Human infants show tremendous diversity in how they perceive and modulate stimulation from their surroundings. A groundbreaking investigation published in the Journal of Child Psychology and Psychiatry sheds crucial light on sensory processing in infancy. The investigators evaluated how distinct sensory modalities and response styles emerge at five months of age. Furthermore, they explored how these early profiles predict autistic traits at 36 months. Sensory atypicalities represent core features of autism spectrum disorder, yet clinicians previously lacked clarity regarding their earliest etiological origins. Because brain circuits develop dynamically during the first year of life, understanding early sensory profiles offers profound neurodevelopmental insight. Consequently, this cohort study disentangles the complex interplay between heritable biology and environmental factors during early infancy. The study also reinforces the importance of structured developmental surveillance across routine pediatric practice.

Understanding Sensory Processing in Infancy and Neurodevelopment

Sensory processing involves reception, organization, and behavioral modulation of environmental inputs. During typical development, neural pathways sculpt through early sensorimotor interactions with primary caregivers and physical objects. However, infants display marked variations in their sensory thresholds and behavioral reactivity. Sensory processing in infancy encompasses distinct behavioral phenotypes, including sensation seeking, sensation avoiding, sensory sensitivity, and low registration. In sensation seeking, an infant vigorously pursues intense sensory experiences. Conversely, sensation avoiding manifests as distress or active withdrawal from everyday auditory, visual, or tactile cues. Sensory sensitivity involves heightened reactivity without overt avoidance, whereas low registration reflects blunted responsiveness to incoming stimuli. Consequently, researchers have long sought to understand whether these response styles share a single neurodevelopmental origin or reflect independent mechanisms. Clarifying this structural architecture provides essential insights into early developmental cascades and neurodivergent trajectories.

Twin Study Methodology: Decoupling Genes and Environment

To untangle the underlying origins of sensory differences, the authors leveraged data from the BabyTwins Study Sweden. Specifically, the cohort comprised 285 same-sex twin pairs evaluated at five months of age. The sample included 158 monozygotic pairs and 127 dizygotic pairs. Researchers administered the Infant/Toddler Sensory Profile to primary caregivers to measure multi-domain responses. They assessed individual variability across four sensory quadrants and multiple sensory modalities. Subsequently, the researchers employed exploratory factor analysis, generalised estimating equations, and multivariate twin modeling. These statistical models systematically parsed phenotypic variance into additive genetic effects, shared family environment, and unique environmental factors. In addition, when the children reached 36 months of age, parents completed the Quantitative Checklist for Autism in Toddlers. Therefore, the longitudinal design enabled robust tracking from early infancy into toddlerhood.

Separable Genetic and Environmental Architecture of Sensory Dimensions

The investigation demonstrated clear phenotypic and etiological separability across all measured sensory dimensions. Rather than reflecting a singular regulatory axis, each sensory profile demonstrated unique genetic and environmental contributions. Sensation seeking, sensation avoiding, sensory sensitivity, and low registration each exhibited substantial additive genetic variation. Moreover, environmental factors shared within families contributed meaningfully to these emerging traits, although to a lesser degree than genetics. Modality-specific analyses revealed parallel patterns across tactile, visual, auditory, and vestibular domains. Genetic influences showed pronounced domain specificity, indicating that distinct biological networks regulate different sensory faculties. In contrast, shared environmental influences operated more broadly across multiple modalities. Thus, parental handling, feeding habits, and domestic physical spaces shape sensory adaptation through generalized environmental mechanisms.

Early Tactile Reactivity and Longitudinal Autistic Trait Emergence

The longitudinal follow-up provided vital clues regarding the emergence of autistic behavioral traits in toddlerhood. Specifically, heightened sensory sensitivity, elevated sensation avoiding, and pronounced low registration at five months significantly predicted higher autistic traits at 36 months. However, sensation seeking did not exhibit a statistically significant association with later autistic scores. Modality analyses revealed that atypical tactile behaviors showed the strongest predictive relationship with subsequent toddlerhood traits. For example, infants who demonstrated distress during diaper changes, feeding, or skin-to-skin touch later exhibited more autistic traits. Tactile processing serves as a fundamental foundation for early dyadic bonding and social communicative interaction. Consequently, tactile disruptions may alter early relational engagements, compounding downstream socio-communicative divergence over developmental time.

Clinical Implications for Pediatric Practice and Early Surveillance

These findings hold meaningful practical value for pediatricians, developmental pediatricians, and child psychiatrists. Traditionally, clinical teams have grouped sensory anomalies together under broad developmental labels. However, this study demonstrates that clinicians must evaluate sensory dimensions independently during physical assessments. Pediatricians should deliberately enquire about parental experiences regarding infant comfort during handling, bathing, and feeding. When parents describe marked tactile defensiveness or poor environmental registration, clinicians should monitor development closely. Moreover, because shared environmental factors meaningfully influence sensory modulation, clinicians can offer timely environmental guidance. Sensory adjustments at home, such as gradual tactile habituation and supportive soothing routines, may mitigate persistent infant distress. Consequently, early developmental mapping empowers clinicians to implement individualized, neuro-affirming monitoring strategies long before full behavioral syndromes solidify.

What did the study discover about early sensory processing?

The study discovered that sensory processing dimensions in infancy reflect distinct phenotypic and etiological mechanisms. Rather than operating as a unitary construct, dimensions such as sensation seeking, sensation avoiding, sensitivity, and low registration arise from separable additive genetic factors alongside meaningful shared family environmental influences.

How do specific infant sensory profiles relate to autistic traits?

Elevated sensory sensitivity, sensation avoiding, and low registration at five months significantly predicted higher autistic traits at 36 months. In particular, tactile-related atypicalities exhibited the strongest longitudinal connection. Conversely, infant sensation seeking showed no statistically significant relationship with toddlerhood autistic traits.

Why are tactile behaviors especially critical during early development?

Tactile processing underpins early caregiver interactions, somatic regulation, and attachment formation. When infants experience tactile hypersensitivity or aversion during routine handling, dyadic communication may become disrupted. Consequently, atypical tactile reactivity can initiate developmental cascades that influence emergent socio-communicative skills and behavioral adaptation.

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References

Bussu G et al. Different sensory dimensions in infancy are associated with separable etiological influences and with autistic traits in toddlerhood. J Child Psychol Psychiatry. 2025 Aug. doi: 10.1111/jcpp.14143. PMID: 40035145.

Baranek GT, David FJ, Poe MD, Stone WL, Watson LR. Sensory Experiences Questionnaire: discriminating sensory features in young children with autism, developmental delays, and typical development. J Child Psychol Psychiatry. 2006;47(6):591-601.

Dunn W. The sensations of everyday life: empirical, theoretical, and practical considerations. Am J Occup Ther. 2001;55(6):608-620.