The neural signature of numerosity by separating numerical and continuous magnitude extraction in visual cortex with frequency-tagged EEG.

The ability to handle approximate quantities, or number sense, has been recurrently linked to mathematical skills, although the nature of the mechanism allowing to extract numerical information (i.e., numerosity) from environmental stimuli is still debated. A set of objects is indeed not only characterized by its numerosity but also by other features, such as the summed area occupied by the elements, which often covary with numerosity. These intrinsic relations between numerosity and nonnumerical magnitudes led some authors to argue that numerosity is not independently processed but extracted through a weighting of continuous magnitudes. This view cannot be properly tested through classic behavioral and neuroimaging approaches due to these intrinsic correlations. The current study used a frequency-tagging EEG approach to separately measure responses to numerosity as well as to continuous magnitudes. We recorded occipital responses to numerosity, total area, and convex hull changes but not to density and dot size. We additionally applied a model predicting primary visual cortex responses to the set of stimuli. The model output was closely aligned with our electrophysiological data, since it predicted discrimination only for numerosity, total area, and convex hull. Our findings thus demonstrate that numerosity can be independently processed at an early stage in the visual cortex, even when completely isolated from other magnitude changes. The similar implicit discrimination for numerosity as for some continuous magnitudes, which correspond to basic visual percepts, shows that both can be extracted independently, hence substantiating the nature of numerosity as a primary feature of the visual scene.

The extraction of orthographic and phonological structure of printed words in adults with dyslexia.

The current study investigated the extraction of orthographic and phonological structure of written words in adults with dyslexia. In adults without learning difficulties, Chetail and Content showed that orthographic structure, as determined by the number of vowel letter clusters, influences visual word length estimation. The authors also found a phonological effect determined by the number of syllables of words. In the present study, 22 French-speaking students diagnosed with dyslexia in childhood and 22 students without learning disabilities were compared. All participants performed the task of estimating word length. The pattern of results obtained by Chetail and Content was replicated: length estimates were biased by both the number of syllables and the number of vowel letter clusters. The study showed a significant interaction between phonological bias and group. The phonological effect was less important in students with dyslexia, suggesting reduced sensitivity to phonological parsing in reading. In contrast, the orthographic effect did not differ significantly between groups, suggesting that the sensitivity to the orthographic structure of written words is preserved in students with dyslexia despite their low-quality orthographic representations. We conclude that there is no systematic association between sensitivity to the structure of representations and quality of their content.

Approximate number sense theory or approximate theory of magnitude?

Leibovich et al. argue that the evidence in favor of a perceptual mechanism devoted to the extraction of numerosity from visual collections is unsatisfactory and propose to replace it with an unspecific mechanism capturing approximate magnitudes from continuous dimensions. We argue that their representation of the evidence is incomplete and that their theoretical proposal is too vague to be useful.

BACS: The Brussels Artificial Character Sets for studies in cognitive psychology and neuroscience.

Written symbols such as letters have been used extensively in cognitive psychology, whether to understand their contributions to written word recognition or to examine the processes involved in other mental functions. Sometimes, however, researchers want to manipulate letters while removing their associated characteristics. A powerful solution to do so is to use new characters, devised to be highly similar to letters, but without the associated sound or name. Given the growing use of artificial characters in experimental paradigms, the aim of the present study was to make available the Brussels Artificial Character Sets (BACS): two full, strictly controlled, and portable sets of artificial characters for a broad range of experimental situations.

Assessing the Approximate Number System: no relation between numerical comparison and estimation tasks.

