Abstract
Importance
Sensory integration (SI) typically follows a normal sequence of development. Its evaluation is crucial for evidence-based interventions.
Objective
To examine the relationship between age and performance on the Evaluation in Ayres Sensory Integration (EASI) vestibular and proprioceptive tests and to compare linear and nonlinear models.
Design
Normative data from the EASI tests were collected and used for model-building to characterize age effects on SI abilities.
Setting
Laboratory in Taiwan.
Participants
Children (N = 209) ages 3–12 yr.
Outcomes and Measures
Occupational therapists (N = 23) from various regions of Taiwan collected data from typically developing children. Linear and nonlinear (quadratic and hyperbolic) models were used to examine the relationship between age and test performance.
Results
Linear models accounted for 36%-43% of the variance in vestibular and proprioceptive test performance. Nonlinear models performed slightly better, explaining 42%–48% of the variance. The sum of squared errors was lower for nonlinear models (2,943–3,832) than for linear models (3,944–4,223). The hyperbolic model generally showed the highest R2 (explained variance) and the lowest root-mean-square error of approximation, except for the Joint Position test, where it did not outperform the other models.
Conclusions and Relevance
We developed a clinically applicable system for assessing vestibular and proprioceptive functions. The results showed marked developmental improvements, especially between ages 7 and 9 yr. The findings suggest that occupational therapists can use a hyperbolic model with EASI vestibular and proprioceptive tests to better identify SI challenges, which supports the development of evidence-based intervention plans.
Plain-Language Summary
Sensory integration plays a vital role in children’s typical development and tends to follow a predictable pattern as they grow. The Evaluation in Ayres Sensory Integration (EASI) is a tool that is used to assess children’s sensory, motor, and motor planning skills. This study focused specifically on the vestibular and proprioceptive tests. The vestibular system in the inner ear maintains balance, posture, head position, and keeps our eyes stable during movement. Proprioception lets us sense limb position without seeing them. We assessed 209 children between the ages 3 and 12 years to explore how performance on these tests changes with age. We compared two types of models: (1) a linear model (which assumes steady, constant growth) and (2) a nonlinear model (which allows for more complex growth patterns). The results showed that the nonlinear hyperbolic model better captured how children’s vestibular and proprioceptive abilities develop over time. One key finding was that these skills improved most noticeably between the ages of 7 and 9 years. We developed a clinical decision support system using the EASI vestibular and proprioceptive tests. For occupational therapists, this means that applying a hyperbolic model to interpret test results may lead to more accurate identification of sensory integration difficulties. This enhanced approach can guide the development of evidence-based intervention plans.
The authors developed a clinically applicable system for assessing vestibular and proprioceptive functions to examine the relationship between age and performance on the Evaluation in Ayres Sensory Integration.
Sensory integration (SI) is an important area of intervention in pediatric occupational therapy (Schaaf et al., 2018). Studies that have examined theory use among pediatric occupational therapists have found that the developmental and SI models are the most commonly applied ones in work with infants and young children (Brown et al., 2005; Lawlor & Henderson, 1989). As early as 1999, Case-Smith and Bryan reported that occupational therapists in the United States who work with children with autism in school settings most frequently used a sensory-integrative approach. Nearly 90% of American occupational therapists practicing in school settings use principles of SI theory—originally developed by Ayres (1972, 1978)—to support children with learning disabilities, attention deficit hyperactivity disorder, autism, or behavioral challenges related to difficulties in processing and organizing sensory input (Schaaf et al., 2018; Schoen et al., 2019; Storch & Eskow, 1996).
Effective evaluation of SI is crucial for providing interventions that are based on evidence. To achieve this, standardized assessment tools are necessary because they offer objective and reliable results for evaluating SI function (Schoen et al., 2014). A comprehensive and systematic evaluation is the basis for formulating intervention plans that are both clinically and cost-effective (Schaaf, 2015; Schaaf & Mailloux, 2015). Schaaf et al. (2014) emphasized that to develop effective SI interventions, clinicians must first use appropriate assessment tools that accurately identify and describe the sensory and motor characteristics of children with SI challenges.
