Visual perceptual load reduces auditory detection in typically developing individuals but not in individuals with Autism Spectrum Disorders

Objective: Previous studies examining selective attention in individuals with autism spectrum disorder (ASD) have yielded conflicting results, some suggesting superior focused attention (e.g. on visual search tasks), others demonstrating greater distractibility. This pattern could be accounted for by the proposal (derived by applying the Load theory of attention, e.g. Lavie, 2005) that ASD is characterized by an increased perceptual capacity (Remington, Swettenham, Campbell, & Coleman, 2009). Recent studies in the visual domain support this proposal. Here we hypothesize that ASD involves an enhanced perceptual capacity that also operates across sensory modalities, and test this prediction, for the first time using a signal detection paradigm. Method: 17 neurotypical (NT) and 15 ASD adolescents performed a visual search task under varying levels of visual perceptual load while simultaneously detecting presence/absence of an auditory tone embedded in noise. Results: Detection sensitivity (d’) for the auditory stimulus was similarly high for both groups in the low visual perceptual load condition (e.g. 2 items: p = .391, d = 0.31, 95% CI [-.39, 1.00]). However, at a higher level of visual load, auditory d’ reduced for the NT group but not the ASD group leading to a group difference (p = .002, d = 1.2, 95% CI [.44, 1.96]). As predicted, when visual perceptual load was highest, both groups then showed a similarly low auditory d’ (p = .9, d = 0.05, 95% CI [-.65, .74]). Conclusions: These findings demonstrate that increased perceptual capacity in ASD operates across modalities

Under-reactive but easily distracted: An fMRI investigation of attentional capture in autism spectrum disorder

For individuals with autism spectrum disorder (ASD), salient behaviorally-relevant information often fails to capture attention, while subtle behaviorally-irrelevant details commonly induce a state of distraction. The present study used functional magnetic resonance imaging (fMRI) to investigate the neurocognitive networks underlying attentional capture in sixteen high-functioning children and adolescents with ASD and twenty-one typically developing (TD) individuals. Participants completed a rapid serial visual presentation paradigm designed to investigate activation of attentional networks to behaviorally-relevant targets and contingent attention capture by task-irrelevant distractors. In individuals with ASD, target stimuli failed to trigger bottom-up activation of the ventral attentional network and the cerebellum. Additionally, the ASD group showed no differences in behavior or occipital activation associated with contingent attentional capture. Rather, results suggest that to-be-ignored distractors that shared either task-relevant or irrelevant features captured attention in ASD. Results indicate that individuals with ASD may be under-reactive to behaviorally-relevant stimuli, unable to filter irrelevant information, and that both top-down and bottom-up attention networks function atypically in ASD. Lastly, deficits in target-related processing were associated with autism symptomatology, providing further support for the hypothesis that non-social attentional processes and their neurofunctional underpinnings may play a significant role in the development of sociocommunicative impairments in ASD. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-NDlicense

Perceptual and Cognitive Load in Autism – An Electrophysiological and Behavioural Approach

Attention is a fundamentally important cognitive process and is required to efficiently navigate the world. Whilst altered attentional processes have been frequently observed in autistic people the differences seen suggest that attentional processes are different, however not necessarily deficient. In fact, aspects of superior visual perceptual ability and enhanced perceptual capacity have frequently been reported. The goal of the present thesis was to extend our knowledge of enhanced perceptual capacity under the framework of the Load Theory and to extend the findings to more active components of attention. To address this aim, the first three empirical studies I conducted, assessed selective and executive attention in autism and in a fourth study I investigated the feasibility of a neurofeedback intervention. Specifically, in Chapter 2, I used behavioural markers of congruency effects to consider whether cognitive capacity would be increased for autistic people, analogous to the enhanced perceptual capacity previously reported. In Chapter 3, I investigated electrophysiological aspects of visual working memory capacity and filtering efficiency. The findings were further expanded upon in Chapter 4 by directly contrasting visual working memory capacity and perceptual capacity using electrophysiological markers. Finally, I sought to assess whether practical steps could be taken to address altered attention experienced by autistic adults. The feasibility of an online neurofeedback intervention was investigated to assess whether aspects of attention and mental health could be improved through the training programme (Chapter 5). The findings of the thesis were then summarised and further discussed, highlighting the contribution to the autism attention literature and offering practical recommendations to harness attentional strengths in autism

Twenty years of load theory—Where are we now, and where should we go next?

