“Making Sense of It All.” Sensory-Processing Sensitivity, Negative Affect, Extraversion and Effortful Control in Children with and without ASD

Background: Recently, hypo- and hypersensitivity to sensory stimuli became part of the diagnostic criteria for autism spectrum disorder (ASD) in DSM-5. Further, previous research in temperament has shown that children with ASD show more Negative Affect, less Extraversion and less Effortful Control (inhibition control and attentional focus). In addition, regardless of clinical diagnosis, children with high levels of temperamental sensory-processing sensitivity (SPS) may exhibit ASD-like behaviour, such as social withdrawal and strong adherence to routines. This may lead to diagnostic difficulties.

Objectives: The first purpose of the present exploratory study was to further examine the characteristics of the temperamental construct of SPS in children. Second, relationships and differences between ASD-symptoms, characteristics of SPS and the other temperamental constructs were explored.

Methods: Data from 409 children (3-16 years) with and without a clinical diagnosis were collected through an online survey. Parents reported on ASD symptoms (SCQ, SRS), SPS (Highly Sensitive Person Scale; HSPS) and other temperamental constructs (CBQ, TMCQ, EATQ-R).
First, the factor structure of the HSPS was explored. Second, group differences between ASD-symptoms, SPS, Negative Affect, Extraversion and Effortful Control were examined between children with ASD (N=37), highly sensitive children (HSC; N=60) and a non-clinical control group (non-HSC; N=259).

Results: Factor analysis demonstrated a two-component structure of the HSPS. The first component consisted of Overstimulation, Emotional intensity and Sensory sensitivity, reflecting Overreaction to stimuli. The second component reflected Depth of processing.
Regarding the group comparison on the HSPS, children with ASD scored only higher on the first component (Overreaction to stimuli) compared to children in the control group.
Further, HSC scored higher on some typical characteristics of ASD (e.g., repetitive and stereotyped behavior and a restricted social cognition and motivation) compared to non-HSC. However, children with ASD still scored higher on most typical ASD-symptoms compared to HSC. Difficulties in distinguishing HSC and children with ASD were only seen for social motivation.
In accordance to previous research, children with ASD showed more Negative Affect, less Extraversion and less Effortful Control compared to children from the control group.
HSC exhibited more Negative Affect and less Extraversion compared to non-HSC. They did not differ in this from children with ASD. However, HSC showed more Effortful Control compared to children with ASD and control children. 

Conclusions: In contrast to previous findings in adults that the HSPS measures a unidimensional construct, our data support a two-factor structure in children. Only the first factor (Overreaction to stimuli) was associated with ASD, which implies that high scores on this component could be an indication of ASD.
Overall, the present study offers suggestions for differentiating children with a highly sensitive temperament from children with ASD, who could also react in a hypersensitive way to sensory stimuli. Despite similarities in repetitive and stereotyped behaviour, restricted social motivation, high Negative Affect and low Extraversion, the two groups can be discriminated on typical social and communicative ASD-symptoms and temperamental Effortful Control.