The Evaluation in Ayres Sensory Integration (EASI) has been developed as a valid evaluation tool for use in clinical practice (Mailloux et al., 2018). It is designed to evaluate the child’s abilities in sensory perception; ocular, postural, and bilateral motor integration; and praxis and sensory reactivity functions, and it includes four major categories that comprise a total of 20 tests. As part of a larger, global effort by the Ayres Sensory Integration® (ASI) project (https://www.cl-asi.org/) to collect standardized norms specific to different geographic regions and ethnicities, the Taiwan EASI team initiated this study to investigate the developmental patterns shown by the EASI tests.
SI typically follows a normal developmental sequence; however, only a few studies have examined how age influences SI function in children during their development. Some studies have used statistical methods, such as analysis of variance (ANOVA) or linear regression, and found age to be an important factor, and one study noted a weak positive correlation between age and EASI praxis scores. Lin et al. (2013) found statistically significant age-related differences across four age groups (3–4, 5–6, 7–8, and 9–10 yr), highlighting age as a key factor in seven SI tasks. According to the manual for the Sensory Integration and Praxis Tests, vestibular and proprioceptive-related abilities tend to increase with age (Ayres, 1989). In research that evaluated the validity of the Sensory Processing 3-Dimesions Scale, Mulligan et al. (2019) also examined age-related trends and found that proprioceptive and vestibular sensory system functions improved with age, as expected. Similarly, Lamash et al. (2022) reported a weak but statistically significant positive correlation between age and EASI praxis test scores, indicating a developmental trend.
The vestibular and proprioceptive systems are considered foundational in ASI theory. Smith et al. (2005) found that deficits in vestibular function not only impair balance and posture but also negatively affect attention and increase attention demands. Troubles with vestibular functioning have been linked to deficits in object recognition, spatial navigation, learning, and memory, and these SI difficulties affect children’s daily performance and participation. Previous research has shown that vestibular–proprioceptive challenges are common among children with cochlear implants (Koester et al., 2014), autism (Roley et al., 2015; Siaperas et al., 2012), and those with other learning and developmental concerns (Mailloux et al., 2011).
The EASI vestibular and proprioceptive tests have demonstrated robust construct validity and internal reliability, making them sound tools for measuring these often-hidden difficulties (Mailloux et al., 2021). Nevertheless, until now, no studies have specifically investigated the age trends for these vestibular– proprioceptive functions as measured by the EASI vestibular and proprioceptive tests.
Understanding the development of SI across childhood is crucial for educators, psychologists, and health care professionals. Age-referenced norms serve as benchmarks that allow professionals to assess whether a child’s development aligns with what is typical for their age. Characterizing this development across chronological age is essential for practical clinical application. Although linear models have traditionally been used to describe developmental progress, many behavioral, health, and educational outcomes are thought to follow nonlinear trajectories (Sterba, 2014). This suggests that constructing and applying nonlinear models to capture these inherent developmental patterns is both practical and essential (Roberts, 1986; Sterba, 2014).
Nonlinear hyperbolic models are considered particularly valuable in clinical applications. These models, which can describe sigmoid-like curves often seen in empirical data, allow for the estimation of key characteristics of the developmental process. These characteristics include initial ability levels, rates of change during developmental spurts, and maximal or asymptotic levels (Grimm et al., 2011; Ram & Grimm, 2007). Hanna et al. (2009) estimated nonlinear models of motor development on the basis of the assumption that children’s motor scores rise toward a limit of motor ability. A benefit of nonlinear latent curve models is that their functional forms are numerous, and therefore many different patterns of change can be modeled (Ram & Grimm, 2007).