Whether our general numerical skills and the mathematical knowledge that we acquire at school are entwined is a debated issue, which many researchers are still striving to investigate. The findings reported in the literature are actually inconsistent; some studies emphasized the existence of a relationship between the acuity of the Approximate Number System (ANS) and arithmetic competence, while some others did not observe any significant correlation. One potential explanation of the discrepancy might stem from the evaluation of the ANS itself. In the present study, we correlated two measures used to index ANS acuity with arithmetic performance. These measures were the Weber fraction (w), computed from a numerical comparison task and the coefficient of variation (CV), computed from a numerical estimation task. Arithmetic performance correlated with estimation CV but not with comparison w. We further investigated the meaning of this result by taking the relationship between w and CV into account. We expected a tight relation as both these measures are believed to assess ANS acuity. Crucially, however, w and CV did not correlate with each other. Moreover, the value of w was modulated by the congruity of the relation between numerical magnitude and non-numerical visual cues, potentially accounting for the lack of correlation between the measures. Our findings thus challenge the overuse of w to assess ANS acuity and more generally put into question the relevance of correlating this measure with arithmetic without any deeper understanding of what they are really indexing.

What is the difference between OASIS and OPERA? Roughly five pixels: orthographic structure biases the perceived length of letter strings.

A thorough understanding of monosyllabic-word-recognition processes, in contrast with multisyllabic-word processing, has accumulated over the past decades. One fundamental challenge regarding multisyllabic words concerns their parsing into smaller units and the nature of the cues determining the parsing. We propose that the organization of consonant and vowel letters provides powerful cues for parsing, and we present data from a new task showing that a word's orthographic structure, as determined by the number of vowel-letter clusters, influences estimations of its length. Words were briefly presented on a computer screen, and participants had to estimate word length by drawing a line on the screen with the mouse. In three experiments, participants estimated words comprising fewer orthographic units as shorter than words comprising more units even though the words matched for number of letters. Further results demonstrated that the length bias was driven by orthographic information and not by phonological structure.

Segmentation of written words in French.

Syllabification of spoken words has been largely used to define syllabic properties of written words, such as the number of syllables or syllabic boundaries. By contrast, some authors proposed that the functional structure of written words stems from visuo-orthographic features rather than from the transposition of phonological structure into the written modality. Thus, the first aim of the study was to assess whether the explicit segmentation of written words in French was consistent with syllabification patterns for spoken words previously reported. Second, given that spelling does not map perfectly with phonology, we examined how readers segmented printed words with grapheme/phoneme misalignments. The examination of the whole patterns of written segmentation produced by participants showed that, though written segmentation followed spoken segmentation for words matched for phonological/orthographic forms, discrepancies were found in cases of mismatch, therefore suggesting that readers rely on orthographic cues to parse printed strings of letters. This conclusion was confirmed with an on-line letter detection task.

Attentional engagement in letter-like shape learning.

Recent studies suggest that letter representations are based on a multimodal network linking the graphic motor programs acquired through handwriting to the visual representations. Moreover, the graphic motor programs are assumed to contribute to letter recognition. This assumption is based on the finding that learning symbols through handwriting leads to better recognition than learning through typing. However, in addition to the type of motor activity engaged, handwriting and typing might also differ in other aspects. Indeed, handwriting requires a more detailed visual analysis of the target symbols, which may account for its learning advantage (Seyll et al., 2020). Moreover, different learning methods might differ in attentional engagement. The present study aimed at measuring and comparing the attentional demands incurred by different learning settings. To this purpose, a dual-task probe paradigm was used: participants had to respond as quickly as possible to auditory probes while learning symbols either through handwriting, typing, or composition-a method requiring detailed visual analysis without graphomotor activity. Reaction times to the probes were used as index of the attentional engagement required by the learning methods. Handwriting led to longer reaction times than typing and composition, suggesting that it requires more attention than both other learning methods. Thus, the recognition advantage of handwriting over typing might be partly attributable to attentional engagement during learning. In addition, the advantage of composition over typing, in the absence of differences in the attentional task, confirms the unique importance of detailed visual analysis in symbol memorization. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The nature of perceptual units in Chinese character recognition.

