Developmental Science

Visual orthographic knowledge plays a critical role in early literacy development and may provide a shared foundation for reading and spelling, yet the nature of its underlying representations remains debated. Behavioral measures offer indirect evidence and may be influenced by other metalinguistic processes. It remains unclear whether beginning readers encode larger orthographic structures, such as onset-rime units, beyond individual letters and smaller letter combinations but below the whole-word level. It is also unknown whether neural sensitivity to these structures helps explain the relationship between spelling and reading. To address these questions, we used a fast periodic visual stimulation (FPVS) paradigm in first- and second-grade children to contrast pseudowords constructed with the typical ordering of onset followed by rime elements (i.e., onset-rime) against matched strings in which the same elements appeared in the reverse order (i.e., rime-onset). Neural sensitivity to onset-rime orthographic structure was associated with both spelling ability and word-reading efficiency and, critically, statistically mediated the relationship between these two literacy skills. These relationships remained significant after controlling for age and removing influential observations, and sensitivity to onset-rime orthographic structure explained additional variance in word-reading efficiency beyond spelling ability and age. Together, these findings provide neurophysiological evidence for onset-rime structure as an important sublexical orthographic unit in beginning readers, highlighting its potential role in linking spelling with efficient word recognition during early reading development.

Newborns recognise familiar language patterns experienced in utero and discriminate them from unfamiliar ones. It is as yet unclear which neural mechanisms are responsible for such early language-specific behavior. Here we focus on neural speech tracking and test whether it shows language-specific attunement in newborns and one-to-two month olds. Infants listened to infant-directed stories in their native language (Czech) and an unfamiliar language (Russian) while their EEG was recorded. First, we examined whether neural speech tracking differed between infants predominantly exposed to Czech and infants exposed primarily to other languages. Second, we assessed developmental changes by combining these data with a previously collected cohort of newborns, yielding a continuous sample spanning 1-62 days of age. Neural speech tracking was assessed in stimulus-derived delta and theta frequency bands in terms of oscillatory power and accuracy of EEG-to-speech envelope reconstruction using the backward multivariate temporal response functions. Czech-exposed infants had stronger cortical tracking of Czech speech than infants exposed to other languages. Within the Czech-exposed group, native Czech elicited stronger neural tracking than unfamiliar Russian, particularly in the delta band, indicating early language-specific tuning to the prosodic-word structure. Across the combined Czech-exposed sample, this native-language advantage gradually decreased with age, suggesting that neural speech tracking of the slow rhythms undergoes rapid reorganization during the first two months of life. These findings demonstrate that language-specific neural speech tracking is detectable from the earliest weeks of life and is jointly shaped by early, perinatal language experience as well as cognitive maturation.

Selective attention, the ability to focus on relevant information while ignoring task-irrelevant information, is crucial for learning. Selective attention has largely been studied in motionless individuals. However, body movements are intrinsic to cognition and particularly frequent in children. To test whether movements explain successful attention control throughout childhood, we tracked head rotations while younger children (6-8 years, n = 25), older children (9-10 years, n = 20) and adults (18-30 years; n = 21) identified a spatial target sound under distraction. Distractor reports decreased with age, confirming a developmental increase in attention control. Importantly, a dissociation of two distinct types of movement emerged: Task-dependent head rotation to lateral targets was similar across age groups. Contrary, task-independent movements before and early during a trial decreased with age and predicted attention accuracy. Thus, movements unrelated to the attention goal do not reflect noise but signify attentional control across development.

This study examined whether emotional valence modulates face working memory precision in adolescents with specific learning disorders (SLD) and whether mnemonic distortions differ across subtypes. Fifty-four adolescents with SLD (dyslexia: n = 19; dysgraphia: n = 18; dyscalculia: n = 17) and 42 typically developing peers completed a morphed delayed reproduction task using sad, neutral, and happy faces. Using a von Mises + uniform mixture model, we decomposed recall errors into precision, systematic bias, and guessing. The SLD group made significantly larger errors (r = 8722;0.61) and responded more slowly (r = -0.33). Mixture modeling showed that deficits arose from reduced precision ({kappa}: TD M = 8.72 vs. SLD M = 4.15; r = 0.54) and stronger systematic bias toward neutrality (: TD M = -0.66 vs. SLD M = -4.15; r = 0.34), with no differences in random guessing. Valence flattening was consistently larger in SLD. Among subtypes, dyscalculia showed the greatest working memory impairment, yet all three exhibited the same valence flattening pattern. Thus, emotional faces disrupt face working memory in SLD through reduced precision and systematic affective distortion. The bias parameter from mixture modeling may offer a clinically useful metric for subtype-sensitive assessment.

