Relationship between social anxiety and separation anxiety symptoms with insistence on sameness with the mediating role of sensory hypersensitivity

Abstract

Background

Autism spectrum disorder (ASD) is characterized by impairments in social communication and interaction, restricted and repetitive patterns of behavior, and sensory processing abnormalities. These core features are often accompanied by comorbid anxiety disorders. However, the sequence and mechanisms of these associations warrant further investigation. Therefore, the aim of this study was to examine the relationship of social anxiety and separation anxiety on insistence on sameness, mediated by sensory hypersensitivity.

Methods

This was a cross-sectional study based on caregiver reports of 247 children, aged 7 ̶ 11 years. The parents completed the Autism Quotient-Children’s Version (AQ-C), the Repetitive Behavior Questionnaire-2 (RBQ-2), the Sensory Profile 2 (SP2), and the Spence Children’s Anxiety Scale-Parent Version (SCAS-P).

Results

The path analysis revealed a significant indirect effect of social anxiety and separation anxiety on insistence on sameness via sensory hypersensitivity (p ≤ 0.05). However, neither social anxiety nor separation anxiety had a significant direct effect on insistence on sameness (p = 0.108 and p = 0.342, respectively).

Conclusions

Based on the results, the mediated association of sensory hypersensitivity with the relationship between social anxiety, separation anxiety, and insistence on sameness was observed. The article discusses the theoretical explanations and implications of the results, as well as various manifestations of anxiety symptoms in children with ASD.

Background

Autism spectrum disorder (ASD) is characterized by persistent deficits in communication and social interaction, along with restricted and repetitive patterns of behavior, interests, or activities. These symptoms are present from early childhood, but their onset and severity can vary based on individual and environmental factors such as developmental level, age, and gender. This heterogeneity is reflected in the term “spectrum” in the disorder’s name [1].

A key aspect of ASD is insistence on sameness, which includes a strong preference for routines and resistance to change. These ritualistic behaviors are developmentally appropriate for children aged 2 to 4 but can become problematic when they persist beyond this age range [10].

This persistence is particularly evident during periods of transition, where insistence on sameness is often linked to fears and anxieties, such as fear of the dark or separation anxiety. These behaviors are hypothesized to serve as a primitive form of self-regulation, reducing fear and anxiety by constraining the unpredictable environment. Over time, these behaviors are typically replaced by more mature and flexible forms of self-regulation that effectively modulate distress and anxiety [42]. In individuals with ASD, insistence on sameness behaviors is relatively stable over time. However, research has shown that these behaviors can persist beyond the period in which they are adaptive and become more pronounced, serving as a coping mechanism for managing anxiety and sensory overload. This persistence can have a detrimental impact on development, particularly on the persistence of anxiety [43]. For example, Baribeau et al. (2022) found that high levels of insistence on sameness in preschoolers with ASD were associated with elevated anxiety symptoms in later childhood [4]. Similarly, Stock and Lucyshyn (2023) discussed how violations of sameness can lead to problem behaviors, emphasizing the need for individualized behavior support plans [37].

In addition to their role in self-regulation, these behaviors can also become habitual. Reward-driven behaviors typically begin as goal-directed actions that are controlled by outcome anticipation. However, these behaviors can become stimulus-driven habits under certain conditions that are not controlled by the expectation of outcomes. Consequent to the consistent replication of behaviors yielding identical outcomes, the focus may shift away from the consequences of the actions. Subsequently, the actions evolve into goal-directed, automatized, and habitual behaviors, which are regulated by antecedent stimuli [38].

The interaction between the core symptoms of autism and social anxiety is complex and often poses challenges for clinicians. Although autism and social anxiety are distinct disorders, shared symptoms, including impairments in social interaction, such as decreased eye contact, can lead to misinterpretation of symptoms [39]. Deficits in typical social skills in ASD can contribute to the development of social anxiety by affecting factors such as social motivation and behavioral inhibition and negatively impact social experiences [30]. In addition, some theories suggest that in ASD, stereotyped and repetitive behaviors or conversations, such as hand gestures or stereotyped body movements, can lead to stigma, increased risk of social adversity, bullying, and victimization, which in turn contribute to social withdrawal and isolation [26, 33].

