1. Introduction
Intellectual disabilities, commonly referred to as intellectual impairments, are categorized into four levels of severity: mild, moderate, severe, and profound, based on the degree of cognitive impairment [
1]. Additionally, depending on the accompanying physical and neurological impairments, these disabilities can be further classified into specific types, including Pure Intellectual Disability(Pure-ID), Down Syndrome (DS), Cerebral Palsy (CP), and Autism Spectrum Disorders (ASD) [
2]. Global data indicates that ID are neurodevelopmental disorders that affect approximately 3% of children and adolescents [
3]. Individuals with ID often face a range of behavioral challenges, such as varying levels of hyperactivity, maladaptive emotions, inappropriate social interactions, and aggressive tendencies, which hinder their ability to engage in prosocial behavior [
4]. In comparison to typically developing children, those with ID generally exhibit higher levels of problem behavior [
5], coupled with lower levels of physical fitness encompassing speed, agility, strength, flexibility, balance, coordination, reaction time, cardiovascular endurance, and muscle endurance [
6]. Problematic behaviors associated with ID significantly contribute to the manifestation of antisocial behavior and social rejection during adolescence and adulthood [
7].
Gross motor displacement skills refer to the body's ability to move and change position in space [
8]. These skills are crucial indicators for assessing gross motor movements, which, in turn, have a positive impact on physical health and cognitive development [
9,
10]. The development of fundamental motor skills during childhood significantly influences cognitive functions and the maturation of the motor nervous system [
11]. However, children with ID experience delayed development of basic motor skills compared to their typically developing peers [
12]. Research indicates that the degree of ID affects motor performance [
13], with children with mild ID displaying better motor skills than those with severe ID [
14]. Additionally, there is a correlation between intellectual level and motor coordination ability, as children with marginal, mild, and moderate ID score lower on displacement skills compared to typically developing children [
15,
16]. A study discovered a correlation between the severity of intellectual disability in children and their level of physical activity [
17], as well as the severity of their learning disabilities [
18]. However, there is limited research available regarding the variations in displacement skill levels among different degrees of disability. Scholars have conducted research on the developmental characteristics of gross motor movements in children with ASD [
19] and DS [
20], shedding light on the development of basic Displacement skills in children with various ID. However, there have been no reports comparing the levels of displacement skills among children with specific ID, DS, and ASD. It is essential to recognize the significance of developing displacement skills in children with ID as it positively contributes to their cognitive functions, physical health, motor coordination, and overall physical activity levels.
During the mid-1990s, the American Psychiatric Association defined problem behavior as behaviors exhibited by individuals that deviate from prevailing social norms and age-appropriate expectations, persisting over an extended duration and influencing the individual's own life or the lives of others to varying degrees [
21]. Research consistently demonstrates that children with ID exhibit higher levels of problem behavior compared to typically developing children [
22]. Common behaviors include excessive emotional reactivity [
23], while psychiatric disorders, oppositional behavior, and antisocial behavior tend to be more pronounced [
24]. Children with ID often experience specific cognitive deficits [
25], accompanied by sensory integration dysfunction, which is more prevalent in this population than in typically developing children [
26]. Moreover, sensory integration is intricately linked to both physical fitness and problem behavior [
27]. Studies also indicate a strong correlation between lower physical fitness levels and increased rates of problem behavior in children [
28]. Additionally, there is a close relationship between basic motor skills, health status, and problem behavior in this population [
29]. However, existing literature does not report a direct link between displacement skills and problem behavior in children with ID. Further investigation is necessary to determine potential variations in displacement skills and problem behavior characteristics among different types of ID (e.g., specific ID, DS, ASD, etc.). Moreover, it is crucial to assess whether displacement skills in children with varying degrees and types of ID have predictive value for problem behavior.
Consequently, this study aims to investigate the characteristics and associations between displacement skills and levels of problem behavior in children with diverse degrees and types of ID.
2. Methods
2.1. Participants
Through the selection of 90 children with intellectual disabilities who successfully completed the assessments, participants were chosen from two specialized educational institutions, consisting of 70 males and 20 females (
Figure 1). These participants had an average age of (9.13±1.73) years, an average height of (135.30±12.37) cm, and an average weight of (34.18±11.90) kg. Their classification was based on their intelligence quotient (IQ) and social adaptability, resulting in four disability levels: mild (50~69), moderate (IQ=35~49), severe (IQ=20~34), and profound (IQ<20). Their IQ was evaluated using the Wechsler Intelligence Scale [
1]. Additionally, considering the accompanying physical and neurological impairments associated with intellectual disabilities, they can also be classified into various types, including Pure-ID, DS, and ASD [
2]. By reviewing the academic records of these 90 participants, the severity of intellectual disability was categorized into three levels: moderate (
n=36), severe (
n=35), and profound (
n=19). The types of intellectual disabilities included Pure-ID (
n=21), DS (
n=12), and ASD (
n=57), totaling three distinct categories.
2.2. Materials
2.2.1. Body morphology
The height and weight of the participants were measured using the In Body J30 pediatric body composition analyzer, manufactured by Bio space, a Korean company. Participants were instructed to stand barefoot on the device with relaxed bodies, hold the sensors with both hands, and gaze straight ahead while removing their shoes and socks during the test.