Empirical evidence from traditional inhibitory control tasks regarding inhibitory deficits in high autistic traits has been mixed, indicating that this issue remains controversial. Although sex differences are widely documented in autistic cognitive profiles, their role in inhibitory gating mechanisms remains underexplored. Given that the expression of inhibitory gating deficits may be modulated by the social versus non-social nature of stimuli, and no prior study has investigated this topic by integrating both sex differences and stimulus domain, we addressed these two questions with the attribute amnesia paradigm. We manipulated stimulus type (non-social vs. social). In Experiment 1, participants performed a location task with animal drawings as targets and were unexpectedly asked to report animal identity on a surprise trial. High autistic trait females showed significantly higher accuracy on the surprise trial than all other groups, reflecting a failure to actively filter out task-irrelevant non-social information, that is, a reduced inhibitory gating efficiency. In Experiment 2, using face stimuli and a self-vs. other-face design, this gating deficit was no longer expressed: all groups performed at chance levels on the identity judgment, regardless of autistic trait level, sex, or face type. This dissociation aligns with a dual-mechanism framework: the inhibitory gating deficit in high autistic trait females is specific to non-social stimuli and masked by camouflaging for social ones. This study demonstrates that the inhibitory gating deficit in high autistic trait females is not a global impairment but rather a stimulus-dependent one, highlighting the need to consider sex and stimulus type.

Attention is foundational to learning, yet the extent to which features of the instructional environment differentially shape attentional engagement is not well understood. Here we leveraged mobile EEG and video-coded behavioral observation to examine attentional engagement in 6 to 10 years old children with and without a diagnosis of ADHD across instructional conditions varying in delivery modality (video watching, online, in-person) and management of learning (teacher-led versus student-led). EEG measures, including alpha-band (8-12Hz) oscillations, spectral slope and offset, and behavioral measures of active engagement (AE%), passive engagement (PE%), fidgeting, off-task behavior, were examined as a function of instructional context. Attentional engagement, as indicated by higher AE%, lower alpha power, flatter spectral slope and lower offset, was greatest in student-led learning, followed by teacher-led in person learning, synchronous online learning, and asynchronous learning, respectively. Child by instructional context interactions revealed that patterns of attentional engagement were largely consistent regardless of diagnosis, with group effects observed for motor behaviors (PE%, fidgeting) but not for measures of visual attention. Similarly, age showed only main effects, whereby older children showed higher passive engagement, lower fidgeting and off-task behavior, flatter spectral slope, and lower offset. The results underscore: (i) the importance of considering environmental context, such as instructional modality and management of learning, when examining mechanisms of attention and individual differences therein, and (ii) the value of recording multiple behavioral and neural measures, as not all indices commonly assumed to reflect attention capture the same underlying processes.

Background: Infant muscle tone reflects early central nervous system integrity and has been associated with later motor and cognitive development, including autism traits. The cerebellum regulates both motor control and higher-order socio-cognitive functions and has been repeatedly implicated in autism, but its role in linking infant muscle tone to adolescent autistic traits has not previously been studied in a large, prospective population cohort. Methods: We used data from the prospective Generation R Study. Infant muscle tone (hypotonia and hypertonia) was assessed via Prechtl examination, and third-trimester fetal transcerebellar diameter was measured using ultrasound n=6,842). Cerebellar morphology at ages 6, 10, and 14 years (n=4,861) was measured using structural MRI. Linear mixed-effects models tested associations between infant muscle tone and 35 anatomical and 10 functional cerebellar regions. Causal mediation models tested whether cerebellar volume mediated associations between infant muscle tone and adolescent autistic traits at age 14 (Social Responsiveness Scale). Results: Hypotonia predicted larger vermis IX volumes across childhood (beta=0.037, pFDR =0.043). Hypertonia showed an age-dependent association with left lateral lobule IX (beta=-0.0027, pFDR =0.041), with differences diminishing with age. Third-trimester transcerebellar diameter did not predict postnatal muscle tone. Given its significant main effect, vermis IX volume was tested as a mediator, but did not mediate the pathway to adolescent autistic traits. However, infant hypotonia showed a small direct association with elevated autistic traits at age 14, specific to girls (beta=0.0255, p=0.020). Conclusions: Infant muscle tone is associated with localized differences in cerebellar volumes. These associations are specific to vermal and left hemispheric lobule IX, a region commonly implicated in spinocerebellar postural control, axial stability, and higher-order sensorimotor integration. Furthermore, infant muscle tone was not predicted by prenatal cerebellar diameter, and cerebellar volumes did not mediate the association between infant hypotonia and adolescent autistic traits in our study. Future research should further investigate these findings in clinical populations, integrating longitudinal whole-brain, multi-modal imaging to clarify the association between infant muscle tone, the cerebellar functioning, and autistic traits.