This relationship between insistence on sameness and anxiety shows how these behaviors can serve as coping mechanisms. Anxiety in ASD often manifests through insistence on the same behaviors as a way to manage uncertainty and stress [42]. It can also be associated with a variety of sources, including social communication disorders and sensory hypersensitivity. Incomplete understanding of others’ intentions, communications, and expectations may make the social world and its demands unpredictable, chaotic, and ultimately anxiety-provoking. Conversely, sensory hypersensitivity (such as loud noises), which is common in people with autism, may cause aversion and subsequent anxiety reactions to situations that are not normally anxiety-provoking (such as the sound of a balloon popping or a vacuum cleaner) [28].

The presence of conflicting symptoms of anxiety, such as fear of change or unusual phobias, possibly related to unusual sensory experiences, complicates the diagnosis of anxiety in these children. In fact, it has been estimated that up to 46% of these children show anxiety symptoms that do not correspond to nomenclature systems such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) [17, 24].

Studies, including Boelen et al.‘s (2014) study in a non-autistic population and Rodgers et al.‘s (2012) study in an autistic population, have shown a relationship between separation anxiety and insistence on sameness [7, 31]. In addition, Black et al. (2017) examined the relationship between separation anxiety and sensory sensitivity and found that hypersensitivity in autism strongly mediated the relationship between separation anxiety and insistence on sameness.

A study by Green et al. (2015) found that children with ASD showed greater activation in the amygdala and primary sensory areas in response to mildly aversive sensory stimuli. This overreaction can make social environments challenging for people with ASD. Social situations often involve unpredictable sensory input, such as loud noises, bright lights, or unexpected touches, which can trigger intense anxiety reactions. This sensory hypersensitivity can lead to increased social anxiety, as individuals with ASD may find social interactions overwhelming and uncomfortable [13].

On the other hand, sensory processing disorders are a group of disorders that involve difficulties in regulating, modulating, integrating, organizing, and discriminating sensory input, such that the person cannot respond appropriately to the input and has problems in daily functioning and emotional-behavioral regulation. sensory hypersensitivity refers to excessively intense or prolonged behavioral reactions to environmental stimuli that are typically perceived as not unpleasant [15]. Many children with ASD have an atypical sensitivity to sensory stimulation, affecting several modalities (vision, audition, touch, smell, and taste). For example, some have low sensitivity to light, sound, temperature, or pain. They do not feel pain after falling, and some have high sensitivity to stimuli; for example, they cannot tolerate the material and texture of some clothes [29].

Currently, three possible theories have been proposed to account for the relationship between anxiety and sensory hypersensitivity: (a) sensory hypersensitivity is a consequence of anxiety, (b) anxiety is a consequence of sensory hypersensitivity, or (c) sensory hypersensitivity and anxiety are not causally related, but are associated through a common risk factor or diagnostic overlap [13].

A correlation between sensory sensitivity and insistence on sameness behaviors, such as behavioral rigidity and restricted interests, has been observed. It has also been suggested that insistence on sameness behaviors may serve as a coping strategy for managing sensory overload and anxiety. Therefore, sensory hypersensitivity may help explain the co-occurrence of anxiety and insistence on sameness behaviors [6, 13, 17,18,19].

Studies examining the relationships between sensory sensitivity, anxiety, and insistence on sameness behaviors have proposed different models. In the first model, sensory sensitivity (operationalized as sensory avoidance and sensory sensitivity) mediates the relationship between anxiety and insistence on sameness. This suggests that individuals with higher sensory sensitivity may experience increased anxiety, which in turn leads to greater insistence on sameness behaviors as a coping mechanism [19]. In contrast, the second model proposes that anxiety (along with intolerance of uncertainty) mediates the relationship between sensory sensitivity and insistence on sameness. This model implies that sensory sensitivity leads to heightened anxiety, which then manifests as insistence on sameness behaviors to reduce uncertainty and anxiety [45].

There is also conflicting evidence for a three-way relationship between sensory sensitivity, anxiety, and insistence on sameness in children with ASD. Some studies suggest that these factors interact in complex ways, with each influencing the others bidirectionally [6]. The conflicting evidence and different models tested in these studies highlight the complexity of autism spectrum disorder and the variability in how symptoms manifest. Understanding and examining these relationships can lead to the development of more personalized and effective interventions that address the specific needs of individuals with ASD.