Selective attention allows us to ignore what is task-irrelevant and focus on what is task-relevant. The cognitive and neural mechanisms that underlie this process are key topics of investigation in cognitive psychology. One of the more prominent theories of attention is perceptual load theory, which suggests that the efficiency of selective attention is dependent on both perceptual and cognitive load. It is now more than 20 years since the proposal of load theory, and it is a good time to evaluate the evidence in support of this influential model. The present article supplements and extends previous reviews (Lavie, Trends in Cognitive Sciences, 9, 75–82. doi:10.​1016/​j.​tics.​2004.​12.​004, 2005, Current Directions in Psychological Science, 19, 143–148. doi:10.​1177/​0963721410370295​, 2010) by examining more recent research in what appears to be a rapidly expanding area. The article comprises five parts, examining (1) evidence for the effects of perceptual load on attention, (2) cognitive load, (3) individual differences under load, (4) alternative theories and criticisms, and (5) the future of load theory. We argue that the key next step for load theory will be the application of the model to real-world tasks. The potential benefits of applied attention research are numerous, and there is tentative evidence that applied research would provide strong support for the theory itself, as well as real-world benefits related to activities in which attention is crucial, such as driving and education

The neurophysiology of intersensory selective attention and task switching

Our ability to selectively attend to certain aspects of the world and ignore others is fundamental to our day-to-day lives. The need for selective attention stems from capacity limitations inherent in our perceptual and cognitive processing architecture. Because not every elemental piece of our environment can be fully processed in parallel, the nervous system must prioritize processing. This prioritization is generally referred to as selective attention. Meanwhile, we are faced with a world that is constantly in flux, such that we have to frequently shift our attention from one piece of the environment to another and from one task to another. This process is generally referred to as task-switching. Neural oscillations in the alpha band (~8-14 Hz) have been shown to index the distribution of selective attention, and there is increasing evidence that oscillations in this band are in fact utilized by the nervous system to suppress distracting, task-irrelevant information. In order to elaborate on what is known of the function of alpha oscillations as well as current models of both intersensory selective attention and task switching, I investigated the dynamics of alpha amplitude modulations within the context of intersenory selective attention and task switching in neurologically typical young adults. Participants were alternately cued to attend to either the visual or auditory aspect of a compound audio-visual stimulus while high-density electroencephalography was recorded. It is typically found that alpha power increases over parieto-occipital cortices when attention is directed away from the visual modality and to the auditory modality. I report evidence that alpha oscillations play a role in task-switching (e.g., when switching from attending the visual task versus repeating this task), specifically as biasing signals, that may operate to re-weight competition among two tasks-sets. I further investigated the development of these same processes in school-aged children and adolescents. While exhibiting typical patterns of alpha modulations relevant to selective attention, Young school-aged children (8-12 years), compared to older participants, did not demonstrate specific task switching modulation of alpha oscillations, suggesting that this process does not fully develop until late adolescence. Finally, children and adolescents on the autism spectrum failed altogether to exhibit differentiation of alpha power between attend-visual and attend-auditory conditions--an effect present in age and IQ matched controls--suggesting that ASD individuals may have a deficit in the overall top-down deployment of alpha oscillatory biasing signals. This could result in an inability to ignore distracting information in the environment, leading to an overwhelming, disordered experience of the world, resulting in profound effects on the both social interaction and cognitive development. Altogether, these findings add to growing evidence that alpha oscillations serve as domain general biasing signals and are integral to our flexible goal-oriented behavior. Furthermore, the flexible use of these biasing signals in selective attention and task switching develops over a protracted period, and appears to be aberrant in autism spectrum disorder

Examining the relationship between sensory processing and attention in individuals with autism spectrum disorders

