Auditory attention to frequency and time: an analogy to visual local-global stimuli

Global-Local Processing in ADHD Is Not Limited to the Visuospatial Domain: Novel Evidence From the Auditory Domain

OBJECTIVE

Global-local visuospatial processing has been widely investigated in both healthy and clinical populations. Recent studies indicated that individuals with ADHD lack a global processing bias. However, the extant literature regarding global-local processing style focuses solely on the visual modality.

METHODS

ADHD (N = 21) and typically developed (TD) controls (N = 24) underwent an auditory global-local task, in which they had to decide whether the melody is ascending or descending in global or local conditions.

RESULTS

TD controls exhibited a classic global processing bias in the auditory task. The ADHD group exhibited no global processing bias, indicating similar processing for global and local dimensions, implying that individuals with ADHD are distracted by incongruent information in global and local conditions similarly, in both visual and auditory tasks.

CONCLUSION

A lack of global processing bias in ADHD is not limited to the visuospatial modality and likely reflects a broader and more general processing style.

Auditory Pitch Perception in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis

PURPOSE

Pitch plays an important role in auditory perception of music and language. This study provides a systematic review with meta-analysis to investigate whether individuals with autism spectrum disorder (ASD) have enhanced pitch processing ability and to identify the potential factors associated with processing differences between ASD and neurotypicals.

METHOD

We conducted a systematic search through six major electronic databases focusing on the studies that used nonspeech stimuli to provide a qualitative and quantitative assessment across existing studies on pitch perception in autism. We identified potential participant- and methodology-related moderators and conducted metaregression analyses using mixed-effects models.

RESULTS

On the basis of 22 studies with a total of 464 participants with ASD, we obtained a small-to-medium positive effect size (g = 0.26) in support of enhanced pitch perception in ASD. Moreover, the mean age and nonverbal IQ of participants were found to significantly moderate the between-studies heterogeneity.

CONCLUSIONS

Our study provides the first meta-analysis on auditory pitch perception in ASD and demonstrates the existence of different developmental trajectories between autistic individuals and neurotypicals. In addition to age, nonverbal ability is found to be a significant contributor to the lower level/local processing bias in ASD. We highlight the need for further investigation of pitch perception in ASD under challenging listening conditions. Future neurophysiological and brain imaging studies with a longitudinal design are also needed to better understand the underlying neural mechanisms of atypical pitch processing in ASD and to help guide auditory-based interventions for improving language and social functioning.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21614271.

Global and local priming in a multi-modal context

Perceptual information can be processed at many different scales, from featural details to entire scenes. Attentional selection of different scales has been studied using hierarchical stimuli, with research elucidating a variety of biases in local and global attentional selection (due to, e.g., stimulus properties, brain injury, and experience). In this study, the emphasis is on biases produced through recent experience, or level-specific priming effects, which have been demonstrated within both the visual and auditory modalities. Namely, when individuals attend to local information, they are subsequently biased to attend locally (and similarly so with global attention). Here, these level-specific priming effects are investigated in a multi-modal context to determine whether cross-modal interactions occur between visual and auditory modalities during hierarchical processing. Specifically, the study addresses if attentional selection of local or global information in the visual modality subsequently biases auditory attentional selection to that level, and vice versa (i.e., level-priming). Though expected identity priming effects emerged in the study, no cross-modal level-priming effects manifested. Furthermore, the multi-modal context eliminated the well-established within-modality level-specific priming effects. Thus, though the study does reveal a multi-modal effect, it was not a level-based effect. Instead, paradoxically, the multi-modal context eliminated attentional scope biases (i.e., level-priming) within uni-modal transitions. In other words, when visual and auditory information are equally likely require attention, no persistence emerges for processing local or global information over time, even within a single modality.

Auditory local-global temporal processing: evidence for perceptual reorganization with musical expertise

The way the visual system processes different scales of spatial information has been widely studied, highlighting the dominant role of global over local processing. Recent studies addressing how the auditory system deals with local–global temporal information suggest a comparable processing scheme, but little is known about how this organization is modulated by long-term musical training, in particular regarding musical sequences. Here, we investigate how non-musicians and expert musicians detect local and global pitch changes in short hierarchical tone sequences structured across temporally-segregated triplets made of musical intervals (local scale) forming a melodic contour (global scale) varying either in one direction (monotonic) or both (non-monotonic). Our data reveal a clearly distinct organization between both groups. Non-musicians show global advantage (enhanced performance to detect global over local modifications) and global-to-local interference effects (interference of global over local processing) only for monotonic sequences, while musicians exhibit the reversed pattern for non-monotonic sequences. These results suggest that the local–global processing scheme depends on the complexity of the melodic contour, and that long-term musical training induces a prominent perceptual reorganization that reshapes its initial global dominance to favour local information processing. This latter result supports the theory of “analytic” processing acquisition in musicians.