By examining these models, our study aims to elucidate the mechanisms underlying these connections and help develop more effective treatment strategies. Therefore, the purpose of this research was to investigate the relationship between social anxiety and separation anxiety on the insistence on sameness with the mediation of sensory hypersensitivity.

Materials and methods

Participants and procedure

This cross-sectional study, conducted in 2023, recruited participants from children aged 7 to 11 years (first to fifth grades), attending girls’ and boys’ elementary schools in Shiraz city, in Iran. A random cluster sampling method was used to select 247 participants from the population. This study received approval from the Research Ethics Committee of University of Tabriz, and all study procedures were conducted in accordance with the ethical code IR.TABRIZU.REC.1402.117. Informed consent was obtained from all parents of the children who participated in the study. The study was conducted with the approval of the General Department of Education of Fars province. Among the five educational districts of Shiraz, district 3 was randomly chosen. Then, four elementary schools were randomly sampled from this district. A total of approximately 402 children were initially contacted through these class groups. Of these, 253 participants completed the study, yielding a response rate of 62.5%. However, 6 responses were excluded due to a high number of incomplete answers, resulting in a final sample size of 247 participants. The remaining individuals declined to complete the questionnaires, citing reasons such as time constraints, lack of interest, and the extensive length and number of questions. With the collaboration of the school administration, the questionnaires were distributed to the parents of children for girls and boys. The parents were instructed to complete the questionnaires online. Data were collected using the Autism Quotient-Children’s Version (AQ-C), the Repetitive Behavior Questionnaire-2 (RBQ-2), the Sensory Profile-2 (SP2), and the Spence Children’s Anxiety Scale-Parent Version (SCAS-P). The data were analyzed using IBM SPSS Statistics version 19 and AMOS version 24.

Measures

Autism-Spectrum Quotient (AQ)

the Autism-Spectrum Quotient- Children’s Version was developed by Cohen et al. (2008) to assess the subthreshold symptoms of ASD in typically developing children aged 4 to 11 years [2]. This scale consists of 50 items with a 4-point Likert scale that are completed by one of the child’s parents. The subscales of this measure are: social skills, attention switching, attention to detail, communication, and imagination. The total score ranges from 0 to 150, with higher scores indicating higher levels of general ASD behaviors. The reliability of this measure is 0.85 and Cronbach’s alpha is reported as 0.97 for the whole scale. Nejatisafa et al. (2003) reported the reliability of this measure as 0.82 and the Cronbach’s alpha for the internal consistency as 0.76 and for the total score as 0.79. The AQ-C data are analyzed as an indicator of symptom severity.

Repetitive Behavior Questionnaire-2 (RBQ-2)

The Repetitive Behavior Questionnaire-2 (RBQ-2; [16]), a 20-item questionnaire measured on a 3-point Likert scale was developed by Leekam et al. (2007) to examine the frequency and intensity of restricted and repetitive behaviors. In the study of Leekam et al. (2007), the inter-item correlation ranged from 0.44 to 0.73 and Cronbach’s alpha was 0.85. This questionnaire is answered by the caregiver and respondents rate the child’s behavior in the past month. A total score of restricted and repetitive behaviors is obtained by summing the scores of the items, ranging from 20 to 60. This questionnaire measures two factors: (a) motor/sensory behaviors and (b) preoccupation with inflexible, rigid, and restricted interests. The Cronbach’s alpha calculated in the present study was 0.86 for all items of the RBQ-2 and 0.76 for preoccupation with inflexible, rigid, and restricted interests.

Short Sensory Profile 2 (SSP2)

The Short Sensory Profile 2 (SSP2) is a shortened and revised version of the Sensory Profile (SP) questionnaire [10] that identifies how sensory processing problems affect the child’s participation in daily activities and was developed by McIntosh et al. (1999). This questionnaire contains 38 items organized into 7 subscales: tactile sensitivity (TAC; 7 items), taste/smell sensitivity (TSM; 4 items), movement sensitivity (MOV; 3 items), under-responsive/seeks sensation (USS; 7 items), auditory filtering (AFL; 6 items), low energy/weak (LEW; 6 items), and visual/auditory sensitivity (VAS; 5 items). All items are rated on a 1–5 Likert scale based on the frequency of the described behavior. The total score ranges from 38 to 190, where 155 to 190 indicates typical performance, 142 to 154 indicates probable difference in performance, and 38 to 141 indicates definite difference in performance [11]. The internal consistency of the subscales in this questionnaire is 0.70 to 0.90 and the inter-subscale correlation is between 0.25 and 0.75 [10]. In the study of McIntosh et al. (1999) they showed a validity higher than 0.95 in children with and without sensory processing problems [21]. The standardization of this questionnaire in Iran has shown a content validity of more than 0.90 and a suitable reliability of more than 0.90 [20].

