Word inversion sensitivity as a marker of visual word form area lateralization: An application of a novel multivariate measure of laterality

Preschool Children with High Reading Ability Show Inversion Sensitivity to Words in Environment: An Eye-Tracking Study

Words in environmental print are exposed to young children before formally learning to read, and attention to these words is linked to their reading ability. Inversion sensitivity, the ability to distinguish between upright and inverted words, is a pivotal milestone in reading development. To further explore the relationship between attention to words in environmental print and early reading development, we examined whether children with varying reading abilities differed in inversion sensitivity to these words. Participants included children with low (18, 8 males, 5.06 years) and high (19, 10 males, 5.00 years) reading levels. Using an eye-tracking technique, we compared children's attention to upright and inverted words in environmental print and ordinary words during a free-viewing task. In terms of the percentage of fixation duration and fixation count, results showed that children with high reading abilities exhibited inversion sensitivity to words in environmental print, whereas children with low reading abilities did not. Unexpectedly, in terms of first fixation latency, children with low reading abilities showed inversion sensitivity to ordinary words, while children with high reading abilities did not. These findings suggest that inversion sensitivity to words in environmental print is closely linked to early reading ability.

Functional and representational differences between bilateral inferior temporal numeral areas

The processing of numerals as visual objects is supported by an "Inferior Temporal Numeral Area" (ITNA) in the bilateral inferior temporal gyri (ITG). Extant findings suggest some degree of hemispheric asymmetry in how the bilateral ITNAs process numerals. Pollack and Price (2019) reported such a hemispheric asymmetry by which a region in the left ITG was sensitive to digits during a visual search for a digit among letters, and a homologous region in the right ITG that showed greater digit sensitivity in individuals with higher calculation skills. However, the ITG regions were localized with separate analyses without directly contrasting their digit sensitivities and relation to calculation skills. So, the extent of and reasons for these functional asymmetries remain unclear. Here we probe whether the functional and representational properties of the ITNAs are asymmetric by applying both univariate and multivariate region-of-interest analyses to Pollack and Price's (2019) data. Contrary to the implications of the original findings, digit sensitivity did not differ between ITNAs, and digit sensitivity in both left and right ITNAs was associated with calculation skills. Representational similarity analyses revealed that the overall representational geometries of digits in the ITNAs were also correlated, albeit weakly, but the representational contents of the ITNAs were largely inconclusive. Nonetheless, we found a right lateralization in engagement in alphanumeric categorization, and that the right ITNA showed greater discriminability between digits and letters. Greater right lateralization of digit sensitivity and digit discriminability in the left ITNA were also related to higher calculation skills. Our findings thus suggest that the ITNAs may not be functionally identical and should be directly contrasted in future work. Our study also highlights the importance of within-individual comparisons for understanding hemispheric asymmetries, and analyses of individual differences and multivariate features to uncover effects that would otherwise be obscured by averages.

Action-rule-based cognitive control enables efficient execution of stimulus-response conflict tasks: a model validation of Simon task performance

Introduction

The human brain can flexibly modify behavioral rules to optimize task performance (speed and accuracy) by minimizing cognitive load. To show this flexibility, we propose an action-rule-based cognitive control (ARC) model. The ARC model was based on a stochastic framework consistent with an active inference of the free energy principle, combined with schematic brain network systems regulated by the dorsal anterior cingulate cortex (dACC), to develop several hypotheses for demonstrating the validity of the ARC model.

Methods

A step-motion Simon task was developed involving congruence or incongruence between important symbolic information (illustration of a foot labeled "L" or "R," where "L" requests left and "R" requests right foot movement) and irrelevant spatial information (whether the illustration is actually of a left or right foot). We made predictions for behavioral and brain responses to testify to the theoretical predictions.

Results

Task responses combined with event-related deep-brain activity (ER-DBA) measures demonstrated a key contribution of the dACC in this process and provided evidence for the main prediction that the dACC could reduce the Shannon surprise term in the free energy formula by internally reversing the irrelevant rapid anticipatory postural adaptation. We also found sequential effects with modulated dip depths of ER-DBA waveforms that support the prediction that repeated stimuli with the same congruency can promote remodeling of the internal model through the information gain term while counterbalancing the surprise term.

