Rational inattention: A new theory of neurodivergent information seeking.

This paper presents rational inattention as a new, transdiagnostic theory of information seeking in neurodevelopmental conditions that have uneven cognitive and socio-emotional profiles, including developmental language disorder (DLD), dyslexia, dyscalculia and autism. Rational inattention holds that the optimal solution to minimizing epistemic uncertainty is to avoid imprecise information sources. The key theoretical contribution of this report is to endogenize imprecision, making it a function of the primary neurocognitive difficulties that have been invoked to explain neurodivergent phenotypes, including deficits in auditory perception, working memory, procedural learning and the social brain network. We argue that disengagement with information sources with low endogenous precision (e.g. speech in DLD, orthography-phonology mappings in dyslexia, numeric stimuli in dyscalculia and social signals in autism) constitutes resource-rational behaviour. We demonstrate the strength of this account in a series of computational simulations. In experiment 1, we simulate information seeking in artificial agents mimicking an array of neurodivergent phenotypes, which optimally explore a complex learning environment containing speech, text, numeric stimuli and social cues. In experiment 2, we simulate optimal information seeking in a cross-modal dual-task paradigm and qualitatively replicate empirical data from children with and without DLD. Across experiments, simulated agents' only aim was to maximally reduce epistemic uncertainty, with no difference in reward across information sources. We show that rational inattention emerges naturally in specific neurodivergent phenotypes as a function of low endogenous precision. For instance, an agent mimicking the DLD phenotype disengages with speech (and preferentially engages with alternative precise information sources) because endogenous imprecision renders speech not conducive to information gain. Because engagement is necessary for learning, simulation demonstrates how optimal information seeking may paradoxically contribute negatively to an already delayed learning trajectory in neurodivergent children. RESEARCH HIGHLIGHTS: We present the first comprehensive theory of information seeking in neurodivergent children to date, centred on the notion of rational inattention. We demonstrate the strength of this account in a series of computational simulations involving artificial agents mimicking specific neurodivergent phenotypes that optimally explore a complex learning environment containing speech, text, numeric stimuli, and social cues. We show how optimal information seeking may, paradoxically, contribute negatively to an already delayed learning trajectory in neurodivergent children. This report advances our understanding of the factors shaping short-term decision making and long-term learning in neurodivergent children.

SUBTLEX-CY: A new word frequency database for Welsh.

We present SUBTLEX-CY, a new word frequency database created from a 32-million-word corpus of Welsh television subtitles. An experiment comprising a lexical decision task examined SUBTLEX-CY frequency estimates against words with inconsistent frequencies in a much smaller Welsh corpus that is often used by researchers, the Cronfa Electroneg o'r Gymraeg (CEG), and three other Welsh word frequency databases. Words were selected that were classified as low frequency (LF) in SUBTLEX-CY and high frequency (HF) in CEG and compared with words that were classified as medium frequency (MF) in both SUBTLEX-CY and CEG. Reaction time analyses showed that HF words in CEG were responded to more slowly compared to MF words, suggesting that SUBTLEX-CY corpus provides a more reliable estimate of Welsh word frequencies. The new Welsh word frequency database that also includes part-of-speech, contextual diversity, and other lexical information is freely available for research purposes on the Open Science Framework repository at https://osf.io/9gkqm/.

Medication-invariant resting aperiodic and periodic neural activity in Parkinson's disease.

Parkinson's disease (PD) has been associated with greater total power in canonical frequency bands (i.e., alpha, beta) of the resting electroencephalogram (EEG). However, PD has also been associated with a reduction in the proportion of total power across all frequency bands. This discrepancy may be explained by aperiodic activity (exponent and offset) present across all frequency bands. Here, we examined differences in the eyes-open (EO) and eyes-closed (EC) resting EEG of PD participants (N = 26) on and off medication, and age-matched healthy controls (CTL; N = 26). We extracted power from canonical frequency bands using traditional methods (total alpha and beta power) and extracted separate parameters for periodic (parameterized alpha and beta power) and aperiodic activity (exponent and offset). Cluster-based permutation tests over spatial and frequency dimensions indicated that total alpha and beta power, and aperiodic exponent and offset were greater in PD participants, independent of medication status. After removing the exponent and offset, greater alpha power in PD (vs. CTL) was only present in EO recordings and no reliable differences in beta power were observed. Differences between PD and CTL in the resting EEG are likely driven by aperiodic activity, suggestive of greater relative inhibitory neural activity and greater neuronal spiking. Our findings suggest that resting EEG activity in PD is characterized by medication-invariant differences in aperiodic activity which is independent of the increase in alpha power with EO. This highlights the importance of considering aperiodic activity contributions to the neural correlates of brain disorders.