Given this context and the identified gap in research, the primary aim of this study was to characterize how age affects scores on the EASI vestibular and proprioceptive tests. We further used regression models to analyze the relationship between age and vestibular and proprioceptive test scores as part of the validity analyses supporting the development of a future norm-referenced model. We explored both linear and nonlinear (quadratic and hyperbolic) regression models and compared them to determine the best fit for the developmental data.
To achieve these aims, we sought to answer the following three research questions by studying a sample of typically developing children ages 3– 12 yr:
Do the EASI vestibular and proprioceptive tests administered in Taiwan show reliable internal consistency? Are each of the six EASI tests valid in measuring age-related changes in the relevant abilities? Is the nonlinear hyperbolic function a better fit for the regression model than the linear one?
Method
Approval for this study, which included data collection on all 20 EASI tests, was obtained through the E-Da Hospital Institutional Review Board (IRB; No. EMRP46111N).
Participants
This study involved the collection of normative data from the EASI tests as part of a larger project by the Taiwan EASI team. Information on the SI development of typically developing children was collected according to population distribution ratios in Taiwan. All testers were occupational therapists or occupational therapy students. We recruited 15 testers through an announcement to the Occupational Therapists Union of Taiwan and eight testers from our institute (five were research assistants, and three were students). Testers completed online training modules, submitted sample test scores to check adherence to the scoring format, recruited participants, and obtained parental consent and child assent per IRB requirements.
In general, testers recruited children from local schools. For the purposes of reliability, validity, and norm-related data collection, a total of 213 children (113 girls and 100 boys) with typical development between ages 3 and 12 yr were initially collected. The age distributions of the participants were as follows: 3– 5 yr (n = 71), 6–8 yr (n = 101), and 9–12 yr (n = 41). The statistical analysis and model construction were performed on a study population that comprised 209 children ages 3–12 yr.
Exclusion Criteria
Children were excluded from the study if they met any of the following criteria: ▪ known medical, educational, mental health, or other developmental problems; ▪ had been judged by relevant professionals to have SI problems; ▪ had received treatment services for conditions such as a learning disability, autism, hyperactive attention deficit disorder, language delay, self-regulation problems, hypotonia, and developmental coordination disorder; or ▪ had clear impairments, including neurological disorders (brain injury, cerebral palsy, myelocele), cognitive impairment, or visual or hearing impairment.
Measures (Tests of Vestibular and Proprioception-Related Functions)
The final versions of the EASI tests are still being finalized by the ASI team; however, in this study we used the most current versions. The children were scored on only six specific tests from the EASI that measure distinct aspects of vestibular and proprioceptive functions. Posture Control (PC): EASI Test 5. The 19-item PC test measures the child’s postural control by examining their ability to adjust posturally through corrective reflexes and balance responses in various positions and movements. Each PC item is scored 2, 1, or 0 for Prone Extension (7 items), Supine Flexion (6 items), Head Lag (1 item), Postural Control on Ball (1 item), Robot Arms (1 item), and Reaching (3 items). The total score ranges from 0 to 38. Balance (Bal): EASI Test 6. The purpose of the 12-item Bal test is to assess a child’s balance ability, including static and dynamic balance with eyes open and closed. The time for maintaining in stable posture is scored 1 or 0 for Items 1–2 and scored 2, 1, or 0 for Items 3–12. The total score ranges from 0 to 22. Proprioception: Force (Prop: F): EASI Test 7. The 10-item Prop: F test is designed to assess a child’s ability to grade the use of force when they draw a circle with a crayon and roll a bottle. Each Prop: F item is scored 2, 1, or 0 for Crayon (6 items) and Rolling (4 items). The total score ranges from 0 to 20. Ocular Motor and Praxis (O: M&Pr): EASI Test 8. The purpose of this 22-item test is to assess a child’s ability to perform ocular motor skills (OcM) and to imitate eye movements (Pr:Oc). Each OcM item is scored 2, 1, or 0 for Pursuits (6 items), Stabilization (4 items), and Quick Localization (4 items). Each Pr:Oc item is scored 2, 1, or 0 for Praxis (8 items). The total score ranges from 0 to 44. Bilateral Integration (BI): EASI Test 10. This 15-item BI test is designed to assess children’s motor coordination, smoothness, and rhythm and includes 15 items on both sides of the body, upper and lower limbs. Some of the tests were based on what Ayres (1972) initially called “clinical observations,” such as the finger-to-nose test, diadokokinesis, and finger touching. Each BI item is scored 2, 1, or 0 for Arms/Sitting (9 items) and Body/Standing (6 items). The total score ranges from 0 to 30. Proprioception: Joint Position (Prop: JP): EASI Test 14. This 10-item Prop: JP test is designed to assess a child’s ability to imitate joint positions. It focuses on the sense of joint positions of the preferred hand and the lower limb. Each Prop: JP item is scored 2, 1, or 0 for One Hand (6 items) and for One Foot (4 items). The total score ranges from 0 to 20.