Discussion

Overall, our results were consistent with experimental predictions, which may support the validity of the ARC model. The sequential effect accompanied by dip modulation of ER-DBA waveforms suggests that cognitive cost is saved while maintaining cognitive performance in accordance with the framework of the ARC based on 1-bit congruency-dependent selective control.

Novel approaches to functional lateralization: Assessing information in activity patterns across hemispheres and more accurately identifying structural homologues

Functional lateralization is typically measured by comparing activation levels across the right and left hemispheres of the brain. Significant additional information, however, exists within distributed multi-voxel patterns of activity - a format not detectable by traditional activation-based analysis of functional magnetic resonance imaging (fMRI) data. We introduce and test two methods -one anatomical, one functional- that allow hemispheric information asymmetries to be detected. We first introduce and apply a novel tool that draws on brain 'surface fingerprints' to pair every location in one hemisphere with its hemispheric homologue. We use anatomical data to show that this approach is more accurate than the common distance-from-midline method for comparing bilateral regions. Next, we introduce a complementary analysis method that quantifies multivariate laterality in functional data. This new 'multivariate Laterality Index' (mLI) reflects both quantitative and qualitative information-differences across homologous activity patterns. We apply the technique here to functional data collected as participants viewed faces and non-faces. Using the previously generated surface fingerprints to pair-up homologous searchlights in each hemisphere, we use the novel multivariate laterality technique to identify face-information asymmetries across right and left counterparts of the fusiform gyrus, inferior temporal gyrus, superior parietal lobule, and early visual areas. The typical location of the fusiform face area has greater information asymmetry for faces than for shapes. More generally, we argue that the field should consider an information-based approach to lateralization.

Change detection versus change localization for faces, houses, and words

Holistic processing aids in the discrimination of visually similar objects, but it may also come with a cost. Indeed holistic processing may improve the ability to detect changes to a face while impairing the ability to locate where the changes occur. We investigated the capacity to detect the occurrence of a change versus the capacity to detect the localization of a change for faces, houses, and words. Change detection was better than change localization for faces. Change localization outperformed change detection for houses. For words, there was no difference between detection and localization. We know from previous studies that words are processed holistically. However, being an object of visual expertise processed holistically, visual words are also a linguistic entity. Previously, the word composite effect was found for phonologically consistent words but not for phonologically inconsistent words. Being an object of visual expertise for which linguistic information is important, letter position information, is also crucial. Thus, the importance of localization of letters and features may augment the capacity to localize a change in words making the detection of a change and the detection of localization of a change equivalent.

Beyond the Visual Word Form Area - a cognitive characterization of the left ventral occipitotemporal cortex

The left ventral occipitotemporal cortex has been traditionally viewed as a pathway for visual object recognition including written letters and words. Its crucial role in reading was strengthened by the studies on the functionally localized "Visual Word Form Area" responsible for processing word-like information. However, in the past 20 years, empirical studies have challenged the assumptions of this brain region as processing exclusively visual or even orthographic stimuli. In this review, we aimed to present the development of understanding of the left ventral occipitotemporal cortex from the visually based letter area to the modality-independent symbolic language related region. We discuss theoretical and empirical research that includes orthographic, phonological, and semantic properties of language. Existing results showed that involvement of the left ventral occipitotemporal cortex is not limited to unimodal activity but also includes multimodal processes. The idea of the integrative nature of this region is supported by the broad functional and structural connectivity with language-related and attentional brain networks. We conclude that although the function of the area is not yet fully understood in human cognition, its role goes beyond visual word form processing. The left ventral occipitotemporal cortex seems to be crucial for combining higher-level language information with abstract forms that convey meaning independently of modality.