The impact of phonological relatedness on semantic congruency judgements in readers with dyslexia: Evidence from behavioural judgements, event related potentials and pupillometry.

Readers with developmental dyslexia are known to be impaired in representing and accessing phonology, but their ability to process meaning is generally considered to be intact. However, neurocognitive studies show evidence of a subtle semantic processing deficit in dyslexic readers, relative to their typically-developing peers. Here, we compared dyslexic and typical adult readers on their ability to judge semantic congruency (congruent vs. inconcongruent) in short, two-word phrases, which were further manipulated for phonological relatedness (alliterating vs. non-alliterating); "dazzling-diamond"; "sparkling-diamond"; "dangerous-diamond"; and "creepy-diamond". At the level of behavioural judgement, all readers were less accurate when evaluating incongruent alliterating items compared with incongruent non-aliterating, suggesting that phonological patterning creates the illusion of semantic congruency (as per Egan et al., 2020). Dyslexic readers showed a similar propensity for this form-meaning relationship despite a phonological processing impairment as evidenced in the cognitive and literacy indicative assessments. Dyslexic readers also showed an overall reduction in the ability to accurately judge semantic congruency, suggestive of a subtle semantic impairment. Whilst no group differences emerged in the electrophysiological measures, our pupil dilation measurements revealed a global tendency for dyslexic readers to manifest a reduced attentional response to these word stimuli, compared with typical readers. Our results show a broad manifestation of neurocognitive differences in adult dyslexic and typical readers' processing of print, at the level of autonomic arousal as well as in higher level semantic judgements.

As clear as glass: How figurativeness and familiarity impact simile processing in readers with and without dyslexia.

For skilled readers, idiomatic language confers faster access to overall meaning compared with non-idiomatic language, with a processing advantage for figurative over literal interpretation. However, currently very little research exists to elucidate whether atypical readers-such as those with developmental dyslexia-show such a processing advantage for figurative interpretations of idioms, or whether their reading impairment implicates subtle differences in semantic access. We wanted to know whether an initial figurative interpretation of similes, for both typical and dyslexic readers, is dependent on familiarity. Here, we tracked typical and dyslexic readers' eye movements as they read sentences containing similes (e.g., as cold as ice), orthogonally manipulated for novelty (e.g., familiar: as cold as ice, novel: as cold as snow) and figurativeness (e.g., literal: as cold as ice [low temperature], figurative: as cold as ice [emotionally distant]), with figurativeness being defined by the sentence context. Both participant groups exhibited a processing advantage for familiar and figurative similes over novel and literal similes. However, compared with typical readers, participants with dyslexia had greater difficulty processing similes both when they were unfamiliar and when the context biased the simile meaning towards a literal rather than a figurative interpretation. Our findings suggest a semantic processing anomaly in dyslexic readers, which we discuss in light of recent literature on sentence-level semantic processing.

Audiovisual Learning in Dyslexic and Typical Adults: Modulating Influences of Location and Context Consistency.