Chinese character recognition is based on a limited set of recurrent stroke patterns. Most Chinese characters are a combination of two or more of these components. To test whether readers are sensitive to combinations of components (or multi-component units [MCUs]) within a character, we conducted two probe detection tasks where participants had to detect the presence of a component in a target character. Critically, some targets contained an MCU that can stand as a character on its own, with its own meaning and sound, while other targets contained an MCU that only exists embedded within other characters (no associated meaning and sound). Participants had more difficulty detecting component probes that were a part of an existing MCU, compared to component probes that belonged to a non-existing MCU. These findings suggest that existing MCUs are a perceptual unit in Chinese character recognition.

Letter-Like Shape Recognition in Preschool Children: Does Graphomotor Knowledge Contribute?

Based on evidence that learning new characters through handwriting leads to better recognition than learning through typing, some authors proposed that the graphic motor plans acquired through handwriting contribute to recognition. More recently two alternative explanations have been put forward. First, the advantage of handwriting could be due to the perceptual variability that it provides during learning. Second, a recent study suggests that detailed visual analysis might be the source of the advantage of handwriting over typing. Indeed, in that study, handwriting and composition -a method requiring a detailed visual analysis but no specific graphomotor activity- led to equivalent recognition accuracy, both higher than typing. The aim of the present study was to assess whether the contribution of detailed visual analysis is observed in preschool children and to test the variability hypothesis. To that purpose, three groups of preschool children learned new symbols either by handwriting, typing, or composition. After learning, children performed first a four-alternative recognition task and then a categorization task. The same pattern of results as the one observed in adults emerged in the four-alternative recognition task, confirming the importance of the detailed visual analysis in letter-like shape learning. In addition, results failed to reveal any difference across learning methods in the categorization task. The latter results provide no evidence for the variability hypothesis which would predict better categorization after handwriting than after typing or composition.

The interaction between numerical and continuous non-numerical magnitudes in a double change detection paradigm.

In the field of numerical cognition, researchers conventionally assess nonsymbolic numerical abilities with the help of number comparison tasks, in which participants need to compare two arrays. Many studies emphasized that visual (non-numerical) dimensions can serve as strategic cues and influence the decision on numerosity in these tasks. In this study, we suggest the use of a novel paradigm based on the change detection paradigm. Here, participants had to simultaneously pay attention to numerical changes and visual changes on a target non-numerical dimension (individual area, total area, field area, or density). Participants had to detect changes relative to the two dimensions and press response keys indicating either number change or visual change or press both keys. In such a double change detection paradigm, and unlike number comparison tasks, target and covarying dimensions cannot serve as cues to influence the numerical decision. We found that numerical change detection was excellent and stable across the conditions. Further, participants were more likely to falsely consider visual changes as numerical changes than the other way around. Lastly, when both dimensions varied, participants more frequently missed visual changes than numerical changes. Overall, our findings show that numerosity was the most salient visual dimension. From a methodological perspective, such a double change detection paradigm could be of critical interest to assess numerical abilities for future studies. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Mutual influences between numerical and non-numerical quantities in comparison tasks.

Humans possess a numerical intuition that allows them to manipulate large non-symbolic quantities. This ability has been broadly assessed with the help of number comparison tasks involving simultaneously displayed arrays. Many authors pointed out that the manipulation (or the lack thereof) of non-numerical features deeply impacts performance in these tasks, but the specific nature of this influence is not clear. This study investigates the interaction between numerical and non-numerical quantity judgement tasks. Adult participants performed five distinct comparison tasks, each based on a target dimension: numerosity, total area, dot size, convex hull, and mean occupancy. We manipulated the relation between the target and the other dimensions to measure their respective influence on task performance. Results showed that total area and convex hull substantially affected numerosity comparisons. The number of dots conversely acted as an informative dimension when participants had to make a decision based on the total area or the convex hull. Our results illustrate that adults flexibly use non-target dimensions as visual cues to perform comparison judgements. Overall, this suggests that the influence found in numerical comparison tasks is explicit and deliberate rather than due to implicit visual integration processes.

Automatic Processing of Numerosity in Human Neocortex Evidenced by Occipital and Parietal Neuromagnetic Responses.