Atypical sensory processing is common in attention-deficit/hyperactivity disorder (ADHD), yet decreased sound tolerance has received little attention, and it remains unclear whether it reflects actual auditory sensitivity or a vulnerability to attentional breakdown under acoustic load. The only prior study provided a single overall estimate, unable to separate sensory symptoms such as avoidance and distress from attentional and fatigue-related difficulties under noisy or demanding conditions. Here, we examined whether parent-reported auditory difficulties in children with ADHD are uniform or concentrated within specific symptom domains, and whether they vary with clinical presentation or medication. A total of 226 children (ages 6-12; 162 with ADHD, 64 typically developing controls) were assessed using the parent-report adaptation of the Khalfa Hyperacusis Questionnaire (Turkish version). The ADHD cohort was stratified by medication status and clinical presentation, and total, subscale, and item-level scores were compared across groups. Our findings show that children with ADHD scored higher than controls on the total and hyperacusis-effects subscale, but not on the coping subscale. Only four of the eleven items distinguished the groups, all reflecting concentration in noise or its decline under fatigue; no item reflecting sound avoidance, sensitivity, or distress differed between groups. This pattern was independent of clinical presentation, medication, and age; it persisted after adjustment for parental education. These results suggest that elevated auditory difficulties in ADHD are better explained by attention- and fatigue-related vulnerability than by heightened auditory sensitivity and may warrant environmental rather than audiological interventions.

In the context of education, attention can be considered the gateway for learning, yet it remains unclear which neural mechanisms of attention identified under controlled laboratory conditions are most relevant when children engage in meaningful learning. Here, we addressed this question by experimentally manipulating attention while 5th- and 6th-grade students learned novel educational content from their own teacher. Working in partnership with an experienced classroom teacher, we co-developed naturalistic auditory and visual learning streams and manipulated whether students prioritized or ignored the speech. Using school-based electroencephalography and temporal response function modeling, we examined whether attention modulated early sensory or later stages of cortical speech processing. Attention selectively modulated speech processing at approximately 170 ms, with no evidence for modulation at earlier sensory stages, supporting a predominant role for late-stage attentional selection during learning. Importantly, individual differences in attentional modulation were associated with learning: students who more strongly increased neural tracking of the speech when it was task-relevant learned more effectively from spoken instruction. The same late-stage neural mechanism also distinguished students whom their teacher independently identified as stronger attenders during everyday classroom learning. Together, these findings connect late-stage attentional modulation across experimental neural dynamics, individual learning outcomes, and teacher observations of classroom behavior. More broadly, they demonstrate how studying attention within educationally meaningful contexts can help identify which neural mechanisms are most consequential for successful learning.

Whether subjective colour experience (e.g., experience of 'red') is shared across children and adults remains a foundational question in developmental psychology and consciousness research. To test this, we compared the relational structures of their colour experiences and identified the mapping that best preserved these structures. Using pairwise similarity judgements for 13 basic colours, we applied Gromov Wasserstein optimal transport (GWOT), an unsupervised method requiring no prespecified stimulus experience correspondence to compare toddlers, preschool children, and adults. Preschoolers' and adults' group-averaged structures perfectly aligned, whereas toddlers' structure did not fully align with either older group. However, removing specific colours, particularly those with relatively late acquired linguistic boundaries, such as light blue-restored near-perfect alignment. Moreover, toddlers with greater colour-word knowledge showed closer correspondence with the adult similarity structure. These findings suggest that the global relational geometry of colour experience is largely established by toddlerhood, with limited local differences linked to colour-language acquisition.