Learning to read involves efficient binding of visual to auditory information. Aberrant cross-modal binding skill has been observed in both children and adults with developmental dyslexia. Here, we examine the contribution of episodic memory to acquisition of novel cross-modal bindings in typical and dyslexic adult readers. Participants gradually learned arbitrary associations between unfamiliar Mandarin Chinese characters and English-like pseudowords over multiple exposures, simulating the early stages of letter-to-letter sound mapping. The novel cross-modal bindings were presented in consistent or varied locations (i.e., screen positions), and within consistent or varied contexts (i.e., co-occurring distractor items). Our goal was to examine the contribution, if any, of these episodic memory cues (i.e., the contextual and spatial properties of the stimuli) to binding acquisition, and investigate the extent to which readers with and without dyslexia would differ in their reliance on episodic memory during the learning process. Participants were tested on their ability to recognize and recall the bindings both during training and then in post-training tasks. We tracked participants' eye movements remotely with their personal webcams to assess whether they would re-fixate relevant empty screen locations upon hearing an auditory cue-indicative of episodic memory retrieval-and the extent to which the so-called "looking-at-nothing behavior" would modulate recognition of the novel bindings. Readers with dyslexia both recognized and recalled significantly fewer bindings than typical readers, providing further evidence of their persistent difficulties with cross-modal binding. Looking-at-nothing behavior was generally associated with higher recognition error rates for both groups, a pattern that was particularly more evident in later blocks for bindings encoded in the inconsistent location condition. Our findings also show that whilst readers with and without dyslexia are capable of using stimulus consistencies in the input-both location and context-to assist in audiovisual learning, readers with dyslexia appear particularly reliant on consistent contextual information. Taken together, our results suggest that whilst readers with dyslexia fail to efficiently learn audiovisual binding as a function of stimulus frequency, they are able to use stimulus consistency-aided by episodic recall-to assist in the learning process.

How alliteration enhances conceptual-attentional interactions in reading.

In linguistics, the relationship between phonological word form and meaning is mostly considered arbitrary. Why, then, do literary authors traditionally craft sound relationships between words? We set out to characterise how dynamic interactions between word form and meaning may account for this literary practice. Here, we show that alliteration influences both meaning integration and attentional engagement during reading. We presented participants with adjective-noun phrases, having manipulated semantic relatedness (congruent, incongruent) and form repetition (alliterating, non-alliterating) orthogonally, as in "dazzling-diamond"; "sparkling-diamond"; "dangerous-diamond"; and "creepy-diamond". Using simultaneous recording of event-related brain potentials and pupil dilation (PD), we establish that, whilst semantic incongruency increased N400 amplitude as expected, it reduced PD, an index of attentional engagement. Second, alliteration affected semantic evaluation of word pairs, since it reduced N400 amplitude even in the case of unrelated items (e.g., "dangerous-diamond"). Third, alliteration specifically boosted attentional engagement for related words (e.g., "dazzling-diamond"), as shown by a sustained negative correlation between N400 amplitudes and PD change after the window of lexical integration. Thus, alliteration strategically arouses attention during reading and when comprehension is challenged, phonological information helps readers link concepts beyond the level of literal semantics. Overall, our findings provide a tentative mechanism for the empowering effect of sound repetition in literary constructs.

Bilinguals apply language-specific grain sizes during sentence reading.

Languages differ in the consistency with which they map orthography to phonology, and a large body of work now shows that orthographic consistency determines the style of word decoding in monolinguals. Here, we characterise word decoding in bilinguals whose two languages differ in orthographic consistency, assessing whether they maintain two distinct reading styles or settle on a single 'compromise' reading style. In Experiment 1, Welsh-English bilinguals read cognates and pseudowords embedded in Welsh and English sentences. Eye-movements revealed that bilinguals dynamically alter their decoding strategy according to the language context, including more fixations during lexical access for cognates in the more consistent orthography (Welsh) than in the less consistent orthography (English), and these effects were specific to word (as opposed to pseudoword) processing. In Experiment 2, we compared the same bilinguals' eye movements in the English sentence reading context to those of monolinguals'. Bilinguals' eye-movement behaviour was very similar to monolinguals' when reading English, suggesting that their knowledge of the more consistent orthography (Welsh) did not alter their decoding style when reading in English. This study presents the first characterisation of bilingual decoding style in sentence reading. We discuss our findings in relation to connectionist reading models and models of bilingual visual word recognition.

Language and transient emotional states affect implicit cultural bias.