Developmental emergence of holistic processing in word recognition

Holistic processing (HP) of faces refers to the obligatory, simultaneous processing of the parts and their relations, and it emerges over the course of development. HP is manifest in a decrement in the perception of inverted versus upright faces and a reduction in face processing ability when the relations between parts are perturbed. Here, adopting the HP framework for faces, we examined the developmental emergence of HP in another domain for which human adults have expertise, namely, visual word processing. Children, adolescents, and adults performed a lexical decision task and we used two established signatures of HP for faces: the advantage in perception of upright over inverted words and nonwords and the reduced sensitivity to increasing parts (word length). Relative to the other groups, children showed less of an advantage for upright versus inverted trials and lexical decision was more affected by increasing word length. Performance on these HP indices was strongly associated with age and with reading proficiency. Also, the emergence of HP for word perception was not simply a result of improved visual perception over the course of development as no group differences were observed on an object decision task. These results reveal the developmental emergence of HP for orthographic input, and reflect a further instance of experience-dependent tuning of visual perception. These results also add to existing findings on the commonalities of mechanisms of word and face recognition. RESEARCH HIGHLIGHTS: Children showed less of an advantage for upright versus inverted trials compared to adolescents and adults. Relative to the other groups, lexical decision in children was more affected by increasing word length. Performance on holistic processing (HP) indices was strongly associated with age and with reading proficiency. HP emergence for word perception was not due to improved visual perception over development as there were no group differences on an object decision task.

Category-specific and category-general neural codes of recognition memory in the ventral visual pathway

Researchers have identified category-specific brain regions, such as the fusiform face area (FFA) and parahippocampal place area (PPA) in the ventral visual pathway, which respond preferentially to one particular category of visual objects. In addition to their category-specific role in visual object identification and categorization, regions in the ventral visual pathway play critical roles in recognition memory. Nevertheless, it is not clear whether the contributions of those brain regions to recognition memory are category-specific or category-general. To address this question, the present study adopted a subsequent memory paradigm and multivariate pattern analysis (MVPA) to explore category-specific and category-general neural codes of recognition memory in the visual pathway. The results revealed that the right FFA and the bilateral PPA showed category-specific neural patterns supporting recognition memory of faces and scenes, respectively. In contrast, the lateral occipital cortex seemed to carry category-general neural codes of recognition memory. These results provide neuroimaging evidence for category-specific and category-general neural mechanisms of recognition memory in the ventral visual pathway.

The depth of semantic processing modulates cross-language pattern similarity in Chinese-English bilinguals

Previous studies have investigated factors related to the degree of cross-language overlap in brain activations in bilinguals/multilinguals. However, it is still unclear whether and how the depth of semantic processing (a critical task-related factor) affects the neural pattern similarity between native and second languages. To address this question, 26 Chinese-English bilinguals were scanned with fMRI while performing a word naming task (i.e., a task with shallow semantic processing) and a semantic judgment task (i.e., a task with deep semantic processing) in both native and second languages. Based on three sets of representational similarity analysis (whole brain, ROI-based, and within-language vs. cross-language semantic representation), we found that select regions in the reading brain network showed higher cross-language pattern similarity and higher cross-language semantic representations during deep semantic processing than during shallow semantic processing. These results suggest that compared to shallow semantic processing, deep semantic processing may lead to greater language-independent processing (i.e., cross-language semantic representation) and cross-language pattern similarity, and provide direct quantitative neuroimaging evidence for cognitive models of bilingual lexical memory.

Culture is not destiny, for reading: highlighting variable routes to literacy within writing systems

Cross-writing system research in psychology and cognitive neuroscience has yielded important findings regarding how a writing system's structure can influence the cognitive challenges of learning to read and the neural underpinnings of literacy. The current paper reviews these differences and extends the findings to demonstrate diversity in how skilled reading is accomplished within a single writing system, English. We argue that broad clusters of behavioral and neural patterns found across writing systems can also be found within subpopulations who display atypical routes to skilled English reading, subpopulations including Chinese-English bilinguals, deaf native signers, compensated readers, and distortion-sensitive readers. The patterns of interest include a tradeoff between the degree of reliance on phonological and morphological processing for skilled reading, a shift in attentional focus from smaller to larger orthographic units, and enhanced bilaterality of neural processing during word reading. Lastly, we consider how understanding atypical routes to reading may apply to other writing systems.