2017 Fall.Includes bibliographical references.Attention is a crucial element of our goal-directed, purposeful response to sensory information in our social and physical environments. Individuals with autism spectrum disorders (ASD) have significant deficits in sensory processing and attention. However, there is limited research examining the relationship between attention and sensory processing in individuals with autism spectrum disorders (ASD). The purpose of this dissertation was to examine the relationship between attention and sensory processing in individuals with autism spectrum disorders (ASD) and neurotypical individuals. Specifically, the objective was to examine if consciously directing attention to incoming information would result in more typical neural processing in individuals with ASD. To answer this question, study 1 was designed to understand how attention and distraction impacted sensory processing in neurotypical individuals. Studies 2 and 3 examined neural measures of sensory processing in individuals with ASD as compared to age-matched neurotypical controls during passive and active attentional states. In Study 1, electroencephalography (EEG) data were recorded while 60 adults (18-35 years) heard random presentations of 4 auditory stimuli at 2 frequencies (1 and 3 kHz) each at 2 intensities (50 and 70 dB). Participants were randomly divided into 2 viewing conditions; one group watched a silent movie and the other viewed a fixation point during the recording. All participants completed 2 attention conditions, the passive condition involved only listening to the stimuli, followed by the active condition, wherein participants were instructed to press a button to the 1 kHz 50 dB tone. Amplitude and latency measures were obtained for the N1, P2, N2, and P3 components for each of the auditory stimuli. The ANOVAs revealed a significant main effect of attention condition for the N1, P2, N2, and P3 amplitudes. There were also significant attention-by-viewing condition interaction effects at the P3 component. Results indicated that actively directing attention to the tones impacts auditory processing at all components. Additionally, manipulation of attention by changing the viewing environment significantly interacted with sensory processing, such that movie viewing resulted in larger P3 amplitudes compared with fixation viewing. Thus, viewing environment or distraction impacts sensory processing. In study 2, we examined the effect of attention on auditory filtering using the sensory gating paradigm in individuals with ASD. EEG data were recorded during 2 attention conditions from 24 adults with ASD and 24 neurotypical individuals during the sensory gating paradigm. During the passive condition, participants were presented with single and paired clicks. For the active condition, participants made a motor response following the single click but not the paired click. Attending to the clicks resulted in larger P50 and N1 amplitudes, and reduced gating for all participants. Although, the ASD group had P50 and N1 gating during both attention conditions, they had significantly longer N1 latencies to the Click 1 during both the attention conditions, suggesting a delayed orienting response. However, click 2 latencies were delayed only in the passive condition and not the active condition for the ASD group compared to the neurotypical group. This finding suggests of attention-based amelioration of processing speed in individuals with ASD. Individuals with ASD also had significantly more deficits on behavioral measures of social responsivity, attention, sensory and perceptual processing. Additionally, neural measures of gating were associated with several behavioral measures of sensory processing as measured by self-report questionnaires and a performance-based measure of attention, such that efficient neural processing was associated with more typical sensory processing and attention. In study 3, we examined the effect of attention on auditory discrimination in individuals with ASD. EEG data were recorded from 24 individuals with ASD and 24 neurotypical individuals, while they heard random presentations of 4 auditory stimuli at 2 different frequencies (1 and 3 kHz) each at 2 different intensities (50 and 70 dB). All participants completed two attention conditions; the passive condition involved only listening to the stimuli, followed by the active condition, wherein participants were instructed to press a button to the 1 kHz 50 dB tone. Attention impacted N2, and P3 amplitudes, and P2 and N2 latencies. The ASD group had significantly longer N1, N2, and P3 latencies, suggesting delayed processing. N2 and P3 latency delays in the ASD group were present during the passive but not active condition, implying an attention-based amelioration of processing delay. Behavioral measures of sensory processing and attention correlated with neural measures of auditory processing. Thus, through the series of studies, we found that actively directing attention to the tones impacts auditory processing, and may result in more typical processing in ASD. The study findings also suggest that sensory processing deficits observed in ASD may be associated with underlying deficits of attention. Study findings have significant implications related to understanding auditory discrimination in individuals with ASD and examining the impact of attention on sensory processing. Additionally, these results can help practitioners understand the neural basis of behavioral manifestations of ASD, especially those atypical behaviors that occur in response to sensory experiences in everyday activities

Neural measures of visual attention and suppression as biomarkers for ADHD-associated inattention

Whilst there is a wealth of literature examining neural differences in those with ADHD, few have investigated visual-associated regions. Given extensive evidence demonstrating visual-attention deficits in ADHD, it is possible that inattention problems may be associated with functional abnormalities within the visual system. By measuring neural responses across the visual system during visual-attentional tasks, we aim to explore the relationship between visual processing and ADHD-associated Inattention in the typically developed population. We first explored whether differences in neural responses occurred within the superior colliculus (SC); an area linked to distractibility and attention. Here we found that Inattention traits positively correlated with SC activity, but only when distractors were presented in the right visual field (RVF) and not the left visual field (LVF). Our later work followed up on these findings to investigate separate responses towards task-relevant targets and irrelevant, peripheral distractors. Findings showed that those with High Inattention exhibited increased responses towards distractors compared to targets, while those with Low Inattention showed the opposite effect. Hemifield differences were also observed where those with High Inattention showed increased RVF distractor-related signals compared to those with Low Inattention. No differences were observed for the LVF. Finally, we examined attention and suppression-related neural responses. Our results indicated that, while attentional responses were similar between Inattention groups, those with High Inattention showed weaker suppression responses towards the unattended RVF. No differences were found when suppressing the LVF. Findings across all studies suggest that differences in neural responses between those with High and Low levels of Inattention exist within the visual system. Such differences appear to relate to suppression of task-irrelevant distractors rather than attention towards task-relevant targets, suggesting such mechanisms are differentially affected in those with frequent Inattention problems. We also show a clear relationship between Inattention traits and visual suppression of the RVF

Alpha and gamma-band oscillations in MEG-data: networks, function and development

