주권 Relationally Extended Functional Ability

[안규환]

This is a comprehensive English adaptation of your research draft, structured for submission to high-impact journals such as Disability and Rehabilitation or Journal of Rehabilitation Medicine. It has been written to be academically rigorous yet clear enough for a broad professional audience.

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Relationally Extended Functional Ability: Integrating ICF, ICHI, and Rasch Modeling in a Single-Case Ecological Study of Disability in Daily Life

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1. Abstract

Purpose: This study challenges the traditional view of functional ability as an isolated individual trait. Instead, it proposes a reconceptualization of ability as a relationally constructed system mediated by tools and social support. By integrating the International Classification of Functioning, Disability and Health (ICF), the International Classification of Health Interventions (ICHI), and an adapted Rasch modeling framework, this research analyzes the moment-to-moment dynamics of “ability” in a real-world ecological setting.

Methods: A mixed-methods single-case ecological study was conducted using continuous data from a participant’s daily life, including mobility, self-care, social participation, and digital tool usage. Activities were coded using the ICF framework, while interventions and support systems were categorized using the “means-based” classification of the ICHI. To capture the relational nature of ability, a modified Rasch model was applied to estimate functional capacity (θθ) as a dynamic interaction between the person, technology, and social environment.

Results: The analysis revealed that functional ability is not static but fluctuates based on environmental and relational inputs. The participant’s individual ability (θθ) increased from approximately +1.3 in the morning to +2.2 by the end of the day as they engaged with cognitive tools. Notably, when collaborating with a spouse, the combined “team ability” reached θteam≈+2.6θteam​≈+2.6. Despite physical limitations, complex tasks (e.g., high-level decision-making) were successfully navigated through this extended system.

Conclusion: Functional ability should be redefined as a relational, system-based construct. The integration of ICF and ICHI with Rasch modeling provides a robust framework for capturing real-world adaptive functioning. This shift has significant implications for person-centered care, assistive technology design, and rehabilitation strategies.

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2. Introduction

Traditional models of disability have long viewed “ability” as an internal, intrinsic property of the individual. While modern frameworks like the ICF (International Classification of Functioning, Disability and Health) have shifted the focus toward the interaction between the individual and their environment, many operational tools still struggle to capture the fluid, mediated, and relational nature of daily life.

In reality, a person’s capacity to perform a task is rarely a “solo” endeavor. It emerges from a complex web of social relationships, technological aids, and environmental affordances. This study introduces the concept of Relationally Extended Functional Ability. We argue that ability is not something a person “has” in isolation, but something that “emerges” from a system. By synthesizing ICF (status), ICHI (means/interventions), and Rasch Modeling (measurement), we aim to provide a more accurate map of how people with disabilities navigate and thrive in complex ecological settings.

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3. Methods

3.1 Study Design

This research utilizes a single-case ecological study design. This approach prioritizes “ecological validity”—observing phenomena in the actual environment where they occur—to capture the “lived experience” of disability in real-time.

3.2 Data Collection and Sources

Data was synthesized from multiple streams to ensure a holistic view of the participant’s day:

• Narrative Self-Reports: Continuous logs of activities and feelings.
• Contextual Data: Images of gardening, receipts, and documents.
• Behavioral Records: Logs of mobility, service utilization (e.g., transportation), and decision-making processes.
• Digital Interaction Logs: Records of interactions with AI tools (e.g., GPT) used for cognitive support and problem-solving.

3.3 Classification Frameworks (ICF & ICHI)

• Expanded ICF Coding: Activities were categorized into Body Functions (b), Activities (d), and Environmental Factors (e). We extended this to include “meaning-based” dimensions to capture the psychological value of activities.
• Extended ICHI Means Model: Interventions were categorized not just as medical treatments, but as “means” of functioning. This included biological (medication), technological (AI/GPT), social (spousal support), and environmental (gardening/nature) interventions.

3.4 The Adapted Rasch Model

The core innovation of this study is the modification of the Rasch model. Traditionally used to measure latent traits, we adapted the model to treat functional ability (θθ) as a function:
θ=f(Individual Capacity, Tools, Relationships, Environment)θ=f(Individual Capacity, Tools, Relationships, Environment)
This allows us to mathematically represent how a person’s “score” increases when they use a tool or work with a partner.

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4. Results

4.1 The Spectrum of Daily Activities

The participant engaged in a diverse range of activities, from basic self-care (d5201) and gardening (d630) to high-level cognitive tasks such as digital problem-solving (d175) and policy-related decision-making (d177). This spectrum highlights that physical disability does not preclude participation in complex social and intellectual roles.

4.2 The Dynamics of Functional Ability (θθ)

The Rasch analysis demonstrated that θθ is a moving target:

• Morning Baseline: Due to factors like sleep deprivation, the initial ability was measured at θ≈+1.3θ≈+1.3.
• Mid-day Progression: As social engagement and mobility increased, θθ rose to +1.8.
• System Synergy: At the peak of the day, utilizing digital tools and integrated decision-making, the participant reached θ≈+2.2θ≈+2.2.
• Relational Peak: When performing tasks as a “couple system” (e.g., navigating complex logistics with a spouse), the ability soared to θteam≈+2.6θteam​≈+2.6.

4.3 Performance in High-Difficulty Tasks

The study observed the successful completion of “high-beta” tasks (tasks with high difficulty ratings). For example, booking high-speed rail (KTX) tickets (β≈+2.2β≈+2.2) and analyzing pension policies (β≈+1.8β≈+1.8) were achieved despite physical barriers. This suggests that the system compensates for individual impairment, allowing for high-level outcomes.

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5. Discussion

5.1 Ability as a Relational Construct

The findings suggest a paradigm shift from “Individual Ability” to “Relational System Ability.” When we measure what a person can do, we must measure the entire system they are part of. A person plus a wheelchair, or a person plus an AI, or a person plus a spouse, constitutes a new functional unit.

5.2 The Role of AI as a Cognitive Prosthetic

A significant finding was the role of GPT and digital tools. These did not just provide information; they acted as a “cognitive extension.” They structured complex tasks and provided decision-making support, effectively functioning as a “digital ramp” for the mind, much like a physical ramp works for a wheelchair.

5.3 Implications for Rehabilitation

Rehabilitation should move beyond just “fixing the body.” It should focus on:

1. Relationship Facilitation: Strengthening the social “team.”
2. Tool Integration: Training in digital and assistive technologies.
3. Meaning-Making: Ensuring activities provide a sense of purpose, which in turn drives functional engagement.

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6. Conclusion

This study provides empirical evidence that functional ability is a dynamic, system-generated phenomenon. By integrating ICF and ICHI with Rasch modeling, we have moved toward a more precise measurement of how people actually live with disability.

The ultimate takeaway of this research is: Ability is not a possession of the individual; it is an emergence of the system. Future rehabilitation and policy must focus on optimizing these systems to ensure that every individual can reach their maximum potential within their unique ecological context.

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Keywords: ICF, ICHI, Rasch Model, Disability, Relational Ability, Assistive Technology, Rehabilitation, Ecological Study.

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