Data and Statistical Analyses
Raw scores were used for all data and statistical analyses. To explore a new modeling system, we analyzed raw scores using ANOVA and regression in relation to participants’ chronological ages. Data analyses were conducted using SPSS (Version 25). Descriptive statistics, including frequencies, means, and standard deviations, were computed for demographic variables and scores on the six EASI tests. To assess reliability, Cronbach’s α was used to address internal consistency. We evaluated split–half reliability using the Spearman–Brown formula. We analyzed differences in test scores across age groups and between genders using a two-way ANOVA, followed by post hoc comparisons with Bonferroni correction. The purpose of the two-way ANOVA was to determine whether boys and girls should be scored separately in the information system.
We conducted a regression analysis to explore the relationships between test scores and participants’ age. Both linear regression and nonlinear curve fitting techniques were applied to investigate the nature and shape of this relationship. We estimated the parameters for the models using least-squares minimization techniques.
We explored and compared the fit of three regression models: (1) a linear model, the most widely used fitting curve, which assumes a straight-line relationship between age and scores; (2) a nonlinear quadratic model, most often used when a linear change model does not fit well, which accommodates specific kinds of nonlinearity in the changing pattern; and (3) a nonlinear hyperbolic model, specifically, the hyperbolic tangent equation, which generally is used for describing empirical data with a sigmoid-like curve. This last model was considered valuable for defining characteristics of the developmental process, such as initial levels, rates of change during developmental spurts, and maximal asymptotic levels.
Results
The internal consistency and split–half reliability metrics for the six EASI tests are presented in Table 1. Internal consistency, measured with Cronbach’s α, ranged from .667, for Prop: F, to .903, for BI, indicating medium to high internal consistency. Split–half reliability, evaluated with the Spearman–Brown formula, ranged from .664, for Prop: JP, to .874, for Bal, also demonstrating medium to high reliability.
EASI Vestibular and Proprioception Function Tests: Internal Consistency and Split–Half Reliability
Note. Bal = Balance; BI = Bilateral Integration; EASI = Evaluation in Ayres Sensory Integration; O: M&Pr = Ocular Motor and Praxis; PC = Posture Control; Prop: Force = Proprioception: Force; Prop: JP = Proprioception: Joint Position.
The descriptive statistics and the results of the two-way ANOVA are presented in Tables 2 and 3, respectively. The analysis revealed significant main effects of age in all six tests, but not of gender. Statistically significant differences were observed across age groups (3–5, 6–8, and 9–12 yr) on all six tests, with post hoc Bonferroni corrections indicating that scores for the 9–12 age group were considerably higher than those for the 6–8 group, which were notably higher than those for the 3–5 age group. Note that a statistically significant interaction effect was identified in the Bal test, on which boys exhibited notable differences across age groups, whereas girls showed sizable differences only between the ages of 3–5 and 6–8, but not between ages 6–8 and 9–12.
EASI Vestibular and Proprioception Function Tests: Score Means and Standard Deviations
Note. Bal = Balance; BI = Bilateral Integration; EASI = Evaluation in Ayres Sensory Integration; OM&Pr = Ocular Motor and Praxis; PC = Posture Control; Prop: Force = Proprioception: Force; Prop: JP = Proprioception: Joint Position.