Die Adoleszenz, d.h. die Reifungsphase des Jugendlichen zum Erwachsenen, stellt einen zentralen Abschnitt in der menschlichen Entwicklung dar, der mit tief greifenden emotionalen und kognitiven Veränderungen verbunden ist. Neure Studien (Bunge et al., 2002; Durston et al., 2002; Casey et al., 2005; Crone et al., 2006; Bunge and Wright, 2007) machen deutlich, dass sich die funktionelle Architektur des Gehirns während der Adoleszenz grundlegend verändert und dass diese Veränderungen mit der Reifung höherer kognitiven Funktionen in der Adoleszenz assoziiert sein könnten. Messungen des Gehirn-Volumens mit Hilfe der Magnet-Resonanz-Tomographie (MRT) zum Beispiel zeigen eine nicht-lineare Reduktion der grauen und eine Zunahme der weißen Substanz während der Adoleszenz (Giedd et al., 1999; Sowell et al., 1999, 2003). Des weiteren treten in dieser Zeit Veränderungen in exzitatorischen und inhibitorischen Neurotransmitter-Systemen auf (Tseng and O’Donnell, 2005; Hashimoto et al., 2009). Zusammen deuten diese Ergebnisse darauf hin, dass während der Adoleszenz ein Umbau der kortikalen Netzwerke stattfindet, der wichtige Konsequenzen für die Reifung neuronaler Oszillationen haben könnte. Im Anschluss an eine Einführung im Kapitel 2, fasst Kapitel 3 der vorliegenden Dissertation die Vorbefunde bezüglich entwicklungsbedingter Veränderungen in der Amplitude, Frequenz und Synchronisation neuronaler Oszillationen zusammen und diskutiert den Zusammenhang zwischen der Entwicklung neuronaler Oszillationen und der Reifung höhere kognitiver Funktionen während der Adoleszenz. Ebenso werden die anatomischen und physiologischen Mechanismen, die diesen Veränderungen möglicherweise zu Grunde liegen könnten, theoretisch vorgestellt. Die in Kapitel 4-6 vorgestellten eigenen empirischen Arbeiten untersuchen neuronale Oszillationen mit Hilfe der Magnetoencephalographie (MEG), um die Frequenzbänder und die funktionellen Netzwerke zu charakterisieren, die mit höheren kognitiven Prozessen und deren Entwicklung in der Adoleszenz assoziiert sind. Hierzu wurden drei Experimente durchgeführt, bei denen MEG-Aktivität während der Bearbeitung einer Arbeitsgedächtnisaufgabe und im Ruhezustand aufgezeichnet wurde. Die Ergebnisse dieser Experimente zeigen, dass Alpha Oszillationen und Gamma-Band Aktivität sowohl task-abhängig als auch im Ruhezustand gemeinsam auftreten. Darüber hinaus ergänzen die vorliegenden Untersuchungen Vorarbeiten, indem sie eine Wechselwirkung zwischen beiden Frequenzbändern aufgezeigt wird, die als ein Mechanismus für das gezielte Weiterleiten von Informationen dienen könnte. Die in Kapitel 6 vorgestellten Entwicklungsdaten weisen weiterhin darauf, dass in der Adoleszenz späte Veränderungen im Alpha und Gamma-Band stattfinden und dass diese Veränderungen involviert sind in die Entwicklung der Arbeitsgedächtnis-Kapazität und die Entwicklung der Fähigkeit, Distraktoren zu inhibieren. Abschliessend werden in Kapitel 7, die in dieser Dissertation vorgestellten Arbeiten, aus einer übergeordneten Perspektive im Gesamtzusammenhang diskutiert

Selective attention and perceptual load in autism spectrum disorder

This thesis examines selective attention in young adults with Autism Spectrum Disorder (ASD). Existing literature regarding this issue is mixed; some research suggesting an overly-focused attentional style (Rincover & Ducharme, 1987) while others highlight an abnormally broad attentional lens (Burack, 1994). The research presented here has, for the first time, examined selective attention in individuals with ASD using a theoretically-led approach based on Lavie’s Load Theory of attention and cognitive control (Lavie et al., 2004). Load theory states that the perceptual load (amount of potentially task relevant information) of a task affects selective attention. This theory may explain the equivocal findings in the current data on selective attention and ASD. Using behavioural measures, the pattern of selective attention under various levels of load was explored in individuals with ASD and matched controls. The results provide evidence of increased perceptual capacity in ASD. This means that, at any one time, individuals with ASD may be able to process more information from the visual environment. This increase in capacity was evident on tasks of both unconscious and conscious perception. In light of the social deficits observed in the condition, the work in this thesis also explored selective attention in the presence of social distractor stimuli. Results indicated that faces are less salient for individuals with ASD and, unlike for typical adults, are not processed in an automatic and mandatory fashion. These results bring together findings on selective attention with work on social processing in an attempt to find basic abnormalities which might be fundamental in explaining the disorder