Introduction
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by persistent deficits in social reciprocity and communication, stereotyped behaviors, and restricted interests [1]. Approximately ASD affects 1 in 100 children worldwide [2]. Treatment methods such as occupational therapy and speech therapy [3، 4] or a combination have significantly improved these children who have problems understanding their environment due to their inability to process information received through their senses [5-7]. In other words, any sensory stimuli can interfere with the sensory processing of these children.
One of the best and most reliable methods of evaluating autistic children is examining their sensory processing [8]. Sensory processing is directly related to sensory threshold. Maintaining a balance between low and high thresholds allows people to pay sufficient attention to the elements around them without overloading with information and losing focus and control over their attention. Maintaining this balance is considered part of learning in the central nervous system. Data from studies of sensory processing using the sensory profile have revealed evidence of new relationships, especially the interaction of neuroscience and social science [9]. Dunn’s sensory processing model results from these studies [10], which clearly defines and evaluates the quality of sensory processing.
The ASD children spend a lot of time in therapeutic environments, so we cannot overlook the role of architecture in designs compatible with the special sensory conditions of these children. Obviously, the children’s homes, schools, social environments, and therapeutic centers can be very different; however, it is ideal to try to provide suitable environments for children to interact with the environment [11]. Recently, the research conducted about the link between architecture and autism or the design of autism-friendly environments shows that appropriate architecture can improve the states of children in terms of behavior, communication, play, learning, and even the quality of sleep of children with ASD [12-14]. 
An essential part of treating children with autism disorder is to meet their sensory needs, which is possible through intervention and adaptation to the environment (sensory regimen). The clinic environment must correspond to the real needs of these children. Sensory factors (auditory/visual/touch) and movement (behavioral/emotional-social/mental responses) are among the most critical factors that can affect the treatment process of these children [15]. For this reason, a comparison was made between treatment outcomes in two different environments to observe the architectural factors that improve the quality of medical services.

Materials and Methods
Fifty children with autism were included in the study using an available sampling. The inclusion criteria were as follows: Being 3 to 14 years old, being diagnosed with ASD by a specialist, and gaining consent from the parents of the autistic child and the occupational therapy center to participate in the study. The exclusion criteria were as follows: The autistic child suffering from other neurological disorders, the child who has psychological disorders, and the unwillingness of parents or occupational therapy centers to continue cooperation. After examining the inclusion and exclusion criteria, a written consent form was obtained from all parents of children with autism and the officials of occupational therapy centers who met the inclusion criteria for the study.
A questionnaire designed in a previous study was used to rank the physical space of rehabilitation centers related to autistic children [16]. This questionnaire included 30 factors such as intensity of natural light, quality of light (natural or artificial), visibility and view from inside the building to outside, noise and visual pollution, and the color of the walls. This questionnaire included the main criteria affecting rehabilitation outcomes based on a survey of 32 occupational therapists and parents of 50 children (Table 1).



In the above questionnaire, its face and content validity were evaluated qualitatively, and the alpha coefficient for the total score of this questionnaire was reported as 0.81. Based on the items that got the highest score in the evaluation from parents and therapists (Table 2), therapeutic environments were divided into two groups of standard and non-standard environments, and the present study was designed and conducted. 
The short sensory profile was used to measure the sensory processing abilities (sensory seeking, sensory avoidance, sensory sensitivity, and sensory registration) of children with autism disorder. This questionnaire designed by Dunn (2014) has 34 items and is most effective for the age range of 3 to 14 [10]. The scoring of the questionnaire is on a 6-point Likert scale (almost always, often, sometimes, rarely, almost never, and never). The factors examined in this questionnaire include sensory processing (14 questions) and behavioral responses related to sensory processing (20 questions).




Data analysis
The normality of the data distribution was checked by the Shapiro-Wilk test before data analysis. Considering the normality of the data distribution, an independent t-test was used to compare sensory seeking, avoidance, sensitivity, and registration of children with autism disorder in two standard and non-standard educational environments, and a paired t-test was used to examine the effect of therapeutic interventions in each group. The difference in means was considered significant at the 0.05 level. All analyses were performed using SPSS software, version 21.

Results 
In this study, 50 children (39 boys and 11 girls) with ASD with a mean age of 8.26±2.2 years participated in the study. They were treated in occupational therapy centers in Tehran City, Iran, in 2022-2021 after receiving written consent from their parents. Based on the evaluation of the physical space of the rehabilitation centers by the architectural criteria of the treatment environments presented in Table 2, the treatment centers of these children were divided into standard and non-standard centers. Among them, 12 unsuitable and 8 suitable centers were evaluated and, after the clinic officials’ consent, were included in the study for evaluation.
According to the results (Table 3), standard and non-standard treatment environments effectively improved all 4-factor models of sensory processing, including sensory seeking, avoidance, sensitivity, and registration (P=0.04). According to the significant difference (P˂0.01) of the changes in these sensory processing patterns between the two groups after completing the treatment course in standard and non-standard environments, the design of standard specialized spaces for autism treatment, the elements affecting the quality of architecture and physical elements such as the color of the environment, the intensity and quality of natural light, the noise pollution of these spaces, and other factors mentioned in Table 2 had a significant impact on the results of the treatment of these children in terms of sensory processing. In other words, children treated in favorable environments in terms of architectural features showed a better and more favorable development of sensory processing compared to centers that lacked favorable environmental conditions.