Bilinguals react to cultural information in a language-dependent fashion, but it is unknown whether this is influenced by the individual's emotional state. Here, we show that induced mood states increase cultural bias-measured using the Implicit Association Test (IAT)-but this effect occurs asymmetrically across languages. In the native language, bilinguals show a strong cultural bias, which is not influenced by mood. But in the non-native language, a relatively low cultural bias significantly increases as a function of a positive or negative mood. Our findings suggest that the native language promotes an inherent cultural bias, which is impervious to fluctuations in the bilingual's mood state. In the second language, however, bilinguals are culturally impartial, unless they are in a heightened mood state.

Timeline blurring in fluent Chinese-English bilinguals.

Linguistic relativity effects arising from differences in terminology and syntax between languages have now been established in various domains of human cognition. Although metaphors have been shown to affect time conceptualisation, there is little evidence to date that the presence or absence of tense within a given language can affect how one processes temporal sequences of events. Here, we set out to characterise how native speakers of Mandarin Chinese - a tenseless language- deal with reference time misalignment using event-related brain potentials. Fluent Chinese-English participants and native speakers of English made acceptability judgements on sentences in which the adjunct clause started with the connective 'after' and was either temporally aligned or not with the main clause in terms of reference time conveyed by the verb. Native speakers of English failed to overtly report such reference time misalignments between clauses, but significant N400 modulations showed that they nevertheless required additional semantic processing effort. Chinese speakers, however, showed no such N400 modulation suggesting that they did not covertly detect reference time misalignments between clauses in real time. Critically, all participants manifested normal sentence comprehension as shown by a standard N400 semantic violation elicited by incongruent endings. We conclude that Chinese speakers of English experience difficulties locating events on a timeline in relation to one another when temporal information is conveyed by tense.

Episodic traces and statistical regularities: Paired associate learning in typical and dyslexic readers.

Learning visual-phonological associations is a key skill underlying successful reading acquisition. However, we are yet to understand the cognitive mechanisms that enable efficient learning in good readers, and those which are aberrant in individuals with developmental dyslexia. Here, we use a repeated cued-recall task to examine how typical and reading-impaired adults acquire novel associations between visual and phonological stimuli, incorporating a looking-at-nothing paradigm to probe implicit memory for target locations. Cued recall accuracy revealed that typical readers' recall of novel phonological associates was better than dyslexic readers' recall, and it also improved more with repetition. Eye fixation-contingent error analyses suggest that typical readers' greater improvement from repetition reflects their more robust encoding and/or retrieval of each instance in which a given pair was presented: whereas dyslexic readers tended to recall a phonological target better when fixating its most recent location, typical readers showed this pattern more strongly when the target location was consistent across multiple trials. Thus, typical readers' greater success in reading acquisition may derive from their better use of statistical contingencies to identify consistent stimulus features across multiple exposures. We discuss these findings in relation to the role of implicit memory in forming new visual-phonological associations as a foundational skill in reading, and areas of weakness in developmental dyslexia.

Abstract images and words can convey the same meaning.

Intuitively, deriving meaning from an abstract image is a uniquely human, idiosyncratic experience. Here we show that, despite having no universally recognised lexical association, abstract images spontaneously elicit specific concepts conveyed by words, with a consistency akin to that of concrete images. We presented a group of naïve participants with abstract picture-word pairs construed as 'related' or 'unrelated' according to a preliminary norming procedure conducted with different participants. Surprisingly, the naïve participants with no prior exposure to the abstract images or any hints regarding their possible meaning, displayed a reaction time priming effect for 'related' versus 'unrelated' picture-word pairs. Critically, this behavioural priming effect, and an associated decrease in N400 mean amplitude indexing semantic priming, both correlated significantly with the degree of relatedness established in the preliminary norming procedure. Given that ratings and electrophysiological measures were obtained in different groups of individuals, our results show that abstract images evoke consistent meaning across observers, as has been shown in the case of music.

Lexical Reading in Dysfluent Readers of German.