A Tendency Towards Details? Inconsistent Results on Auditory and Visual Local-To-Global Processing in Absolute Pitch Musicians

Absolute pitch, the ability to name or produce a musical tone without a reference, is a rare ability which is often related to early musical training and genetic components. However, it remains a matter of debate why absolute pitch is relatively common in autism spectrum disorders and why absolute pitch possessors exhibit higher autistic traits. By definition absolute pitch is an ability that does not require the relation of tones but is based on a lower-level perceptual entity than relative pitch (involving relations between tones, intervals, and melodies). This study investigated whether a detail-oriented cognitive style, a concept borrowed from the autism literature (weak central coherence theory), might provide a framework to explain this joint occurrence. Two local-to-global experiments in vision (hierarchically constructed letters) and audition (hierarchically constructed melodies) as well as a pitch adjustment test measuring absolute pitch proficiency were conducted in 31 absolute pitch and 33 relative pitch professional musicians. Analyses revealed inconsistent group differences among reaction time, total of correct trials and speed-accuracy-composite-scores of experimental conditions (local vs. global, and congruent vs. incongruent stimuli). Furthermore, amounts of interference of global form on judgments of local elements and vice versa were calculated. Interestingly, reduced global-to-local interference in audition was associated with greater absolute pitch ability and in vision with higher autistic traits. Results are partially in line with the idea of a detail-oriented cognitive style in absolute pitch musicians. The inconsistency of the results might be due to limitations of global-to-local paradigms in measuring cognitive style and due to heterogeneity of absolute pitch possessors. In summary, this study provides further evidence for a multifaceted pattern of various and potentially interacting factors on the acquisition of absolute pitch.

Auditory Pitch Perception in Autism Spectrum Disorder Is Associated With Nonverbal Abilities

Atypical sensory perception and heterogeneous cognitive profiles are common features of autism spectrum disorder (ASD). However, previous findings on auditory sensory processing in ASD are mixed. Accordingly, auditory perception and its relation to cognitive abilities in ASD remain poorly understood. Here, children with ASD, and age- and intelligence quotient (IQ)-matched typically developing children, were tested on a low- and a higher level pitch processing task. Verbal and nonverbal cognitive abilities were measured using the Wechsler's Abbreviated Scale of Intelligence. There were no group differences in performance on either auditory task or IQ measure. However, there was significant variability in performance on the auditory tasks in both groups that was predicted by nonverbal, not verbal skills. These results suggest that auditory perception is related to nonverbal reasoning rather than verbal abilities in ASD and typically developing children. In addition, these findings provide evidence for preserved pitch processing in school-age children with ASD with average IQ, supporting the idea that there may be a subgroup of individuals with ASD that do not present perceptual or cognitive difficulties. Future directions involve examining whether similar perceptual-cognitive relationships might be observed in a broader sample of individuals with ASD, such as those with language impairment or lower IQ.

Simultanagnosia does not affect processes of auditory Gestalt perception

Simultanagnosia is a neuropsychological deficit of higher visual processes caused by temporo-parietal brain damage. It is characterized by a specific failure of recognition of a global visual Gestalt, like a visual scene or complex objects, consisting of local elements. In this study we investigated to what extend this deficit should be understood as a deficit related to specifically the visual domain or whether it should be seen as defective Gestalt processing per se. To examine if simultanagnosia occurs across sensory domains, we designed several auditory experiments sharing typical characteristics of visual tasks that are known to be particularly demanding for patients suffering from simultanagnosia. We also included control tasks for auditory working memory deficits and for auditory extinction. We tested four simultanagnosia patients who suffered from severe symptoms in the visual domain. Two of them indeed showed significant impairments in recognition of simultaneously presented sounds. However, the same two patients also suffered from severe auditory working memory deficits and from symptoms comparable to auditory extinction, both sufficiently explaining the impairments in simultaneous auditory perception. We thus conclude that deficits in auditory Gestalt perception do not appear to be characteristic for simultanagnosia and that the human brain obviously uses independent mechanisms for visual and for auditory Gestalt perception.