Spence Children’s Anxiety Scale-Parent Version (SCAS-P)

The Spence Children’s Anxiety Scale-Parent Version (SCAS-P) was developed to assess symptoms of six different types of child anxiety in the general population: panic/agoraphobia, separation anxiety, social anxiety, physical injury fears, obsessive-compulsive disorder, and generalized anxiety. Symptoms are rated on a 4-point Likert scale and scores are calculated from the sum of items in each subscale and the sum of all items. The scores include a total raw score (from 0 to 114) and six subscale scores, with higher scores indicating greater severity of anxiety symptoms. A percentile scores greater than 84 for any subscale score or total SCAS score indicates clinically significant anxiety symptoms [36]. The individual subscales have shown good internal consistency (∝=0.87) and test-retest reliability (∝=0.82) with typically developing children [27]. Hefeshjani et al. (2021) reported Cronbach’s alpha coefficient for the whole scale as 0.93 and total reliability as 0.87 in Iran [14].

Statistical analysis

To maintain the quality of data collected online, the internal consistency, measured by Cronbach’s alpha, was assessed for each questionnaire. Within the present sample, high internal consistency was noted across each scale (the Repetitive Behavior Questionnaire-2; α = 0.85, the Sensory Profile 2; α = 0.92, and the Spence Children’s Anxiety Scale-Parent Version; α = 0.90). The data underwent a screening process to identify statistical outliers, which were then adjusted using the winsorization method. Subsequently, the data distributions were examined for normality using the Kalmogorov-Smirnov test. Multicollinearity was assessed by examining the Variance Inflation Factor (VIF) values, ensuring they were below the threshold of 5. Independence of residuals was checked using the Durbin-Watson statistic. The study used a path analysis method to examine the relationships between variables. We used an alpha value of 0.05 for most statistical tests to determine significance. For the Kolmogorov-Smirnov test, which we used to assess the normality of the data distributions, we applied a significance level of (p < 0.01). Fit indices, including the Chi-square test, Comparative Fit Index (CFI), Goodness of Fit Index (GFI), Normed Fit Index (NFI), and Root Mean Square Error of Approximation (RMSEA), were used to evaluate the fitness of the path analysis model. Decisions regarding the assumptions and results were based on these fit indices and the direct and indirect effect coefficients computed during the analysis. Detailed results of these fit indices are also provided in the results section.

Results

The study sample consisted of 247 children, of whom 96 (38.9%) were boys and 151 (61.1%) were girls. Tables 1 and 2 provide more information on demographic variables and study variables. The study examines relationships among the variables using the model presented in Fig. 1.

Table 1 Summary of the demographic characteristics

Table 2 The descriptive statistics of the studied variables (n = 247)

Hypersensitivity and insistence on sameness (I/S) were analyzed separately for their pairwise correlations with each other and with the two anxiety subtypes: social anxiety and separation anxiety. Hypersensitivity showed a negative correlation with I/S (r = -0.43, p < 0.01), as well as with social anxiety (r = -0.45, p < 0.01) and separation anxiety (r = -0.39, p < 0.01) (Table 3).

Table 3 Correlation between insistence on sameness, hypersensitivity, Social anxiety, and separation anxiety

The results of the Kolmogorov-Smirnov test for normality, using a significance level of 0.01, indicate that none of the variables significantly deviate from normality. Specifically, the p-value for Insistence on Sameness is 0.029, which is greater than 0.01, suggesting that its distribution does not significantly deviate from normality at this stringent level. Similarly, the p-values for Separation Anxiety (0.306), Social Anxiety (0.088), and Sensory Hypersensitivity (0.416) are all greater than 0.01, indicating that their distributions also do not significantly deviate from normality.