The development of speech in human children is a protracted process that depends on social experience. From early life, young children produce vocalizations in the presence of others, which affords unique opportunities for feedback about how to communicate successfully. However, for feedback to happen, young childrens speech needs to effect change in the brains of their caregivers. Using dual-brain functional near-infrared spectroscopy (fNIRS) to measure real-time communication between caregivers and their 2- to 3-year-old children (n = 56), we found that children's vocalizations selectively modulated caregivers' brain activity. Parents' brains showed a rapid response to children's production of speech that was communicatively advanced (multiword utterances) vs. less advanced (babble). The findings imply that if part of learning to talk is figuring out how to get your communication partner to listen, then early conversations likely present continuous opportunities for feedback that guide children toward advances in spoken language.

Spatial-numerical association reflects an internal "mental number line" where numerosities are mapped from left to right in space. While evidence from 8- to 9-month-old human infants suggests a privileged link between number and space, these findings do not definitively establish whether discrete numerosity or continuous quantity is the primary driver of spatialization due to the relatively extensive postnatal experience. Using domestic chicks (Gallus gallus), a model testable with minimal postnatal experience, we investigated precocial predispositions to map both discrete numerosities and continuous quantity (physical size) onto space. In Experiment 1, we replicated spatial-numerical association: chicks associated relatively smaller numerosities with the left hemispace and larger ones with the right hemispace. In Experiment 2, however, spatial-quantity association for physical size was asymmetric: chicks showed a rightward preference for smaller sizes and no congruent small-left/large-right mapping. Together with infant data, these findings indicate that a generalized and congruent spatial-magnitude association does not emerge at the earliest stages of development, and challenge accounts positing that spatial mappings for continuous magnitudes precede and underpin the spatial organization of number.

Infants actively shape their experience through self-generated movement. They need to move their head efficiently to explore and interact with their environment and to hold their head still to sustain attention. Controlled laboratory studies have documented the importance of head movements in orienting and stabilizing infant visual attention, but little is known about how head control develops as infants go about daily life, the setting in which development actually unfolds. We analyzed 383 hours of egocentric video collected from 88 infants aged 3 weeks to 29 months using head-mounted cameras in infants homes. Using a visual-odometry algorithm, we quantified rotational magnitude, the size of head movements; and rotational efficiency, the directional coherence of head movements. Head-rotation magnitude increased across the first year, and rotational efficiency improved throughout development.

Developmental dyslexia is associated with impaired cortical tracking of continuous speech and difficulties in perceiving within-word prosodic structure in children and adults. For adults and continuous speech, both low-frequency delta- and theta-band impairments and high-frequency gamma- and beta-band differences are found. To date, perceptual difficulties with intra-word prosody have not been studied in direct relation to neural speech encoding. Here neurotypical adults and adults with dyslexia listened to multisyllabic words. EEG was recorded, and cortical encoding was quantified using temporal response function (TRF) modelling. Four speech representations were explored: lexical stress pattern (intra-word prosodic prominence), the low-frequency speech envelope, word onsets and syllable onsets. Adults with dyslexia showed significantly reduced encoding of intra-word prosodic prominence (delta band) and of the speech envelope (delta and theta bands). In contrast, encoding of word and syllable onsets was preserved. Pinpointing delta-band cortical tracking as central to encoding intra-word prosodic prominence opens new avenues for research.

