A Child’s Temperament May Help Explain Why Autism Looks So Different from One Person to the Next
Autism is often described through shared diagnostic features, including differences in social communication, repetitive behaviors and sensory responses. Yet the spectrum is marked by striking variability: two autistic children can have very different abilities, challenges and everyday experiences. A new study of 121 preschool children suggests that part of this variation may be linked to the interaction between temperament—the biologically influenced way children react and regulate themselves—and sensory processing. The research found that autistic children had substantially lower “effortful control” than non-autistic children, while greater sensory discomfort was associated with more pronounced characteristics of autism. Together, effortful control and sensory discomfort explained nearly a quarter of the variation in autism-related characteristics among the autistic children studied. The findings do not suggest that temperament causes autism, but they point to regulatory and sensory processes that may influence how autism is expressed in early childhood.
The study, conducted by researchers in Québec and Türkiye, included 66 autistic preschoolers and 55 non-autistic children between 1.57 and 7.59 years old. The autistic group included children with an official diagnosis or children undergoing diagnostic assessment who also had an autistic parent or older sibling. The comparison group included children without autism or other developmental conditions and excluded those with an autistic close family member. The autistic participants were, on average, slightly older than the non-autistic children, had a higher proportion of boys and came from households with somewhat lower reported incomes. Because these factors can influence developmental and behavioral measures, the researchers statistically controlled for age and family income when comparing temperament. Data were collected between 2020 and 2023 as part of the Maman S’adapte longitudinal project, much of it during the COVID-19 pandemic, and the timing of data collection was also considered in the analyses.
To measure temperament, the researchers used the Children’s Behavior Questionnaire, a parent-report instrument based on Rothbart’s model of early personality and self-regulation. The questionnaire organizes children’s behavior into three broad dimensions. Surgency, or extraversion, captures activity, enthusiasm, laughter, intense enjoyment and relative lack of shyness. Negative affectivity includes fear, sadness, discomfort and the intensity or persistence of distress. Effortful control refers to the capacity to focus and shift attention, inhibit an inappropriate response, regulate behavior and tolerate low-intensity activities. These abilities depend partly on executive attention systems: a child must notice competing stimuli, select a response and suppress impulses while maintaining a goal. In practical terms, effortful control is involved when a child waits for a turn, moves from one activity to another or calms down enough to follow instructions.
After accounting for age and household income, the autistic and non-autistic groups did not differ significantly in negative affectivity or surgency. This result contrasts with some earlier studies that reported greater negative emotionality and lower social enthusiasm among autistic children. The researchers found that these apparent differences can shift depending on the characteristics of the comparison groups and the variables included in the analysis. In this sample, age was related to negative affectivity, and omitting the covariates produced a modest group difference in which autistic children had higher scores. The clearest temperament difference involved effortful control. Adjusted scores averaged 5.52 in the non-autistic group and 4.30 in the autistic group, producing a large statistical effect. Older children and children from higher-income households also tended to have higher effortful-control scores, emphasizing why developmental and social context matter when interpreting behavioral assessments.
Sensory processing was assessed with the Short Sensory Profile, a 38-item questionnaire covering tactile sensitivity, taste and smell, movement, sensation seeking or under-responsiveness, auditory filtering, energy levels and visual or auditory sensitivity. Lower total scores indicate greater sensory discomfort. The instrument classifies children as showing typical performance, a probable difference or a definite difference in sensory responses. In the study, 52 of the autistic children were in the definite-difference category, six were in the probable-difference category and one fell within the typical range. By comparison, 38 non-autistic children had typical scores, 12 showed a probable difference and three showed a definite difference. These results reinforce that sensory differences are common in autism, but they also show that unusual sensory responses are not exclusive to autistic children. Sensory processing involves detecting, filtering and integrating information from the environment, as well as generating an adaptive behavioral response; disruption at any of these stages can make ordinary sounds, textures, movement or visual input unusually uncomfortable or difficult to ignore.
Across both groups, higher negative affectivity was associated with lower Short Sensory Profile scores, meaning greater sensory discomfort. The relationship remained similar in autistic and non-autistic children rather than being significantly stronger in one group. A child who is more emotionally reactive may therefore also be more likely to experience everyday sensory input as overwhelming, or sensory discomfort may intensify distress and make emotional recovery harder. The study cannot determine which direction the relationship runs. Temperament and sensory processing may influence each other over development, and the two measures also overlap conceptually: both involve reactivity, attention and regulation. Nevertheless, negative affectivity did not account for all the variation in sensory scores, suggesting that emotional reactivity and sensory discomfort are related but distinct characteristics. Contrary to the researchers’ predictions, surgency and effortful control were not significantly associated with sensory discomfort in the combined analysis.
Within the autistic group, the researchers then examined whether temperament and sensory discomfort were related to scores on the Childhood Autism Rating Scale, Second Edition. The scale rates the intensity and duration of behaviors across 15 areas, with higher scores indicating more pronounced autism-related characteristics. In a regression model that included effortful control and sensory discomfort, the two measures together explained 23 percent of the variation in CARS scores. Lower effortful control was associated with higher autism-characteristic scores, as was greater sensory discomfort. When age and family income were included as additional variables, the full model explained 25 percent of the variance, although sensory discomfort was the only significant predictor in that version. The statistical relationships are correlational, not evidence that poor self-regulation or sensory differences produce autism. Instead, they suggest that children with similar diagnoses may show different levels of observable difficulty partly because they differ in how they regulate attention and behavior and how their nervous systems respond to sensory input.
The findings could influence early assessment and support without turning temperament into another diagnostic test. A child with high sensory discomfort may struggle in a noisy classroom, reject certain clothing or foods, or become distressed during transitions; a child with low effortful control may find it especially difficult to shift attention, inhibit a response or recover from frustration. Recognizing these patterns could help clinicians and educators tailor environments, reduce overwhelming stimuli and teach regulation strategies. Families might also benefit from understanding that behavior interpreted as oppositional or inattentive can reflect a mismatch between a child’s sensory demands and regulatory capacity. The study has important limits: its sample was relatively small and recruited for a broader project rather than powered in advance for every analysis; mothers completed all questionnaires; diagnostic information relied partly on parental reports during pandemic restrictions; and the CARS assessment was based on structured telephone interviews rather than direct observation. Some children were younger than the age for which the Children’s Behavior Questionnaire is typically recommended, and autistic participants included co-occurring ADHD and epilepsy. Larger, clinically confirmed and longitudinal studies will be needed to determine how sensory processing and effortful control change over time and how much they improve the usefulness of individualized early intervention.