The Role of Musical Experience in Hemispheric Lateralization of Global and Local Auditory Processing

The global precedence effect is a phenomenon in which global aspects of visual and auditory stimuli are processed before local aspects. Individuals with musical experience perform better on all aspects of auditory tasks compared with individuals with less musical experience. The hemispheric lateralization of this auditory processing is less well-defined. The present study aimed to replicate the global precedence effect with auditory stimuli and to explore the lateralization of global and local auditory processing in individuals with differing levels of musical experience. A total of 38 college students completed an auditory-directed attention task while electroencephalography was recorded. Individuals with low musical experience responded significantly faster and more accurately in global trials than in local trials regardless of condition, and significantly faster and more accurately when pitches traveled in the same direction (compatible condition) than when pitches traveled in two different directions (incompatible condition) consistent with a global precedence effect. In contrast, individuals with high musical experience showed less of a global precedence effect with regards to accuracy, but not in terms of reaction time, suggesting an increased ability to overcome global bias. Further, a difference in P300 latency between hemispheres was observed. These findings provide a preliminary neurological framework for auditory processing of individuals with differing degrees of musical experience.

Effects of Age and Attention on Auditory Global-Local Processing in Children with Autism Spectrum Disorder

In vision, typically-developing (TD) individuals perceive "global" (whole) before "local" (detailed) features, whereas individuals with autism spectrum disorder (ASD) exhibit a local bias. However, auditory global-local distinctions are less clear in ASD, particularly in terms of age and attention effects. To these aims, here ASD and TD children judged local and global pitch structure in nine-tone melodies. Both groups showed a similar global precedence effect, but ASD children were less sensitive to global interference than TD children at younger ages. There was no effect of attention task. These findings provide novel evidence of developmental differences in auditory perception and may help to refine sensory phenotypes in ASD.

Testing multi-scale processing in the auditory system

Natural sounds contain information on multiple timescales, so the auditory system must analyze and integrate acoustic information on those different scales to extract behaviorally relevant information. However, this multi-scale process in the auditory system is not widely investigated in the literature, and existing models of temporal integration are mainly built upon detection or recognition tasks on a single timescale. Here we use a paradigm requiring processing on relatively 'local' and 'global' scales and provide evidence suggesting that the auditory system extracts fine-detail acoustic information using short temporal windows and uses long temporal windows to abstract global acoustic patterns. Behavioral task performance that requires processing fine-detail information does not improve with longer stimulus length, contrary to predictions of previous temporal integration models such as the multiple-looks and the spectro-temporal excitation pattern model. Moreover, the perceptual construction of putatively 'unitary' auditory events requires more than hundreds of milliseconds. These findings support the hypothesis of a dual-scale processing likely implemented in the auditory cortex.

Auditory local bias and reduced global interference in autism

Processing local elements of hierarchical patterns at a superior level and independently from an intact global influence is a well-established characteristic of autistic visual perception. However, whether this confirmed finding has an equivalent in the auditory modality is still unknown. To fill this gap, 18 autistics and 18 typical participants completed a melodic decision task where global and local level information can be congruent or incongruent. While focusing either on the global (melody) or local level (group of notes) of hierarchical auditory stimuli, participants have to decide whether the focused level is rising or falling. Autistics showed intact global processing, a superior performance when processing local elements and a reduced global-to-local interference compared to typical participants. These results are the first to demonstrate that autistic processing of auditory hierarchical stimuli closely parallels processing of visual hierarchical stimuli. When analyzing complex auditory information, autistic participants present a local bias and a more autonomous local processing, but not to the detriment of global processing.

The role of pitch and temporal diversity in the perception and production of musical sequences

In two experiments we explored how the dimensions of pitch and time contribute to the perception and production of musical sequences. We tested how dimensional diversity (the number of unique categories in each dimension) affects how pitch and time combine. In Experiment 1, 18 musically trained participants rated the complexity of sequences varying only in their diversity in pitch or time; a separate group of 18 pianists reproduced these sequences after listening to them without practice. Overall, sequences with more diversity were perceived as more complex, but pitch diversity influenced ratings more strongly than temporal diversity. Further, although participants perceived sequences with high levels of pitch diversity as more complex, errors were more common in the sequences with higher diversity in time. Sequences in Experiment 2 exhibited diversity in both pitch and time; diversity levels were a subset of those tested in Experiment 1. Again diversity affected complexity ratings and errors, but there were no statistical interactions between dimensions. Nonetheless, pitch diversity was the primary factor in determining perceived complexity, and again temporal errors occurred more often than pitch errors. Additionally, diversity in one dimension influenced error rates in the other dimension in that both error types were more frequent relative to Experiment 1. These results suggest that although pitch and time do not interact directly, they are nevertheless not processed in an informationally encapsulated manner. The findings also align with a dimensional salience hypothesis, in which pitch is prioritised in the processing of typical Western musical sequences.