Results of a Two-Way ANOVA Among Group A (3–5 Yr), Group B (6–8 Yr), and Group C (9–12 Yr)
Note. ANOVA = analysis of variance; Bal = Balance; BI = Bilateral Integration; O: M&Pr = Ocular Motor and Praxis; PC = Posture Control; Prop: Force = Proprioception: Force; Prop: JP = Proprioception: Joint Position.
*p < .05. ***p < .001.
The outcomes of regression analyses conducted on the six vestibular and proprioceptive tests, which compared the fit of linear, quadratic, and hyperbolic models using R 2 and root-mean-square errors (RMSEs), are presented in Table 4. The linear model consistently exhibited the lowest coefficient of determination (R 2) and the highest RMSE. The nonlinear hyperbolic model demonstrated the highest R 2 and the lowest RMSE for most tests. An exception was observed in the Prop: JP test, where the RMSE of the hyperbolic model (7.635) surpassed that of the quadratic model (7.607). In the linear model, the proportion of explained variance (R 2) across the six vestibular and proprioceptive tests ranged from 31.3% to 52.0%.
Fit Statistics
Note. Bal = Balance; BI = Bilateral Integration; EASI = Evaluation in Ayres Sensory Integration; O: M&Pr = Ocular Motor and Praxis; PC = Posture Control; Prop: Force = Proprioception: Force; Prop: JP = Proprioception: Joint Position; RMSE = root-mean-square error of approximation.
Figures 1 and 2 show the scatter plots and curve fittings of the linear, quadratic, and hyperbolic models. For purposes of clarity, and to reduce overlapping, the fitting curves of hyperbolic model were plotted and are shown in Figure 2. Figure 2 also marks the age at which individuals attain 90% of the maximal score on the EASI vestibular and proprioceptive tests. Among the six vestibular and proprioceptive tests, the PC test showed the fastest rate to reach 90% of the score, at approximately age 12 yr, predicted at 6.8128 yr. In contrast, the Prop: JP test showed the slowest rate to reach 90%, predicted at approximately 10.1053 yr.
Scatter plots and linear and quadratic fitting.
Scatter plots and hyperbolic fitting.
Discussion
The results of the two-way ANOVA confirmed that age is indeed a significant factor in determining vestibular and proprioceptive ability. This finding prompted further analysis in which we used both linear and nonlinear regression models with age as a key variable. Gender showed no statistically significant differences in developmental trends between boys and girls, suggesting that they can generally be combined for analysis. However, a significant interaction between age and gender was found for the Bal test, indicating that a gender-specific approach may be necessary for that test.
The findings of this study offer insights into the reliability of the EASI vestibular and proprioceptive tests and characterize the age-related development of vestibular and proprioceptive functions in typically developing children when linear and nonlinear approaches are used. With respect to reliability, the EASI vestibular and proprioceptive tests demonstrated moderate to high internal consistency in this sample of children and young adolescents ages 6–12 yr; specifically, the PC, Bal, O: M&Pr, and BI tests exhibited strong internal consistency. However, the Prop: JP and Prop: F tests showed less robust internal consistency. This finding is consistent with previous research by Mailloux et al. (2021), who also reported the lowest Cronbach’s α values on the Rolling subtest and the Crayon subtests of the Prop: F test (.33 and .58, respectively) and low Cronbach’s αs on the One Hand and One Foot subtests of the Prop: JP test (.68 for both). Potential reasons for this include the fact that those subtests have fewer items as well as possible confusion related to scoring. Variations in assessment kit components, such as the weight of the test bottle and the material of the rolling surface, were also suspected as contributing factors. Additional research is necessary to enhance the psychometric properties of Prop: F and Prop: JP tests, potentially by reconsidering consistent specifications of test materials and standard testing procedures.