Dyslexia in consistent orthographies like German is characterized by dysfluent reading, which is often assumed to result from failure to build up an orthographic lexicon and overreliance on decoding. However, earlier evidence indicates effects of lexical processing at least in some German dyslexic readers. We investigated variations in reading style in an eye-tracking paradigm with German dysfluent 3rd and 4th graders. Twenty-six TypFix-readers (fixation counts within the range of 47 age-matched typical readers) were compared with 42 HighFix-readers (increased fixation counts). Both groups showed lexical access: Words were read more efficiently than nonwords and pseudohomophones. TypFix-readers showed stronger reliance on lexical reading than HighFix-readers (smaller length effects for number of fixations and total reading time, stronger lexicality effects for gaze duration, stronger word-pseudohomophone effects for mean saccade amplitude). We conclude that in both groups, sublexical and lexical reading processes were impaired due to inefficient visual-verbal integration.

Implicit Detection of Poetic Harmony by the Naïve Brain.

The power of poetry is universally acknowledged, but it is debatable whether its appreciation is reserved for experts. Here, we show that readers with no particular knowledge of a traditional form of Welsh poetry unconsciously distinguish phrases conforming to its complex poetic construction rules from those that violate them. We studied the brain response of native speakers of Welsh as they read meaningful sentences ending in a word that either complied with strict poetic construction rules, violated rules of consonantal repetition, violated stress pattern, or violated both these constraints. Upon reading the last word of each sentence, participants indicated sentence acceptability. As expected, our inexperienced participants did not explicitly distinguish between sentences that conformed to the poetic rules from those that violated them. However, in the case of orthodox sentences, the critical word elicited a distinctive brain response characteristic of target detection -the P3b- as compared to the other conditions, showing that speakers of Welsh with no expertise of this particular form of poetry implicitly detect poetic harmony. These results show for the first time that before we even consider literal meaning, the musical properties of poetry speak to the human mind in ways that escape consciousness.

ERPs Reveal the Time-Course of Aberrant Visual-Phonological Binding in Developmental Dyslexia.

New evidence is accumulating for a deficit in binding visual-orthographic information with the corresponding phonological code in developmental dyslexia. Here, we identify the mechanisms underpinning this deficit using event-related brain potentials (ERPs) in dyslexic and control adult readers performing a letter-matching task. In each trial, a printed letter was presented synchronously with an auditory letter name. Incongruent (mismatched), frequent trials were interleaved with congruent (matched) infrequent target pairs, which participants were asked to report by pressing a button. In critical trials, incongruent letter pairs were mismatched but confusable in terms of their visual or phonological features. Typical readers showed early detection of deviant trials, indicated by larger modulation in the range of the phonological mismatch negativity (PMN) compared with standard trials. This was followed by stronger modulation of the P3b wave for visually confusable deviants and an increased lateralized readiness potential (LRP) for phonological deviants, compared with standards. In contrast, dyslexic readers showed reduced sensitivity to deviancy in the PMN range. Responses to deviants in the P3b range indicated normal letter recognition processes, but the LRP calculation revealed a specific impairment for visual-orthographic information during response selection in dyslexia. In a follow-up experiment using an analogous non-lexical task in the same participants, we found no reading-group differences, indicating a degree of specificity to over-learnt visual-phonological binding. Our findings indicate early insensitivity to visual-phonological binding in developmental dyslexia, coupled with difficulty selecting the correct orthographic code.

What automaticity deficit? Activation of lexical information by readers with dyslexia in a rapid automatized naming Stroop-switch task.

Reading fluency is often predicted by rapid automatized naming (RAN) speed, which as the name implies, measures the automaticity with which familiar stimuli (e.g., letters) can be retrieved and named. Readers with dyslexia are considered to have less "automatized" access to lexical information, reflected in longer RAN times compared with nondyslexic readers. We combined the RAN task with a Stroop-switch manipulation to test the automaticity of dyslexic and nondyslexic readers' lexical access directly within a fluency task. Participants named letters in 10 × 4 arrays while eye movements and speech responses were recorded. Upon fixation, specific letter font colors changed from black to a different color, whereupon the participant was required to rapidly switch from naming the letter to naming the letter color. We could therefore measure reading group differences on "automatic" lexical processing, insofar as it was task-irrelevant. Readers with dyslexia showed obligatory lexical processing and a timeline for recognition that was overall similar to typical readers, but a delay emerged in the output (naming) phase. Further delay was caused by visual-orthographic competition between neighboring stimuli. Our findings outline the specific processes involved when researchers speak of "impaired automaticity" in dyslexic readers' fluency, and are discussed in the context of the broader literature in this field.