Auditory global-local processing: effects of attention and musical experience

In vision, global (whole) features are typically processed before local (detail) features ("global precedence effect"). However, the distinction between global and local processing is less clear in the auditory domain. The aims of the present study were to investigate: (i) the effects of directed versus divided attention, and (ii) the effect musical training on auditory global-local processing in 16 adult musicians and 16 non-musicians. Participants were presented with short nine-tone melodies, each comprised of three triplet sequences (three-tone units). In a "directed attention" task, participants were asked to focus on either the global or local pitch pattern and had to determine if the pitch pattern went up or down. In a "divided attention" task, participants judged whether the target pattern (up or down) was present or absent. Overall, global structure was perceived faster and more accurately than local structure. The global precedence effect was observed regardless of whether attention was directed to a specific level or divided between levels. Musicians performed more accurately than non-musicians overall, but non-musicians showed a more pronounced global advantage. This study provides evidence for an auditory global precedence effect across attention tasks, and for differences in auditory global-local processing associated with musical experience.

Auditory-musical processing in autism spectrum disorders: a review of behavioral and brain imaging studies

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by atypical social and communication skills, repetitive behaviors, and atypical visual and auditory perception. Studies in vision have reported enhanced detailed ("local") processing but diminished holistic ("global") processing of visual features in ASD. Individuals with ASD also show enhanced processing of simple visual stimuli but diminished processing of complex visual stimuli. Relative to the visual domain, auditory global-local distinctions, and the effects of stimulus complexity on auditory processing in ASD, are less clear. However, one remarkable finding is that many individuals with ASD have enhanced musical abilities, such as superior pitch processing. This review provides a critical evaluation of behavioral and brain imaging studies of auditory processing with respect to current theories in ASD. We have focused on auditory-musical processing in terms of global versus local processing and simple versus complex sound processing. This review contributes to a better understanding of auditory processing differences in ASD. A deeper comprehension of sensory perception in ASD is key to better defining ASD phenotypes and, in turn, may lead to better interventions.

Global and local pitch perception in children with developmental dyslexia

This study investigated global versus local pitch pattern perception in children with dyslexia aged between 8 and 11 years. Children listened to two consecutive 4-tone pitch sequences while performing a same/different task. On the different trials, sequences either preserved the contour (local condition) or they violated the contour (global condition). Compared to normally developing children, dyslexics showed robust pitch perception deficits in the local but not the global condition. This finding was replicated in a simple pitch direction task, which minimizes sequencing and short term memory. Results are consistent with a left-hemisphere deficit in dyslexia because local pitch changes are supposedly processed by the left hemisphere, whereas global pitch changes are processed by the right hemisphere. The present data suggest a link between impaired pitch processing and abnormal phonological development in children with dyslexia, which makes pitch pattern processing a potent tool for early diagnosis and remediation of dyslexia.

Global precedence effect in audition and vision: evidence for similar cognitive styles across modalities

This study aimed to provide evidence for a Global Precedence Effect (GPE) in both vision and audition modalities. In order to parallel Navon's paradigm, a novel auditory task was designed in which hierarchical auditory stimuli were used to involve local and global processing. Participants were asked to process auditory and visual hierarchical patterns at the local or global level. In both modalities, a global-over-local advantage and a global interference on local processing were found. The other compelling result is a significant correlation between these effects across modalities. Evidence that the same participants exhibit similar processing style across modalities strongly supports the idea of a cognitive style to process information and common processing principle in perception.