In a study of sensory organization of balance responses in children ages 3–6 yr, Foudriat et al. (1993) found that the predominance of visual–vestibular control of balance gives way to a somatosensory–vestibular dependence by age 3 yr; however, 6-yr-olds generally showed the greatest postural stability of any age group. Lin et al. (2013) analyzed age-related developmental factors for various SI abilities (including vestibular and proprioceptive-related abilities). The participants were divided into four age groups: (1) 3–4 yr, (2) 5–6 yr, (3) 7–8 yr, and (4) 9–10 yr. The authors found statistically significant differences in most abilities between the 3- to 4-yr and 5- to 6-yr groups; however, there were no significant differences between the 5- to 6-yr and 7- to 8-yr groups. Significant differences appeared again between the 7- to 8-yr and 9- to 10-yr groups. These findings are similar to the results of our study, indicating that vestibular and proprioceptive-related SI abilities develop rapidly from age 3, slow down between ages 6 and 8, and then reach a plateau after age 9–10. According to Peterson et al. (2006), vestibular and proprioceptive performance at around age 12 is comparable to that of adults, which is consistent with our findings: Abilities appear to plateau at this age, with no significant further increases.
The EASI platform currently provides percentile rankings that are based on the means and standard deviations for specific age and gender groups. The nonlinear model developed in this study also allows one to input the child’s age and raw scores from various assessments to generate corresponding average scores and percentile rankings for that age group. The primary advantage of this model is its ability to compare a child’s current abilities with typical age-related expectations. For example, a 9-yr-old child with postural control abilities at the 15th percentile may demonstrate performance that is equivalent to that of an average child who is age 7 yr, 1 mo. Presenting results in terms of age equivalence helps identify whether a child’s development is delayed, age appropriate, or advanced.
Human development often follows nonlinear trajectories rather than strictly linear ones. In this study, we found that scores on the six vestibular and proprioceptive tests tended to approach full scores at approximately age 12 yr, suggesting a saturation point in ability development. For data that exhibit such saturation, traditional linear regression models can result in underfitting. Although quadratic models can accommodate certain nonlinear patterns, they may overfit the data, sometimes showing a downward curve where development should plateau. The nonlinear hyperbolic model was found to be particularly valuable in this study because it is well suited to handle tests for which scores reach a saturation point. It effectively captures defining characteristics of the developmental process, such as initial levels, rates of changes during growth spurts, and maximal asymptotic levels. The EASI tests are structured so that earning full scores means a person has the functional abilities described by the test items. These tests are not intended to measure special talents, and most adults eventually reach a point where their scores no longer increase. Therefore, these tests do not represent a problem of a test ceiling effect.
Among all constructs addressed by the tests, postural control is considered a fundamental sensorimotor function; the results for the PC test showed significant development around age 7 yr. Other abilities—such as the Bal, O: M&Pr, and BI—require integration with vision and other skills, which demonstrate notable development later, around ages 8– 9 yr (de Sá et al., 2018). In the EASI proprioception test (Prop: Force and Prop: JP), postural control related not only to body position but also force perception require adjusting the amount of force based on the distance involved. The test requires motor control abilities, which mature at a later stage of development (Koitabashi et al., 2024; Smits-Engelsman et al., 2003). Scores for these abilities typically mature around age 9–10 yr.
We also used the hyperbolic model to predict the age at which children reached 90% of each test score at approximately age 12 yr. This threshold is consistent with the original intent of the EASI items, which are designed to reflect functional abilities that are expected to be mastered during typical development, not exceptional skills. These items are intended to be achieved by most individuals, including adults. For example, research has shown that the SI required to maintain balance while standing reaches adult level by age 12 yr (Peterson et al., 2006), which supports the expectation that most children will achieve near-perfect scores on these tests before that age. Thus, the EASI vestibular and proprioceptive tests are not affected by ceiling effects.