Background: Infants with extremely low birth weight (ELBW) are at high risk for neurodevelopmental impairment, but the relationship between cerebellar structure and later developmental outcome remains incompletely defined. Methods: In this retrospective single-center study, we examined total cerebellar volume on clinically acquired brain magnetic resonance imaging (MRI) in ELBW infants while accounting for postmenstrual age (PMA) at imaging. Results: Of 65 infants screened, 42 were included. Mean gestational age at birth was 25.54 {+/-} 1.68 weeks, mean birth weight was 733.2 {+/-} 118.7 g, and mean PMA at MRI was 43.02 {+/-} 6.53 weeks (range, 31.57--68.00). Mean cerebellar volume was 22.17 {+/-} 9.63 cm. Independently adjudicated developmental outcomes comprised normal development in 16 infants, isolated or specific impairment in 12, and moderate/severe impairment in 14. Unadjusted cerebellar volumes did not differ across developmental groups (P = 0.490) or qualitative MRI categories (P = 0.875). However, the PMA-by-developmental-category interaction was significant (P = 0.002), with estimated cross-sectional slopes of 1.72, 1.56, and 0.39 cm per week, respectively. The interaction remained significant within 36--46 weeks PMA (n = 29; P = 0.011) and after adjustment for small-for-gestational-age (SGA) status. Sensitivity analyses indicated uncertainty in the stability of the interaction. Conclusions: These findings suggest that age-informed cerebellar volumetric patterns may provide developmental information not evident from average volumes alone and support prospective validation with standardized imaging and developmental assessments. As a result, cerebellar volumes obtained early in life may hold prognostic information for ELBW infants.

The Visual Word Form Area (VWFA), located in ventral occipitotemporal cortex, plays a critical role in skilled reading. Researchers have theorized that the VWFA develops in its specific anatomical location due to the convergence of major white matter tracts and proximity to functionally similar regions. This suggests that precise anatomical positioning may be crucial for optimal VWFA function. Previous research has identified several functional differences in this region between typical and struggling readers (i.e. dyslexia): struggling readers show weaker text-selective responses and often exhibit a smaller or even absent VWFA. However, it remains unexplored whether the precise anatomical location of this region also differs between typical and struggling readers. We tested whether VWFA anatomy differs between children with and without dyslexia (N=87). Participants completed a functional localizer, which we used to manually define the VWFA in each individuals native anatomy. We examined whether: (1) VWFA anatomical location relates to reading ability, (2) children with dyslexia show greater variability in VWFA location compared to typical readers, and (3) VWFA location with respect to white matter tracts relates to reading ability. Results reveal that, despite being smaller in children with dyslexia, there is no relationship between VWFA location and reading ability. Specifically, individual VWFA location relative to anatomy, relative to others VWFAs, and relative to white matter tracts, is not related to reading ability. These findings suggest that while the VWFAs general anatomy may be facilitated by development, its precise location remains stable and unrelated to reading proficiency.

Exploration is fundamental to how children learn about the world. To explore a new environment comprehensively, a child must navigate without getting lost while simultaneously attending to salient information along the way. Both abilities improve across childhood, yet most studies examine them in isolation, often in constrained spaces with limited sensory complexity. Here, we asked 7- to 14-year-old children (N=42) and young adults (18-22; N=42) to freely explore a large furniture store in immersive virtual reality, which contained many objects and attention-capturing multisensory events. Surprisingly, despite traveling comparable distances, children explored less - they covered less spatial area and examined fewer unique objects than adults. Fine-grained analyses of their behaviors showed that the reduction in exploration was due to children spending more time backtracking and children taking longer to adapt to salient multisensory objects, which were uncorrelated across individuals after controlling for age and independently predicted exploration. However, only backtracking duration predicted success in a subsequent search task, demonstrating a link between navigational success during exploration and the quality of learned spatial representations for later use. Together, the results demonstrate that children explore less comprehensively than adults in large-scale spaces because they are susceptible to getting lost and perseverating on salient events nested within a large environment, but that these behaviors change with age. This suggests that while children are widely considered to be curious explorers within local environments, their ability to do so within larger environments is shaped by the maturation of cognitive systems that integrate experiences over complex contexts.

Sensorimotor synchronization, the ability to align motor behaviour with the temporal structure of external stimuli, is thought to emerge gradually during development, but its origins remain unclear. Here, we investigated whether newborns can adapt their sucking behaviour and synchronise it to the temporal structure of auditory stimuli within the first days of life. Forty-one healthy full-term newborns (24-72 hours old) were exposed to two three-minute auditory streams differing in temporal structure: a highly structured stream with a stable temporal pattern and a highly variant stream with greater temporal variability, while their non-nutritive sucking (NNS) was continuously recorded. We assessed changes in NNS frequency and pressure and quantified NNS-sound coupling using magnitude-squared coherence at frequencies distinctive to each auditory stream. Structured stimulation promoted a more organised NNS, with more suck bursts than the variant stream, and increased sucking vigour, with a transiently higher suck peak rate during the first minute relative to the variant stream and greater suck pressure relative to silence. Coherence analyses revealed that coherence was selectively higher at the frequencies distinctive to each auditory stream, both for the structured and the highly variant stimulus. These findings show that, within hours of birth, NNS behaviour can selectively align with stimulus-specific temporal regularities, even when these are weakly predictable and lack a dominant periodicity. This early capacity to extract temporal structure and coordinate motor behaviour may provide a foundation for the subsequent development of sensorimotor synchronisation.