Discussion 
Since one of the effective and positive factors in the impact of rehabilitation services on children with ASD is the physical environment that governs the rehabilitation places of these children, appropriate treatment spaces can be very effective in the process of their health and learning [17]. Considering the factors affecting the quality of rehabilitation in the treatment-educational centers of autistic children, its effect on the rehabilitation intervention process of these patients was investigated in the present study. A previous study showed that children with autism are more sensitive to light than any other element in the interior design of the environment, so light is used to develop their skills in the multisensory room [14]. However, in that study, only the light factor was considered. In other studies, many aspects of the physical environment and their possible impact on the treatment results of these children have not been addressed [18-20]. This study aimed to investigate the effect of physical factors and the design of spaces in rehabilitation environments on the results of occupational therapy for children with autism. The results of the present study showed the improvement of children’s sensory processing in both therapeutic environments after a period of occupational therapy, although in comparison between the two groups, the results of the assessment of children’s sensory processing in the group of standard environments in terms of architectural features are notably better, showing a more favorable attitude.
It is known that different people’s sensory processing ability is different. Considering the importance of sensory processing in learning and the ability to adapt to regulate sensory processing, a suitable sensory regimen is essential for people [21]. This sensory regimen can include stimuli from the physical environment, manners, clothing, and all things related to daily activities [22]. In the context of the physical environment, suitable architectural features can change people’s degree of adaptation, and a suitable and standard environment in terms of architectural factors can provide suitable adaptation for people.
Factors such as the need for support, not hearing and ignoring speech, the need for more care in life, inability to perform activities and getting nervous, too much noise in the environment, anxiety in the visual changes of the activity environment, less participation in the group, getting tired, getting frustrated easily, desire for flavors, lack of cooperation, not making eye contact are considered the most important factors of sensory processing from the point of view of parents of children with autism. Previous studies have shown that factors such as the presence of a dark room are very effective in improving the sensory processing pattern of children with ASD. This issue is among the factors that have been suggested to be considered in the architectural design of therapeutic spaces to improve the educational process of these patients [23]. From the perspective of measuring the quality of architecture, factors such as the quality of ventilation, noise pollution in the educational environment, the quality of natural and artificial light in the educational environment, the usefulness of the dimensions of the partitions, and the existence of a dark room, have the greatest impact on the quality of rehabilitation of children with autism. Based on this, it is suggested that in the case of standardization of the architectural space design of rehabilitation centers, the sensory processing factors in these children will be significantly improved.
Based on the present study findings, the architecture of therapeutic environments showed a statistically significant effect on the rehabilitation of children with ASD. In the current study, the difference between the 4-factor patterns of sensory processing in two groups of proportional and non-proportional therapeutic environments, which were differentiated based on the proposed effective architectural criteria, showed a significant difference. Accordingly, interior architectural designs are effective in renovating the space for more and more favorable effects of the children’s rehabilitation program. In other words, it is necessary to consider factors such as the acoustic condition of the space, light condition, height proportions, texture and materials, color, proper heating and ventilation, space organization, and predictability of spaces in designing and creating a therapeutic space for children with ASD. By complying with these conditions in the design of the treatment environment for these children, it is expected that sensory processing is done perfectly. Consequently, the rehabilitation treatment of children suffering from this disorder will have a better quality.
According to the present study results, it is suggested that architects and building designers in the designs of rehabilitation centers, especially rehabilitation centers for children with ASD, should take the necessary measures to reduce noise pollution by designing sound insulation systems for the walls, windows, and also to control visual pollution, pay attention to the color scheme of the therapeutic environment, the quality and intensity of natural and artificial light in the environment. Carefully designing the windows’ dimensions, using thick curtains, transparent glass, wide and regular ceiling lighting, and linear or hidden single lights can be very effective.

Conclusion
The results of this research showed that the physical factors of rehabilitation environments have a significant effect on the sensory processing patterns of children with autism disorder, which can be effective in improving the quality of rehabilitation services. Therefore, the architectural features of therapeutic environments that pay particular attention to the control of noise and visual pollution can be used to standardize rehabilitation spaces and develop a national architectural standard.
The present study was conducted only in occupational therapy centers in Tehran, considering the variety of architectural features related to the culture of each province and city, as well as the diversity of the facilities of occupational therapy centers. It is suggested that a wider study be conducted at the national level. Another limitation of this study was to examine the effect of the architecture of the occupational therapy center environment on the results obtained in autistic children, and its results cannot be generalized to other therapeutic interventions and other disorders with sensory processing problems, such as children with attention deficit hyperactivity disorder. Considering that the subject investigated in this research is one of the new topics in the field of children with sensory processing problems, additional studies should be conducted on children with other sensory processing disorders.

Ethical Considerations

Compliance with ethical guidelines
This study was approved by the Research Vice-Chancellor of the Faculty of Technology and Engineering, Saveh Branch, Islamic Azad University (Code 18160202952016). The participants were fully informed about the research objectives. In addition to obtaining written consent, they were assured that the information obtained from them would remain confidential, and they were also allowed to withdraw from the study at any time.

Funding
The paper was extracted from the PhD dissertation of Negin Irani, approved by Department of Architecture, Faculty of Engineering, Saveh Branch, Islamic Azad University. 

Authors' contributions
Conceptualization: Nagin Irani and Navid Mirzakhani; Methodology and analysis: Cyrus Bavar and Sasan Khademi Kalantari; Research: Nagin Irani and Sasan Khademi Kalantari; Editing and finalization: Alia Daryabar; Supervision: Marzieh Pashmdarfar. 

Conflict of interest
All authors declared no conflict of interest. 

Acknowledgments
The authors express their gratitude to the faculty members of the Department of Physiotherapy and Occupational Therapy, Faculty of Rehabilitation, Shahid Beheshti University of Medical Sciences and Islamic Azad University, Saveh Branch, and the all of participants of the study.

 

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