In this study, we aimed to develop an information system that, after a child’s age, gender, and assessment results are inputted, can display the expected abilities for that age and indicate the approximate age level that corresponds to the child’s actual abilities. The information system developed in this study can identify the specific age at which the average score for each item reaches 90% of the maximum, indicating the onset of performance saturation. The computer information system can then compare the assessed age with the actual age to identify developmental delays. It also can track progress after clinical intervention.
Lamash et al. (2022) were the first to examine the age-related developmental trends in EASI praxis scores. The present study is the first to demonstrate that EASI vestibular and proprioceptive scores also vary with age. By combining measurement and modeling techniques, we constructed a nonlinear hyperbolic system for age prediction that is based on measured data. Although a typically developing child might show an initial plateau, a rising slope, and a maximum asymptotic level, our study’s data, measured from age 3 yr, did not indicate an obvious initial plateau; instead, the focus was on the observed rising process, with developmental spurts from most vestibular and proprioceptive functions occurring between ages 7 and 9 yr.
Implications for Occupational Therapy Practice
The present findings have important implications for occupational therapy practice. We developed a regression model to predict total test scores on the basis of age, as illustrated in Figure 2. This allows each child to have an age-based predicted score that represents the expected average for typically developing peers. In Figure 2, the red dotted line indicates the mean score across ages. The nonlinear model offers additional advantages, including parameters that are interpretable in terms of developmental progression and that can be mapped aligned with established theories of psychological or physical growth. The nonlinear (hyperbolic) models for the six EASI vestibular and proprioceptive tests can be confidently applied to identify children with vestibular and proprioceptive difficulties. These SI challenges often affect children’s ability to engage in age-appropriate daily occupations. By using the hyperbolic model to interpret EASI vestibular and proprioceptive scores, occupational therapists can more accurately detect these sensory-based challenges and develop targeted, evidence-informed intervention plans that support participation and functional independence.
Limitations
This study has several limitations. Postrotary nystagmus is a vestibular function test within the EASI, but it cannot currently be included in the information system because its score does not directly indicate ability. Although typically developing children tend to fall within an average range, less sensitive individuals may show little or no response, whereas more sensitive individuals could exhibit prolonged nystagmus. Overcoming this limitation remains an important focus for future research.
The EASI currently is undergoing psychometric validation. Although developmental modeling is being explored concurrently, it should be approached with caution. Developing a norm-referenced model requires updated and significantly larger datasets across a broad range of age groups. The coefficients generated in the current model should be considered preliminary. To better understand age-related trends in vestibular and proprioceptive development, additional normative data from larger and more representative samples are needed.
Furthermore, one test—Prop: F—showed only moderate internal consistency. This suggests a need for further investigation into the consistency of materials used (e.g., rolling bottles, crayons) and the standardization of testing procedures.
In addition, we did not collect clinical data related to birth or early developmental history, and we did not exclude children who were typically developing themselves but had siblings diagnosed with certain developmental issues. Some vestibular and sensorimotor integration difficulties may stem from perinatal factors, such as low birth weight, prematurity, or prenatal malformations (Solan et al., 2007). Future studies should consider including early developmental, birth, and genetic history to explore potential correlations with current vestibular and proprioceptive functioning.
Conclusion
In this study, we found statistically significant age-related improvement in vestibular and proprioceptive functions, in particular in children between ages 7 and 9 yr. These findings offer valuable insights to support the future development of age-referenced norms, which can serve as benchmarks for identifying typical developmental progress.
The findings support the clinical utilities of the EASI vestibular and proprioceptive tests in identifying SI challenges. Of note is that the nonlinear hyperbolic model provides a valuable reference framework for interpreting EASI vestibular and proprioceptive scores. It enhances the precision of assessment and supports the accumulation of clinical data to inform evidence-based practice and guide long-term intervention planning.
Footnotes
Acknowledgments
This study was funded by the National Science and Technology Council (Taiwan) Grant NSTC 108-2511-H-214-001-MY2 to Shao-Hsia Chang. We thank the occupational therapists and children who contributed to the EASI norm data collection in Taiwan.