The effects of stimulus inversion on the neural representations of Chinese character and face recognition

This study investigates whether stimulus inversion influences neural responses of Chinese character recognition similarly to its effect on face recognition in category-selective and object-related brain areas using functional magnetic resonance imaging. Participants performed a one-back matching task for simple (one radical) and compound (two radicals) Chinese characters and faces with upright and inverted orientations. Inverted stimuli produced slower response times with stronger activity within the fusiform gyrus (FG) than upright stimuli for faces and Chinese characters. While common inversion-related activation was identified in the left FG among stimulus types, we observed a significant inter-regional correlation between the left FG and the intraparietal sulcus for face inversion. Importantly, analyses of region-of-interest (ROI) multivariate pattern classification showed that classifiers trained on face inversion can decode the representations of character inversion in the character-selective ROI. However, this was not true for face inversion in face-selective ROIs when the classifiers were trained on characters. Similar activity patterns for character and face inversion were observed in the object-related ROIs. We also showed higher decoding accuracy for upright stimuli in the face-selective ROI than in the character-selective ROI but this was not true for inverted ones or when patterns were examined in the object-related ROIs. Together, our results support shared and distinct configural representations for character and face recognition in category-selective and object-related brain areas.

Neural Representation in Visual Word Form Area during Word Reading

The visual word form area (VWFA) has been consistently identified as a crucial structure in visual word processing. Nevertheless, it is controversial whether the VWFA represents external visual information (e.g., case information) of visual words. To address that question, we functionally localized VWFA at the group level (gVWFA) and at the individual level (iVWFA), and used multivariate pattern analysis (MVPA) to explore the information representation in the VWFA during an implicit reading task (i.e., a passive viewing task). Univariate activation analysis revealed that participants showed stronger activations for uppercase English words compared to lowercase ones in the VWFA. MVPA further revealed that the classifier trained based on lowercase words versus letter strings significantly distinguished uppercase words versus letter strings in the iVWFA, while that trained based on lowercase words versus uppercase words distinguished lowercase letter strings versus uppercase letter strings neither in the gVWFA nor in the iVWFA. These results suggest that the VWFA does not represent case information, but represents case-independent linguistic information. Our findings elaborate the function in the VWFA and support the VWFA hypothesis.

The Trajectory of Hemispheric Lateralization in the Core System of Face Processing: A Cross-Sectional Functional Magnetic Resonance Imaging Pilot Study

Face processing is mediated by a distributed neural network commonly divided into a “core system” and an “extended system.” The core system consists of several, typically right-lateralized brain regions in the occipito-temporal cortex, including the occipital face area (OFA), the fusiform face area (FFA) and the posterior superior temporal sulcus (pSTS). It was recently proposed that the face processing network is initially bilateral and becomes right-specialized in the course of the development of reading abilities due to the competition between language-related regions in the left occipito-temporal cortex (e.g., the visual word form area, VWFA) and the FFA for common neural resources. In the present pilot study, we assessed the neural face processing network in 12 children (aged 7–9 years) and 10 adults with functional magnetic resonance imaging (fMRI). The hemispheric lateralization of the core face regions was compared between both groups. The study had two goals: First, we aimed to establish an fMRI paradigm suitable for assessing activation in the core system of face processing in young children at the single subject level. Second, we planned to collect data for a power analysis to calculate the necessary group size for a large-scale cross-sectional imaging study assessing the ontogenetic development of the lateralization of the face processing network, with focus on the FFA. It was possible to detect brain activity in the core system of 75% of children at the single subject level. The average scan-to-scan motion of the included children was comparable to adults, ruling out that potential activation differences between groups are caused by unequal motion artifacts. Hemispheric lateralization of the FFA was 0.07 ± 0.48 in children (indicating bilateral activation) and −0.32 ± 0.52 in adults (indicating right-hemispheric dominance). These results thus showed, as expected, a trend for increased lateralization in adults. The estimated effect size for the FFA lateralization difference was d = 0.78 (indicating medium to large effects). An adequately powered follow-up study (sensitivity 0.8) testing developmental changes of FFA lateralization would therefore require the inclusion of 18 children and 26 adults.