The Durbin-Watson statistic for the regression model was calculated to be 1.96. This value is close to the ideal value of 2, indicating that there is no significant autocorrelation in the residuals. Therefore, the assumption of independence of error terms is reasonably satisfied in this analysis.

Furthermore, The Variance Inflation Factor (VIF) values for Separation Anxiety, Social Anxiety, and Sensory Hypersensitivity were 1.46, 1.56, and 1.31, respectively. These VIF values are all below the commonly accepted threshold of 10, indicating that multicollinearity is not a concern in this model. Additionally, the Tolerance values for Separation Anxiety, Social Anxiety, and Sensory Hypersensitivity were 0.68, 0.64, and 0.76, respectively. These values are above the threshold of 0.1, further confirming that multicollinearity is not problematic in this analysis (Table 4).

Table 4 Multicollinearity among the variables

Table 5 represents the model fit indices for the structural model. The root mean square error of approximation (RMSEA) and the chi-square to degrees of freedom ratio (CMIN/DF) were within the optimal range (less than 0.03 and between 0 and 3, respectively). Moreover, the goodness of fit index (GFI), the comparative fit index (CFI), and the normed fit index (NFI) were all above the optimal value (more than 0.90). These results indicate that the structural model fits the data well and that the symptoms of separation anxiety and social anxiety can significantly account for the variance in insistence on sameness through sensory hypersensitivity as a mediator.

Table 5 The fit indices of the model

Table 6 reports the direct effect coefficients of the social anxiety, separation anxiety and sensory hypersensitivity on insistence on sameness. The results show that the standardized coefficient for separation anxiety (0.061, P = 0.342) and social anxiety (0.136, P = 0.108) were not significant. However, these variables have an indirect effect through sensory hypersensitivity with the effect coefficients of 0.080 (P = 0.005) and 0.168 (P = 0.001), respectively. Additionally, the total score of sensory hypersensitivity has a significant direct effect (− 0.063) on insistence on sameness (P < 0.001) (Table 7). It is important to note that higher scores on the SSP questionnaire indicate less hypersensitivity. Therefore, the negative standardized coefficient between insistence on sameness and sensory hypersensitivity suggests that as sensory hypersensitivity decreases (i.e., higher SSP scores), insistence on sameness increases. This relationship is similarly observed with anxiety.

Table 6 The direct effect coefficients

Table 7 Indirect effects of social anxiety and separation anxiety on insistence on sameness through sensory hypersensitivity

Fig. 1

Model designed for examination of the relations between the studied variables

Note: The figure presents the path coefficients for the mediation model. Most paths are statistically significant (p < 0.05), except for two indirect coefficients which are not significant. Detailed statistics, including standard errors and p-values, are provided in Table 6

Discussion

This study demonstrated that separation anxiety and social anxiety did not directly predict changes in insistence on sameness. This finding is consistent with the studies of Moore et al. (2021), Uljarević et al. (2017), and Gotham et al. (2013). Specifically, Moore et al. (2021) found that while anxiety was related to other behavioral symptoms in ASD, it did not directly influence insistence on sameness [23]. Similarly, Uljarević et al. (2017) argued that insistence on sameness and anxiety are not directly related but are associated with other factors such as cognitive flexibility and sensory processing [41]. Gotham et al. (2013) also reported a slight but significant relationship between anxiety and insistence on sameness, suggesting that these constructs function independently to some extent [12].

In contrast, our findings diverge from those of Baribeau et al. (2020), Kaylin et al. (2019), and Rodgers et al. (2012). Baribeau et al. (2020) reported a direct relationship between anxiety and insistence on sameness, suggesting that anxiety exacerbates repetitive behaviors in individuals with ASD [3]. Kaylin et al. (2019) found that anxiety, particularly social anxiety, was a significant predictor of insistence on sameness behaviors. Rodgers et al. (2012) also highlighted a strong link between anxiety and repetitive behaviors, indicating that anxiety directly influences the severity of these behaviors. Nonetheless, these factors are indirectly associated with sensory hypersensitivity.