Second language (L2) processing engages both language-specific and domain-general control systems, yet how these systems vary with L2 proficiency remains unclear. We used functional magnetic resonance imaging (fMRI) to examine neural activity during L2 English processing in Korean-English (K-E) bilinguals across three proficiency levels (beginner, intermediate, advanced). Participants performed rhyme and spelling judgement tasks manipulating orthographic-phonological conflict. Behaviourally, conflict conditions reduced accuracy, with proficiency effects observed selectively in the rhyme task. fMRI results showed that conflict processing recruited frontoparietal control regions, including inferior frontal and parietal cortices, accompanied by deactivation in default mode network regions. Critically, proficiency-related effects differed by task. During rhyme judgement, advanced bilinguals showed greater activation in the left supramarginal gyrus (SMG) and cerebellum, whereas intermediate bilinguals exhibited greater recruitment of the left middle orbital gyrus and dorsomedial prefrontal cortex. During spelling judgement, advanced bilinguals showed greater thalamic activation alongside greater deactivation of the right dorsolateral prefrontal cortex. Activity in the left SMG and cerebellum was positively associated with L2 reading score, and cerebellar activity was also associated with rhyme-task performance, whereas right DLPFC activity was negatively associated with the scores. These findings suggest that increasing L2 proficiency is associated less with altered recruitment of core reading regions than with task-specific shifts in the balance between phonological-specialized, subcortical attentional, and domain-general control systems supporting L2 processing.

Background: The subplate is a transient fetal brain compartment that provides an early foundation for downstream cerebral development. Congenital heart disease (CHD) alters fetal circulation and cerebral substrate delivery, but its impact on subplate development and whether resulting alterations relate to later neurodevelopmental outcomes remain unclear. Methods: In this retrospective observational cohort study, We used fetal MRI to quantify whole-brain, lobar, and regional (17 bilateral cortical regions) subplate volume and thickness to evaluate group differences between 76 fetuses with CHD and 62 typically developing (TD) fetuses scanned between 21-32 weeks of gestation, and estimated individualized deviations from TD developmental trajectories. Associations with fetal hemodynamic indices (substrate delivery score, cerebroplacental ratio [CPR]) and two-year neurodevelopmental outcomes (Bayley Scales of Infant and Toddler Development, N=46 CHD, N=37 TD) were explored. Results: Whole-brain subplate volume was lower in CHD, corresponding to a 5.7% reduction relative to age- and sex-expected values (p=0.003), but this difference was substantially attenuated after accounting for global brain volume (p=0.090). In contrast, regional analyses identified persistent spatially structured deviations beyond global scaling, most consistently involving posterior parietal, occipital and temporal regions, with a left-hemisphere bias in subplate thickness. Normative modelling demonstrated bidirectional regional deviations and increased inter-individual variability in CHD, with extreme subplate volume deviations enriched across 73% of cortical regions (p=0.009). Higher CPR was associated with lower SP thickness deviations, with the association strengthening after accounting for cerebral substrate delivery (p=0.010), although these analyses were exploratory. In CHD fetuses with postnatal follow-up, prenatal subplate deviations showed modest associations with neurodevelopmental outcomes, with right precuneus subplate thickness associated with receptive ({beta}=-11.87, q=0.017) and expressive ({beta}=-14.50, q=0.039) communication on the Bayley, after correction for multiple comparisons. Conclusions: Fetal subplate alterations in CHD are dominated by global reductions in brain growth but also include spatially heterogeneous and individually variable regional deviations beyond global scaling. Exploratory associations with fetal hemodynamics and postnatal neurodevelopment provide hypotheses for future studies investigating the developmental significance of these prenatal alterations.