Neural pattern similarity across concept exemplars predicts memory after a long delay

The irregularities of the world ensure that each interaction we have with a concept is unique. In order to generalize across these unique encounters to form a high-level representation of a concept, we must draw on similarities between exemplars to form new conceptual knowledge that is maintained over a long time. Two neural similarity measures - pattern robustness and encoding-retrieval similarity - are particularly important for predicting memory outcomes. In this study, we used fMRI to measure activity patterns while people encoded and retrieved novel pairings between unfamiliar (Dutch) words and visually presented animal species. We address two underexplored questions: 1) whether neural similarity measures can predict memory outcomes, despite perceptual variability between presentations of a concept and 2) if pattern similarity measures can predict subsequent memory over a long delay (i.e., one month). Our findings indicate that pattern robustness during encoding in brain regions that include parietal and medial temporal areas is an important predictor of subsequent memory. In addition, we found significant encoding-retrieval similarity in the left ventrolateral prefrontal cortex after a month's delay. These findings demonstrate that pattern similarity is an important predictor of memory for novel word-animal pairings even when the concept includes multiple exemplars. Importantly, we show that established predictive relationships between pattern similarity and subsequent memory do not require visually identical stimuli (i.e., are not simply due to low-level visual overlap between stimulus presentations) and are maintained over a month.

The Battle between the Correct and Mirror Writings of a Digit in Children’s Recognition Memory

Recent research into character reversals in writings produced by occidental children has shown that they mainly reverse the left-oriented digits (1, 2, 3, 7, and 9) and therefore appear to apply a right-orienting rule. But do they produce similar reversal errors when asked to recognize the digits? In an experiment, based on eye-tracking observations of 50 children (Mage = 5.4 years), children had to point towards a target digit in a 2 × 2 matrix also containing three distractor digits, one of which was the mirror-reversed writing of the correctly written target digit. This recognition task led to a true “battle” in children’s memory between the two writings of the target digit. This battle is shown in the graphical abstract that represents a heat map from a sub-sample of children (on the left side) and the fixation points map from an individual child (on the right side). Rather than following the predicted right-orienting rule, the children’s responses appeared to be biased towards digits in the right-hand column of the 2 × 2 matrices (when the reversed target digit was not in the same column as the correctly written target digit). As a whole, these findings support the hypotheses that many 4- to 6-year-old’s representations of the digit writings are unoriented in their memory and that these children may adopt different solutions to overcome this lack of orientation depending on whether they write or read.

Unmasking individual differences in adult reading procedures by disrupting holistic orthographic perception

Word identification is undeniably important for skilled reading and ultimately reading comprehension. Interestingly, both lexical and sublexical procedures can support word identification. Recent cross-linguistic comparisons have demonstrated that there are biases in orthographic coding (e.g., holistic vs. analytic) linked with differences in writing systems, such that holistic orthographic coding is correlated with lexical-level reading procedures and vice versa. The current study uses a measure of holistic visual processing used in the face processing literature, orientation sensitivity, to test individual differences in word identification within a native English population. Results revealed that greater orientation sensitivity (i.e., greater holistic processing) was associated with a reading profile that relies less on sublexical phonological measures and more on lexical-level characteristics within the skilled English readers. Parallels to Chinese procedures of reading and a proposed alternative route to skilled reading are discussed.

A compositional neural code in high-level visual cortex can explain jumbled word reading

We read jubmled wrods effortlessly, but the neural correlates of this remarkable ability remain poorly understood. We hypothesized that viewing a jumbled word activates a visual representation that is compared to known words. To test this hypothesis, we devised a purely visual model in which neurons tuned to letter shape respond to longer strings in a compositional manner by linearly summing letter responses. We found that dissimilarities between letter strings in this model can explain human performance on visual search, and responses to jumbled words in word reading tasks. Brain imaging revealed that viewing a string activates this letter-based code in the lateral occipital (LO) region and that subsequent comparisons to stored words are consistent with activations of the visual word form area (VWFA). Thus, a compositional neural code potentially contributes to efficient reading.