Previous research has shown mixed results regarding the relationship between anxiety subscales and insistence on sameness. For example, some studies have shown that sensory sensitivity mediates the relationship between specific phobias and insistence on sameness, but not social anxiety [6]. This suggests that while certain types of anxiety are related to insistence on sameness through sensory processing issues, social anxiety, and separation anxiety may not directly influence insistence on sameness behaviors. Conversely, Kaylin et al. (2019) found that social anxiety is a significant predictor of insistence on sameness behaviors. This aligns with the findings of Briot et al. (2020), who reported that social anxiety contributes to impairments in social communication and social motivation in children and adolescents with ASD [8]. Additionally, Carpita et al. (2024) highlighted the overlap between social anxiety and autistic traits, suggesting that social anxiety may manifest differently in individuals with ASD [9]. These findings underscore the importance of considering social anxiety as a distinct subtype of anxiety in ASD research.

Anxiety in individuals with ASD may stem from difficulties in social communication, such as challenges in understanding social cues, maintaining conversations, and forming relationships, which can lead to increased stress and anxiety in social situations [6].

Anxiety disorders in ASD include typical and atypical manifestations such as fear of change or novelty, concern about narrow or specialized interests, and atypical phobias. The diversity of these manifestations and the overlap of many symptoms of anxiety and ASD create significant challenges for the identification and classification of anxiety symptoms in ASD. For example, anxiety expressions such as social withdrawal and ritualistic behaviors can superficially resemble the core social impairments of ASD, making the diagnosis of social anxiety difficult. Traits that are common in ASD may also influence the expression of social anxiety and separation anxiety symptoms. For example, individuals with ASD who are minimally verbal and have a concurrent intellectual disability may not report their internal state (e.g., worry) and instead express their anxiety through nonspecific behaviors (e.g., avoidance, disruptive behavior, tension). Additionally, social engagement is usually inherently fraught with risk due to potential exposure to internal physiological responses, such as erythema—typically experienced as facial flushing—which can trigger a cycle of avoidance and anxiety [25]. Similarly, ASD-related difficulties in recognizing, interpreting, and verbally reporting internal feelings and emotions may also alter the presentation of social anxiety and separation anxiety in verbally dominant individuals. Behaviors such as screaming, which may reflect anxiety in a nonverbal child or a child with limited emotion recognition, may also reflect learned behavior patterns aimed at escaping demands, gaining attention, or other instrumental goals unrelated to anxiety [28].

Other studies have shown that anxiety, in general, can exacerbate repetitive behaviors, but the specific pathways and mechanisms are unclear [34, 32]. Emphasizing that not all subtypes of anxiety have the same effect on insistence on sameness, our findings suggest that the relationship between anxiety and insistence on sameness in autism is complex and may depend on the type of anxiety experienced. This is consistent with the neurodevelopmental model of autism, which states that different symptoms and behaviors can have different underlying mechanisms. By showing that social anxiety and separation anxiety do not directly predict insistence on sameness, our study supports the idea that sensory sensitivity and other factors may play a more important role in mediating these relationships.

As with other psychiatric conditions, differentiating the symptoms of separation anxiety disorder from those of ASD can be challenging. Characteristics associated with ASD such as social difficulties, adherence to routines, and lower adaptive skills may complicate the diagnosis of separation anxiety in these individuals. For example, not participating in various events or games may indicate separation anxiety if it is due to worry about being separated from parents. Also, following specific bedtime routines that require parents to be close to the child throughout the night may indicate separation anxiety. The need to be accompanied by parents in daily life may reflect separation anxiety if it is due to fears related to separation anxiety (not wanting to be separated from parents), or it may reflect the need to be accompanied due to lower adaptive functioning skills. For example, a child may need help with bathing due to low adaptive skills associated with ASD, or may want a parent in the same room with him or her due to separation anxiety [44].

The relationship between anxiety and insistence on sameness is a complex and debated topic, and various studies have been conducted in this area. Some studies have shown that anxiety and insistence on sameness are two independent variables that do not have a direct effect on each other. For example, Bishop et al. (2013) concluded in a study that anxiety and insistence on sameness function as distinct constructs, each with a wide range of expression in children with ASD at different ages and cognitive levels [5]. Also, Uljarević et al. (2017) argue that insistence on sameness and anxiety are not directly related, but are associated with other factors such as cognitive flexibility, sensory processing, and social communication. Gotham et al. (2013) in a study showed that the variables of anxiety and insistence on sameness were slightly, but significantly, related to each other and to chronological age and verbal IQ. Also, anxiety was associated with other types of psychiatric and behavioral symptoms in ASD, such as irritability, attention problems, and aggression, while insistence on sameness was not. For this reason, they suggested that anxiety and insistence on sameness act as distinct constructs [12].