Humans and other animal species are endowed with the ability to sense, represent, and mentally manipulate the number of items in a set without needing to count them. One central hypothesis is that this ability relies on an automated functional system dedicated to numerosity, the perception of the discrete numerical magnitude of a set of items. This system has classically been associated with intraparietal regions, however accumulating evidence in favor of an early visual number sense calls into question the functional role of parietal regions in numerosity processing. Targeting specifically numerosity among other visual features in the earliest stages of processing requires high temporal and spatial resolution. We used frequency-tagged magnetoencephalography to investigate the early automatic processing of numerical magnitudes and measured the steady-state brain responses specifically evoked by numerical and other visual changes in the visual scene. The neuromagnetic responses showed implicit discrimination of numerosity, total occupied area, and convex hull. The source reconstruction corresponding to the implicit discrimination responses showed common and separate sources along the ventral and dorsal visual pathways. Occipital sources attested the perceptual salience of numerosity similarly to both other implicitly discriminable visual features. Crucially, we found parietal responses uniquely associated with numerosity discrimination, showing automatic processing of numerosity in the parietal cortex, even when not relevant to the task. Taken together, these results provide further insights into the functional roles of parietal and occipital regions in numerosity encoding along the visual hierarchy.

Early Sensitivity to Morphology in Beginning Readers of Arabic.

The current study investigated the influence of morphological structure on the earliest stages of Arabic reading acquisition. More specifically, we aimed at examining the role of root and pattern units in beginners from Grade 1 to 3. A first set of reading tasks evaluated the presence of a morphology facilitation effect in word and pseudoword reading by manipulating independently the frequency of roots and patterns. Additional tasks aimed at examining the contribution of morphological awareness to reading performance. The results suggest that reading ability is early influenced by the awareness of morphological composition. Children read faster and more accurately pseudowords composed of frequent morphemes. Furthermore, regression analyses revealed, for every reading measure, a significant contribution of one morphological test in addition to grapheme knowledge. Results are discussed taking into account the differences obtained depending on lexicality and morpheme type (root or pattern).

The impact of graphomotor demands on letter-like shapes recognition: A comparison between hampered and normal handwriting.

Recent research suggests that graphic motor programs acquired through writing are part of letter representations and contribute to their recognition. Indeed, learning new letter-like shapes through handwriting gave rise to better recognition than learning through methods suppressing the graphomotor activity (e.g., typing or viewing). The present study aimed at further assessing the role of the graphic motor programs in letter-like shape recognition by disturbing the graphomotor activity during learning. We compared recognition performance following normal handwriting to recognition performance following hampered handwriting. Adult participants learned sets of symbols by copying them either with a standard pen or with a hampering writing tool. Recognition tests were administered immediately after the learning phase and again one week later. The results revealed lower recognition accuracy following hampered handwriting than following normal handwriting suggesting a contribution of graphomotor skills in the construction of letter representation.

The impact of graphic motor programs and detailed visual analysis on letter-like shape recognition.

Recent research suggests that graphic motor programs acquired through writing are part of letter representations and contribute to their recognition. Indeed, learning new letter-like shapes through handwriting gave rise to better recognition than learning through typing on a keyboard. However, handwriting and typing do not differ solely by the nature of the motor activity. Handwriting requires a detailed visual analysis in order to reproduce all elements of the target shape. In contrast, typing relies on visual discrimination between graphic forms and does not require such detailed processing. The aim of the present study was to disentangle the respective contribution of visual analysis and graphomotor knowledge. We compared handwriting and typing to learning by composition, a new method which requires a detailed visual analysis of the target without the specific graphomotor activity. Participants composed the target symbols by selecting elementary features from the set displayed on the screen and dragging them in the appropriate position. In four experiments, adult participants learned sets of symbols through handwriting, typing or composition. Recognition tests were administered immediately after the learning phase and again two to three weeks later. Taken together, the results of the four experiments confirm the importance of the detailed visual analysis and provide no evidence for an influence of motor knowledge.

The consonant/vowel pattern determines the structure of orthographic representations in the left fusiform gyrus.