Language and culture modulate online semantic processing.

Language has been shown to influence non-linguistic cognitive operations such as colour perception, object categorization and motion event perception. Here, we show that language also modulates higher level processing, such as semantic knowledge. Using event-related brain potentials, we show that highly fluent Welsh-English bilinguals require significantly less processing effort when reading sentences in Welsh which contain factually correct information about Wales, than when reading sentences containing the same information presented in English. Crucially, culturally irrelevant information was processed similarly in both Welsh and English. Our findings show that even in highly proficient bilinguals, language interacts with factors associated with personal identity, such as culture, to modulate online semantic processing.

Anomalous transfer of syntax between languages.

Each human language possesses a set of distinctive syntactic rules. Here, we show that balanced Welsh-English bilinguals reading in English unconsciously apply a morphosyntactic rule that only exists in Welsh. The Welsh soft mutation rule determines whether the initial consonant of a noun changes based on the grammatical context (e.g., the feminine noun cath--"cat" mutates into gath in the phrase y gath--"the cat"). Using event-related brain potentials, we establish that English nouns artificially mutated according to the Welsh mutation rule (e.g., "goncert" instead of "concert") require significantly less processing effort than the same nouns implicitly violating Welsh syntax. Crucially, this effect is found whether or not the mutation affects the same initial consonant in English and Welsh, showing that Welsh syntax is applied to English regardless of phonological overlap between the two languages. Overall, these results demonstrate for the first time that abstract syntactic rules transfer anomalously from one language to the other, even when such rules exist only in one language.

Naming fluency in dyslexic and nondyslexic readers: differential effects of visual crowding in foveal, parafoveal, and peripheral vision.

Reading fluency is often indexed by performance on rapid automatized naming (RAN) tasks, which are known to reflect speed of access to lexical codes. We used eye tracking to investigate visual influences on naming fluency. Specifically, we examined how visual crowding affects fluency in a RAN-letters task on an item-by-item basis, by systematically manipulating the interletter spacing of items, such that upcoming letters in the array were viewed in the fovea, parafovea, or periphery relative to a given fixated letter. All lexical information was kept constant. Nondyslexic readers' gaze durations were longer in foveal than in parafoveal and peripheral trials, indicating that visual crowding slows processing even for fluent readers. Dyslexics' gaze durations were longer in foveal and parafoveal trials than in peripheral trials. Our results suggest that for dyslexic readers, influences of crowding on naming speed extend to a broader visual span (to parafoveal vision) than that for nondyslexic readers, but do not extend as far as peripheral vision. The findings extend previous research by elucidating the different visual spans within which crowding operates for dyslexic and nondyslexic readers in an online fluency task.

Cross-modal binding in developmental dyslexia.

The ability to learn visual-phonological associations is a unique predictor of word reading, and individuals with developmental dyslexia show impaired ability in learning these associations. In this study, we compared developmentally dyslexic and nondyslexic adults on their ability to form cross-modal associations (or "bindings") based on a single exposure to pairs of visual and phonological features. Reading groups were therefore compared on the very early stages of associative learning. We used a working memory framework-including experimental designs used to investigate cross-modal binding. Two change-detection experiments showed a group discrepancy in binding that was dependent on spatial location encoding: Whereas group performance was similar when location was an inconsistent cue (Experiment 1), nondyslexic readers showed higher accuracy in binding than dyslexics when location was a consistent cue (Experiment 2). A cued-recall task confirmed that location information discriminates binding ability between reading groups in a more explicit memory recall task (Experiment 3). Our results show that recall for ephemeral cross-modal bindings is supported by location information in nondyslexics, but this information cannot be used to similar effect in dyslexic readers. Our findings support previous demonstrations of cross-modal association difficulty in dyslexia and show that a group discrepancy exists even in a single, initial presentation of visual-phonological pairs. Effective use of location information as a retrieval cue is one mechanism that discriminates reading groups, which may contribute to the longer term cross-modal association problems characteristic of dyslexia.