In this study, it was found that separation anxiety and social anxiety were related to insistence on sameness behaviors through the mediating factor of sensory hypersensitivity. This suggests that individuals with higher levels of sensory hypersensitivity may experience increased anxiety, which in turn leads to greater insistence on sameness as a coping mechanism. Specifically, the heightened sensory sensitivity exacerbates the anxiety associated with separation and social situations, driving individuals to seek consistency and predictability in their environment to manage their anxiety.

Although most studies have only examined relationships with overall anxiety scores, sensory hypersensitivity seems to be related to specific anxiety subtypes. Black et al. (2017) examined the relationship between sensory hypersensitivity and specific phobia, separation anxiety, and social anxiety, finding that sensory hypersensitivity was related to separation anxiety and specific phobia, but not to social anxiety. Similarly, Spain et al. (2018) noted that there is little evidence for a relationship between sensory hypersensitivity and social anxiety, which could instead be related to increased physiological arousal and differences in social skills [35]. McLennan (2019) found a positive correlation with anxiety in general, separation anxiety, and fear of physical harm. However, when controlling for ASD traits, they found that sensory hypersensitivity was associated with fear of physical harm and specific phobia, while hyposensitivity was associated with lower general anxiety and social anxiety. Additionally, research in non-ASD populations has shown that sensory hypersensitivity is associated with childhood rituals, and oral and tactile over-responsivity is associated with obsessive-compulsive symptoms in adults [22].

These findings contribute to the existing evidence base by highlighting the specific role of sensory hypersensitivity in mediating the relationship between anxiety subtypes and insistence on sameness. This underscores the importance of considering sensory processing issues in the assessment and treatment of anxiety in individuals with ASD. By clarifying these relationships, our study highlights the importance of addressing sensory processing issues in interventions for individuals with ASD. Interventions that target sensory hypersensitivity, such as sensory integration therapy or sensory processing interventions, may be particularly effective in reducing IS behaviors and managing anxiety.

Limitations

This study has several limitations that must be acknowledged. First, the sample was limited to 7- to 11-year-old students, which may not be representative of the broader population. Future studies should consider a larger and more diverse sample to increase generalizability. For example, our study did not include a clinical sample specifically composed of children with ASD, which limits the generalizability of our results and may not fully represent the same nuances of anxiety and impulsivity in clinically diagnosed ASD populations.

In addition, reliance on specific questionnaires may limit the scope of findings, and the use of a variety of valid instruments may help capture a wider range of symptoms and behaviors. In this study, data were collected using parent-reported questionnaires, which may cause bias due to subjective perceptions. It also did not consider cultural and contextual factors that may be associated with the relationship between variables, suggesting that future research should consider these factors to provide a more nuanced understanding.

Another limitation of this research is its cross-sectional design, which limits our ability to infer causality and direction between subgroups of anxiety and insistence on sameness. Longitudinal studies are needed to better understand how these variables influence each other over time. This helps clarify whether anxiety leads to increased insistence on sameness or whether the relationship is bidirectional.

Given the concern for selection bias, it is important to acknowledge that the lack of accurate data on the number of questionnaires distributed and potential non-response bias could affect the generalizability of our findings. Questionnaires were distributed online during school registration, and we estimate that approximately 402 students were contacted. Of these, 253 students completed the questionnaires, but 6 responses were unusable due to too many blank responses, resulting in a final sample size of 247 participants.

Conclusions

This study provides insights into the role of sensory hypersensitivity in the relationship between social anxiety and separation anxiety with insistence on sameness (IS). Our findings suggest that sensory hypersensitivity may be an important factor to consider in understanding these behaviors, particularly in individuals with lower levels of autistic traits. Future therapeutic interventions for children with ASD may benefit from considering the impact of separation anxiety and social anxiety on these children. Addressing the role of sensory sensitivity and applying behavioral interventions to alleviate these symptoms may enhance the outcomes.