Recent findings demonstrated readers' sensitivity to the distinction between consonant and vowel letters. Especially, the way consonants and vowels are organised within written words determines their perceptual structure. The present work attempted to overcome two limitations of previous studies by examining the neurophysiological correlates of this perceptual structure through magnetoencephalography (MEG). One aim was to establish that the extraction of vowel-centred units takes place during early stages of processing. The second objective was to confirm that the vowel-centred structure pertains to the word recognition system and may constitute one level in a hierarchy of neural detectors coding orthographic strings. Participants performed a cross-case matching task in which they had to judge pairs of stimuli as identical or different. The critical manipulation concerned pairs obtained by transposing two letters, so that the vowel-centred structure was either preserved (FOUVERT-fovuert, two vowel letter clusters) or modified (BOUVRET-bovuret). Mismatches were detected faster when the structure was modified. This effect was associated with a significant difference in evoked neuromagnetic fields extending from 129 to 239 msec after the stimulation. Source localization indicated a significant effect in the visual word form area around 200 msec. The results confirm the hypothesis that the vowel-centred structure is extracted during the early phases of letter string processing and that it is encoded in left fusiform regions devoted to visual word recognition.

What can megastudies tell us about the orthographic structure of English words?

Although the majority of research in visual word recognition has targeted single-syllable words, most words are polysyllabic. These words engender special challenges, one of which concerns their analysis into smaller units. According to a recent hypothesis, the organization of letters into groups of successive consonants (C) and vowels (V) constrains the orthographic structure of printed words. So far, evidence has been reported only in French with factorial studies of relatively small sets of items. In the present study, we performed regression analyses on corpora of megastudies (English and British Lexicon Project databases) to examine the influence of the CV pattern in English. We compared hiatus words, which present a mismatch between the number of syllables and the number of groups of adjacent vowel letters (e.g., client), to other words, controlling for standard lexical variables. In speeded pronunciation, hiatus words were processed more slowly than control words, and the effect was stronger in low-frequency words. In the lexical decision task, the interference effect of hiatus in low-frequency words was balanced by a facilitatory effect in high-frequency words. Taken together, the results support the hypothesis that the configuration of consonant and vowel letters influences the processing of polysyllabic words in English.

The role of the syllable in lexical segmentation in French: word-spotting data.

Three word-spotting experiments assessed the role of syllable onsets and offsets in lexical segmentation. Participants detected CVC words embedded initially or finally in bisyllabic nonwords with aligned (CVC.CVC) or misaligned (CV.CCVC) syllabic structure. A misalignment between word and syllable onsets (Experiment 1) produced a greater perceptual cost than a misalignment between word and syllable offsets (Experiments 2 and 3). These results suggest that listeners rely on syllable onsets to locate the beginning of words. The implications for theories of lexical access in continuous speech are discussed.

The role of consonant/vowel organization in perceptual discrimination.

According to a recent hypothesis, the CV pattern (i.e., the arrangement of consonant and vowel letters) constrains the mental representation of letter strings, with each vowel or vowel cluster being the core of a unit. Six experiments with the same/different task were conducted to test whether this structure is extracted prelexically. In the mismatching trials, the targets were pseudowords built by the transposition of 2 adjacent letters from base words. In one condition, the pseudowords had the same number of vowel clusters as the base word, whereas in another condition, the transposition modified the number of vowel clusters (e.g., poirver: 2 vowel clusters vs. povirer: 3 vowel clusters, from POIVRER: 2 vowel clusters). In Experiment 1, pseudowords with a different number of vowel clusters were more quickly processed than pseudowords preserving the CV structure of their base word. Experiment 2 further showed that this effect was not due to changes in syllabic structure. In Experiment 3, the pattern of results was also replicated when the category (consonant or vowel) of the transposed letters was strictly equated between conditions. Experiments 4 and 5 confirmed that the effects were not attributable to lexical processing, to differences in letter identity, or to the position of transpositions. The results suggest that the orthographic representation of letter strings is influenced by the CV pattern at an early, prelexical processing stage.