Modulation of non-spatial attention and the global/local processing bias

Amelioration of the rightward spatial attention bias in patients with hemispatial neglect following manipulations of non-spatial attention suggests that spatial attention and mechanisms related to the regulation of attention are interrelated. Studies in normal, healthy subjects have shown similar modulation in spatial bias following tonic and phasic changes in attention suggesting that this interaction is a general mechanism of attention rather than a curiosity of the neglect disorder. The current study examined this attentional interaction to determine if perceptual processes favoring one hemisphere over the other are affected by this relationship. Participants first made rapid discriminations of Navon figures presented at central fixation. As expected, when participants attended to either the local or global dimension, incongruence in the orthogonal dimension resulted in longer reaction times for accurate discrimination compared to congruent trials. However, following a brief (16-min) continuous performance task designed to elicit behaviors associated with greater tonic and phasic alertness, participants showed significantly less local interference when attending the global dimension and more global interference when attending the local dimension on the Navon discrimination task compared to a control task condition. The results indicate that exercising tonic and phasic alertness produces a global processing bias.

Relative priming of temporal local--global levels in auditory hierarchical stimuli

Priming is a useful tool for ascertaining the circumstances under which previous experiences influence behavior. Previously, using hierarchical stimuli, we demonstrated (Justus & List, 2005) that selectively attending to one temporal scale of an auditory stimulus improved subsequent attention to a repeated (vs. changed) temporal scale; that is, we demonstrated intertrial auditory temporal level priming. Here, we have extended those results to address whether level priming relied on absolute or relative temporal information. Both relative and absolute temporal information are important in auditory perception: Speech and music can be recognized over various temporal scales but become uninterpretable to a listener when presented too quickly or slowly. We first confirmed that temporal level priming generalized over new temporal scales. Second, in the context of multiple temporal scales, we found that temporal level priming operates predominantly on the basis of relative, rather than absolute, temporal information. These findings are discussed in the context of expectancies and relational invariance in audition.

Global versus local processing of frequency-modulated tones in gerbils: an animal model of lateralized auditory cortex functions

Hemispheric asymmetries of speech and music processing might arise from more basic specializations of left and right auditory cortex (AC). It is not clear, however, whether such asymmetries are unique to humans, i.e., consequences of speech and music, or whether comparable lateralized AC functions exist in nonhuman animals, as evolutionary precursors. Here, we investigated the cortical lateralization of perception of linearly frequency-modulated (FM) tones in gerbils, a rodent species with human-like low-frequency hearing. Using a footshock-reinforced shuttle-box avoidance go/no-go procedure in a total of 178 gerbils, we found that (i) the discrimination of direction of continuous FM (rising versus falling sweeps, 250-ms duration) was impaired by right but not left AC lesions; (ii) the discrimination of direction of segmented FM (50-ms segments, 50-ms silent gaps, total duration 250 ms) was impaired by bilateral but not unilateral AC lesions; (iii) the discrimination of gap durations (10-30 ms) in segmented FM was impaired by left but not right AC lesions. AC lesions before and after training resulted in similar effects. Together, these experiments suggest that right and left AC, even in rodents, use different strategies in analyzing FM stimuli. Thus, the right AC, by using global cues, determines the direction of continuous and segmented FM but cannot discriminate gap durations. The left AC, by using local cues, discriminates gap durations and determines FM direction only when additional segmental information is available.

fMRI evidence for a cortical hierarchy of pitch pattern processing

Pitch patterns, such as melodies, consist of two levels of structure: a global level, comprising the pattern of ups and downs, or contour; and a local level, comprising the precise intervals that make up this contour. An influential neuropsychological model suggests that these two levels of processing are hierarchically linked, with processing of the global structure occurring within the right hemisphere in advance of local processing within the left. However, the predictions of this model and its anatomical basis have not been tested in neurologically normal individuals. The present study used fMRI and required participants to listen to consecutive pitch sequences while performing a same/different one-back task. Sequences, when different, either preserved (local) or violated (global) the contour of the sequence preceding them. When the activations for the local and global conditions were contrasted directly, additional activation was seen for local processing in right planum temporale and posterior superior temporal sulcus (pSTS). The presence of additional activation for local over global processing supports the hierarchical view that the global structure of a pitch sequence acts as a “framework” on which the local detail is subsequently hung. However, the lateralisation of activation seen in the present study, with global processing occurring in left pSTS and local processing occurring bilaterally, differed from that predicted by the neuroanatomical model. A re-examination of the individual lesion data on which the neuroanatomical model is based revealed that the lesion data equally well support the laterality scheme suggested by our data. While the present study supports the hierarchical view of local and global processing, there is an evident need for further research, both in patients and neurologically normal individuals, before an understanding of the functional lateralisation of local and global processing can be considered established.

