined how children look at the mouth across conditions varying in speech processing demands. The results did not indicate significant group differences in looking at the mouth. However, correlation analyses suggest potentially important distinctions within the dyslexia group: those children with dyslexia who are better readers attended more to the mouth while presented with a person's face in a phonologically demanding condition. In Study 2, we examined whether the presence of facial speech cues is functionally beneficial when a child is encoding written words. The results indicated lack of overall group differences on the task, although those with less severe reading problems in the dyslexia group were more accurate when reading words that were presented with articulatory facial speech cues. Collectively, our results suggest that children with dyslexia differ in their "mouth reliance" versus "mouth insensitivity," a profile that seems to be related to the severity of their reading problems.

Post-Attentive Integration and Topographic Map Distribution During Audiovisual Processing in Dyslexia: A P300 Event-Related Component Analysis

Background

Research on audiovisual post-attentive integration has been carried out using a variety of experimental paradigms and experimental groups but not yet studied in dyslexia. We investigated post-attentive integration and topographic voltage distribution in children with dyslexia by analysing the P300 event-related potential (ERP) component.

Methods

We used a 128-child ERP net for the ERP experiment. Two types of stimuli were presented as either congruent or incongruent stimuli. Congruent stimuli included a matching auditory sound with an animal image, whereas incongruent stimuli included unmatched animal sounds. A total of 24 age-matched children were recruited in the control (n = 12) and dyslexia (n = 12) groups. Children pressed button ‘1’ or ‘2’ when presented with congruent or incongruent stimuli, respectively. The P300 amplitudes and latencies with topographic voltage distribution were analysed for both groups.

Results

The dyslexia group evoked significantly higher P300 amplitudes at the T4 area than the control group. No significant differences were found in cases of P300 latency. Moreover, the dyslexia group demonstrated a higher intensity of P300 voltage distribution in the right parietal and left occipital areas than the control group.

Conclusion

Post-attentive integration for children with dyslexia is higher and that this integration process implicated the parietal and occipital areas.

Unisensory and multisensory temporal processing in autism and dyslexia: A systematic review and meta-analysis

This study presents a comprehensive systematic review and meta-analysis of temporal processing in autism spectrum disorder (ASD) and developmental dyslexia (DD), two neurodevelopmental disorders in which temporal processing deficits have been highly researched. The results provide strong evidence for impairments in temporal processing in both ASD (g = 0.48) and DD (g = 0.82), as measured by judgments of temporal order and simultaneity. In individual analyses, multisensory temporal processing was impaired for both ASD and DD, and unisensory auditory, visual and tactile processing were all impaired in DD. In ASD, speech stimuli showed moderate impairment effect sizes, whereas nonspeech stimuli showed small effects. Greater reading and spelling skills in DD were associated with greater temporal precision. Temporal deficits did not show changes with age in either disorder. In addition to more clearly defining temporal impairments in ASD and DD, the results highlight common and distinct patterns of temporal processing between these disorders. Deficits are discussed in relation to existing theoretical models, and recommendations are made for future research.

Audiovisual temporal integration: Cognitive processing, neural mechanisms, developmental trajectory and potential interventions

To integrate auditory and visual signals into a unified percept, the paired stimuli must co-occur within a limited time window known as the Temporal Binding Window (TBW). The width of the TBW, a proxy of audiovisual temporal integration ability, has been found to be correlated with higher-order cognitive and social functions. A comprehensive review of studies investigating audiovisual TBW reveals several findings: (1) a wide range of top-down processes and bottom-up features can modulate the width of the TBW, facilitating adaptation to the changing and multisensory external environment; (2) a large-scale brain network works in coordination to ensure successful detection of audiovisual (a)synchrony; (3) developmentally, audiovisual TBW follows a U-shaped pattern across the lifespan, with a protracted developmental course into late adolescence and rebounding in size again in late life; (4) an enlarged TBW is characteristic of a number of neurodevelopmental disorders; and (5) the TBW is highly flexible via perceptual and musical training. Interventions targeting the TBW may be able to improve multisensory function and ameliorate social communicative symptoms in clinical populations.