2.2.2. Displacement Skills
Test of Gross Motor Development-Ⅱ (TGMD-2) was used to evaluate the displacement ability of children with ID [
8]. The test assesses six movements, including running (8 points), sliding forward (8 points), jumping sideways (6 points), one-legged jump (10 points), standing long jump (8 points), and side sliding (8 points). Each movement is scored as either 1 point for "compliance" or 0 points for "non-compliance". The test is conducted twice, and the maximum score is 48 points. The TGMD-2 has been cross-culturally validated and demonstrated good reliability and validity [
33]. This study found that the gross motor displacement skills had a Cronbach's α coefficient of 0.859, indicating good internal consistency.
2.2.3. Problematic Behaviors
The Strengths and Difficulties Questionnaire (SDQ) is a reliable tool developed by Goodman R to assess the psychological well-being of special children and adolescents. It consists of 25 items across five dimensions [
30]. The difficulty score is evaluated through 20 items and includes four dimensions: emotional, conduct, hyperactivity, and peer problems, which assess negative emotions and problematic behaviors of the subjects. The strengths section includes five items that evaluate positive behaviors of the subjects in the prosocial behavior dimension [
31]. The SDQ questionnaire is a valid tool for assessing problem behaviors in children with ID in clinical diagnosis [
32].
2.3. Procedure
The data for this study was obtained from a research project conducted by the National Research Center for Early Childhood Physical Education Development at Chengdu University. Approval for the project was granted by the Ethics Committee of Sichuan Normal University, and the study was carried out from March to May 2022, encompassing all the tests.
The testing involved the distribution of questionnaires and on-site assessments. The study examined the growth records of 90 participants within the past three years, excluding those without growth records from the screening process. The test subjects were children with intellectual disabilities, and their participation required parental consent, with parents present throughout the entire process. To ensure participant privacy, each individual was assigned a unique code instead of using their names for testing and evaluation purposes.
The study included students with ID from special schools who had lower cognitive comprehension abilities. Prior to testing, teachers, parents, and examinees received 3-5 instructions and demonstrations. For severely disabled children who could not comprehend during testing, teachers and parents guided and motivated them to complete the demonstration again. The test was scored by a primary examiner and an assistant who had not engaged in any physical activity before the test and met the physical requirements. The scoring criteria were standardized, and the entire test process was videotaped. The test exercises were conducted in the following order: running, forward sliding step, stepping jump, single-leg jump, standing long jump, and lateral sliding step.
The SDQ parent version is a questionnaire that the homeroom teacher of the corresponding class distributes to evaluate children. The teacher provides training to the main investigator and explains the requirements for filling out the questionnaire. Parents fill out the questionnaire on site, and it is immediately collected upon completion. The investigators then conduct a unified count and sorting of the questionnaires. If parents encounter difficulties while completing the questionnaire, the investigators provide one-on-one assistance. To ensure the questionnaire's authenticity and validity, the investigators conduct follow-up phone calls or require parents to fill out the questionnaire again if there are issues such as missing or multiple answers.
2.4. Data Analysis
The data were analyzed using
SPSS 22.0 and expressed as mean ± standard deviation(
M±
SD). Multivariate covariance analysis was used to examine the differences in displacement skill and problem behavior in relation to the degree and type of ID in the subjects. The effect of variance analysis was evaluated using the local Eta square test (
η2), with the correlation coefficient standards for small, medium, and large effect sizes being 0.01, 0.06, and 0.14 [
34]. Partial correlation analysis was used to test the correlation between displacement skill and problem behavior, with the correlation coefficient standards for weak, moderate, and high effect sizes being 0.1, 0.3, and 0.5 [
13]. Multivariate linear regression analysis was conducted to investigate the impact of displacement skills on problem behavior in children with varying degrees of ID. Subject gender, age, and body weight were used as controls, ID degree was the independent variable, problem behavior was the dependent variable, and the degree of influence was evaluated using the standardized coefficient
β. The model interpretation rate was measured using the change in
R2. The significance level for the differences in the data analysis results was set as follows:
P<0.01 for extremely significant, 0.01<
P<0.05 for significant, and 0.05<
P<0.1 for marginally significant.
5. Conclusion
1) After children with different levels of ID are analyzed, it is found that those with moderate ID display higher levels of displacement skills and strength scores, but lower difficulty scores, compared to those with severe and profound ID.
2) Among children with varying degrees of ID, those with ASD exhibit higher levels of adaptive skills compared to those with Pure-ID and the DS. Children with Pure-ID exhibit the most significant behavioral symptoms.
3) A correlation exists between adaptive skills and challenging behavior in children with ID. Adaptive skill scores have a predictive role in challenging behavior, especially in children with moderate ID. The adaptive skills of children with moderate ID significantly affect their overall score and difficulty score on the SDQ. Likewise, the adaptive skills of children with severe ID significantly affect their overall score on the SDQ,suggesting that the development of displacement skills in children with ID can have a positive impact on their accompanying problem behavior.