The role of auditory memory traces in attention to frequency

Three cued signal detection experiments demonstrated a role for auditory memory traces in frequency selectivity. The extent to which the cue predicted the signal frequency affected the size of the advantage for signals at the cue frequency over those at distant frequencies when the cue-signal gap was 10 sec but not when it was 1 sec. Detection of occasional signals presented at uncued frequencies was enhanced when they matched the frequency of cues from recent trials. With "relative" cues, which were usually followed by signals at the musical fifth above the cue frequency, performance on occasional signals at the cue frequency was enhanced relative to other unexpected frequencies. These results suggest that, regardless of the listener's expectations and intentions, the detectability of a signal is enhanced if its frequency matches an existing memory trace. One form of voluntary attention to frequency may involve maintaining traces that would otherwise slowly decay.

Auditory priming of frequency and temporal information: effects of lateralised presentation

Asymmetric distribution of function between the cerebral hemispheres has been widely investigated in the auditory modality. The current approach borrows heavily from visual local-global research in an attempt to determine whether, as in vision, local-global auditory processing is lateralised. In vision, lateralised local-global processing likely relies on spatial frequency information. Drawing analogies between visual spatial frequency and auditory dimensions, two sets of auditory stimuli were developed. In the high-low stimulus set we manipulate frequency information, and in the fast-slow stimulus set we manipulate temporal information. The fast-slow stimuli additionally mimic visual hierarchical stimulus structure, in which the arrangement of local patterns determines the global pattern. Unlike previous auditory stimuli, the current stimulus sets contain the experimental flexibility of visual local-global hierarchical stimuli allowing independent manipulation of structural levels. Previous findings of frequency and temporal range priming were replicated. Additionally, by presenting stimuli monaurally, we found that priming of frequency ranges (but not temporal ranges) was found to vary by ear, supporting the contention that the hemispheres asymmetrically retain traces of prior frequency processing. These results contribute to the extensive literature revealing cerebral asymmetries for the processing of frequency information, and extend those results to the realm of priming.

Local and global auditory processing: behavioral and ERP evidence

Differential processing of local and global visual features is well established. Global precedence effects, differences in event-related potentials (ERPs) elicited when attention is focused on local versus global levels, and hemispheric specialization for local and global features all indicate that relative scale of detail is an important distinction in visual processing. Observing analogous differential processing of local and global auditory information would suggest that scale of detail is a general organizational principle of the brain. However, to date the research on auditory local and global processing has primarily focused on music perception or on the perceptual analysis of relatively higher and lower frequencies. The study described here suggests that temporal aspects of auditory stimuli better capture the local-global distinction. By combining short (40 ms) frequency modulated tones in series to create global auditory patterns (500 ms), we independently varied whether pitch increased or decreased over short time spans (local) and longer time spans (global). Accuracy and reaction time measures revealed better performance for global judgments and asymmetric interference that were modulated by amount of pitch change. ERPs recorded while participants listened to identical sounds and indicated the direction of pitch change at the local or global levels provided evidence for differential processing similar to that found in ERP studies employing hierarchical visual stimuli. ERP measures failed to provide evidence for lateralization of local and global auditory perception, but differences in distributions suggest preferential processing in more ventral and dorsal areas respectively.

A mismatch negativity study of local-global auditory processing

We used mismatch negativity (MMN) to examine structural encoding of local and global auditory patterns in perceptual memory. Unlike previous MMN studies of local-global auditory perceptual organization that used interval-contour stimuli, here we presented hierarchical stimuli in which local pattern organization formed global patterns. Importantly, our stimuli allowed independent manipulation of the two structural levels. In separate blocks, participants were exposed to frequent local standard patterns and rare local deviant patterns, or to frequent global standard patterns and rare global deviant patterns. Within each deviant pattern, the variation from the standard pattern could occur at onset (early), towards the end of the pattern (late) or over both time windows (both). To isolate pattern indexing at one level, the other level continuously changed (e.g., in a global standard block, local elements varied trial-by-trial). MMN was found only for global deviant patterns, and only when deviation occurred late in the pattern. In a separate behavioral experiment, global deviants were detected more often than local ones, although initial similarity followed by a late deviation from the standard pattern was not required for explicit deviant detection (as with the MMN). This report demonstrates neural structural encoding for global information, when independently manipulated from local information. Furthermore, it extends previous MMN findings that have revealed indexing of complex abstract auditory information to the realm of hierarchical perceptual organization.