Brief Sensory Training Narrows the Temporal Binding Window and Enhances Long-Term Multimodal Speech Perception

Our ability to integrate multiple sensory-based representations of our surrounding supplies us with a more holistic view of our world. There are many complex algorithms our nervous system uses to construct a coherent perception. An indicator to solve this 'binding problem' are the temporal characteristics with the specificity that environmental information has different propagation speeds (e.g., sound and electromagnetic waves) and sensory processing time and thus the temporal relationship of a stimulus pair derived from the same event must be flexibly adjusted by our brain. This tolerance can be conceptualized in the form of the cross-modal temporal binding window (TBW). Several studies showed the plasticity of the TBW and its importance concerning audio-visual illusions, synesthesia, as well as psychiatric disturbances. Using three audio-visual paradigms, we investigated the importance of length (short vs. long) as well as modality (uni- vs. multimodal) of a perceptual training aiming at reducing the TBW in a healthy population. We also investigated the influence of the TBW on speech intelligibility, where participants had to integrate auditory and visual speech information from a videotaped speaker. We showed that simple sensory trainings can change the TBW and are capable of optimizing speech perception at a very naturalistic level. While the training-length had no different effect on the malleability of the TBW, the multisensory trainings induced a significantly stronger narrowing of the TBW than their unisensory counterparts. Furthermore, a narrowing of the TBW was associated with a better performance in speech perception, meaning that participants showed a greater capacity for integrating informations from different sensory modalities in situations with one modality impaired. All effects persisted at least seven days. Our findings show the significance of multisensory temporal processing regarding ecologically valid measures and have important clinical implications for interventions that may be used to alleviate debilitating conditions (e.g., autism, schizophrenia), in which multisensory temporal function is shown to be impaired.

Funktionaler Analphabetismus in Deutschland – Größenordnung, Ursachen, Interventionen

Zusammenfassung. Allein in Deutschland verfügen etwa 7.5 Millionen Erwachsene nicht über ausreichende Lese- und Schreibkompetenzen, um in angemessener Weise am gesellschaftlichen Leben teilhaben zu können. Sie können maximal kurze, einfache Texte sinnentnehmend lesen. Diese Personen werden häufig als funktionale Analphabetinnen und Analphabeten bezeichnet. Die Arbeit gibt einen Überblick zu Größenordnung, Ursachen und Interventionsmöglichkeiten bei funktionalem Analphabetismus. Es wird ein biopsychosoziales Ursachenmodell vorgestellt, das biologische Vulnerabilitätsfaktoren postuliert, die unter ungünstigen psychosozialen Bedingungen zu einer erhöhten Wahrscheinlichkeit für die Entwicklung von Lese- und Schreibproblemen führen. Weiterhin wird auf Unterschiede zwischen und Gemeinsamkeiten von funktionalem Analphabetismus und Lese-Rechtschreib-Störung (LRS) eingegangen. Abschließend werden aktuelle Entwicklungen von Trainingsprogrammen zur Förderung der Lese- und Rechtschreibfähigkeiten von Erwachsenen, häufig im Kontext von Grundbildungsprogrammen, beschrieben.

Ripe for solution: Delayed development of multisensory processing in autism and its remediation

Difficulty integrating inputs from different sensory sources is commonly reported in individuals with Autism Spectrum Disorder (ASD). Accumulating evidence consistently points to altered patterns of behavioral reactions and neural activity when individuals with ASD observe or act upon information arriving through multiple sensory systems. For example, impairments in the integration of seen and heard speech appear to be particularly acute, with obvious implications for interpersonal communication. Here, we explore the literature on multisensory processing in autism with a focus on developmental trajectories. While much remains to be understood, some consistent observations emerge. Broadly, sensory integration deficits are found in children with an ASD whereas these appear to be much ameliorated, or even fully recovered, in older teenagers and adults on the spectrum. This protracted delay in the development of multisensory processing raises the possibility of applying early intervention strategies focused on multisensory integration, to accelerate resolution of these functions. We also consider how dysfunctional cross-sensory oscillatory neural communication may be one key pathway to impaired multisensory processing in ASD.