Hemispheric Organization for Visual Object Recognition: A Theoretical Account and Empirical Evidence

Despite the similarity in structure, the hemispheres of the human brain have somewhat different functions. A traditional view of hemispheric organization asserts that there are independent and largely lateralized domain-specific regions in ventral occipitotemporal (VOTC), specialized for the recognition of distinct classes of objects. Here, we offer an alternative account of the organization of the hemispheres, with a specific focus on face and word recognition. This alternative account relies on three computational principles: distributed representations and knowledge, cooperation and competition between representations, and topography and proximity. The crux is that visual recognition results from a network of regions with graded functional specialization that is distributed across both hemispheres. Specifically, the claim is that face recognition, which is acquired relatively early in life, is processed by VOTC regions in both hemispheres. Once literacy is acquired, word recognition, which is co-lateralized with language areas, primarily engages the left VOTC and, consequently, face recognition is primarily, albeit not exclusively, mediated by the right VOTC. We review psychological and neural evidence from a range of studies conducted with normal and brain-damaged adults and children and consider findings which challenge this account. Last, we offer suggestions for future investigations whose findings may further refine this account.

Holistic word processing is correlated with efficiency in visual word recognition

Holistic processing of visual words (i.e., obligatory encoding of/attending to all letters of a word) could be a marker of expert word recognition. In the present study, we thus examined for the first time whether there is a direct relation between the word-composite effect (i.e., all parts of a visual word are fully processed when observers perform a task on a word part) and fast access to the orthographic lexicon by visual word experts (i.e., fluent adult readers). We adopted an individual differences approach and used the word-frequency effect (i.e., faster recognition of high- than low-frequency words) in an independent lexical decision task as a proxy of fast access to lexical orthographic representations. Fluent readers with larger word-composite effect showed smaller word-frequency effect. This correlation was mainly driven by an association between a larger composite effect and faster lexical decision on low-frequency words, probably because these lexical representations are less stable and integrated/unitized, hence allowing differentiating among fluent readers. We thus showed that holistic processing of visual words is indeed related to higher efficiency in visual word recognition by skilled readers.

Decoding spatial location of perceived pain to acupuncture needle using multivoxel pattern analysis

The present study applied multivoxel pattern analysis to decode spatial discrimination in pain perception to acupuncture needle from brain functional magnetic resonance image. Fourteen participants were stimulated by acupuncture needles at two adjacent body parts on their left forearm (PC6 vs. HT7). We trained support vector machines on the spatial information from the whole-brain functional magnetic resonance imaging data and projected the support vector machine weight to the brain image space to represent the effect of each voxel on the classifier output. Using region-of-interest masks in individual brains, we trained and tested a linear support vector machine classifier on the accuracy of spatial discrimination in trial-wise functional magnetic resonance imaging data. A classical univariate general linear model analysis testing for differences between the two different locations did not reveal any significant differences. Multivoxel pattern analysis revealed that the brain regions for the prediction of sensory discrimination in pain perceptions to two different points were in the primary somatosensory cortex, primary motor cortex, and supramarginal gyrus, anterior and posterior insula, anterior and posterior cingulate cortex, ventromedial prefrontal cortex, and inferior parietal lobule. Our findings suggest that spatial localizations of pain perceptions to acupuncture needle can be predicted by the neural response patterns in the somatosensory areas and the frontoparietal areas.

Holistic word context does not influence holistic processing of artificial objects in an interleaved composite task

Holistic processing, a hallmark of expert processing, has been shown for written words, signaled by the word composite effect, similar to the face composite effect: fluent readers find it difficult to focus on just one half of a written word while ignoring the other half, especially when the two word halves are aligned rather than misaligned. This effect is signaled by a significant interaction between alignment and congruency of the two word parts. Face and visual word recognition, however, involve different neural mechanisms with an opposite hemispheric lateralization. It is then possible that faces and words can both involve holistic processing in their own separate face and word processing systems, but by using different mechanisms. In the present study, we replicated with words a previous study done with faces (Richler, Bukach, & Gauthier, 2009, Experiment 3). In a first experiment we showed that in a composite task with aligned artificial objects, no congruency effects are found. In a second experiment, using an interleaved task, a congruency effect for Ziggerins was induced in trials in which a word was first encoded, but more strongly when it was aligned. However, in a stricter test, we found no differences between the congruency effect for Ziggerins induced by aligned words versus pseudowords. Our results demonstrate that different mechanisms can underlie holistic processing in different expertise domains.