10.3 Intervention & Implementation for AAC

10.3 Intervention & Implementation for AAC

Augmentative and Alternative Communication (AAC) clinical intervention involves the systematic assessment, design, feature matching, and implementation of communication systems for individuals with severe expressive communication disorders. Guided by the Participation Model (Beukelman & Mirenda), AAC clinical management aims to eliminate participation barriers, enhance functional autonomy, and provide multimodal tools spanning unaided (gestures, sign language) and aided (low-tech boards, high-tech speech-generating devices [SGDs]) modalities.

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1. The Participation Model Framework & Barrier Assessment

The Participation Model provides a structured clinical framework comparing an individual's communication participation in natural environments against that of neurotypical, same-age peers.

                  ┌──────────────────────────────────────────────┐
                  │          Participation Model Framework       │
                  └──────────────────────┬───────────────────────┘
                                         │
        ┌────────────────────────────────┴────────────────────────────────┐
        ▼                                                                 ▼
┌───────────────┐                                                 ┌───────────────┐
│ Opportunity   │                                                 │ Access        │
│ Barriers      │                                                 │ Barriers      │
└───────┬───────┘                                                 └───────┬───────┘
        │                                                                 │
  ┌─────┴───────────────────────────────┐                   ┌─────────────┴─────────────┐
  ▼                                     ▼                   ▼                           ▼
┌───────────────────┐ ┌───────────────────┐ ┌───────────────────┐       ┌───────────────────┐
│ Policy & Practice │ │ Attitude, Knowledge│ │ Motor & Access    │       │ Sensory, Cognitive│
│ Barriers          │ │ & Skill Barriers  │ │ Capability Limits │       │ & Linguistic Limits│
└───────────────────┘ └───────────────────┘ └───────────────────┘       └───────────────────┘

Identifying Communication Barriers

1. Opportunity Barriers: External constraints imposed by society, institutions, or communication partners:
   • Policy Barriers: Legislative or administrative mandates restricting AAC device funding or access (e.g., school rules prohibiting device transport home).
   • Practice Barriers: Established routines or habits within a facility (e.g., staff turning off SGDs during meal times).
   • Attitude Barriers: Negative or limiting beliefs of communication partners regarding an individual's communicative potential.
   • Knowledge & Skill Barriers: Lack of partner technical expertise in programming, managing, or modeling AAC strategies.
2. Access Barriers: Limitations in the individual's current operational, physical, sensory, cognitive, or linguistic capabilities.

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2. Feature Matching & Access Mechanics

Feature Matching is the process of matching an individual's specific communication, cognitive, motor, visual, and sensory capability profile with appropriate AAC system features.

Access Selection Modes

• Direct Selection: The individual directly indicates a target symbol using a physical body part or technology interface:
  • Physical Touch: Touchscreen activation using fingers, hand, or toe.
  • Head-Pointer / Stylus: Physical or mechanical extension for individuals with reduced trunk control but adequate neck movement.
  • Eye-Gaze Tracking: Infrared cameras track pupil position and corneal reflections. System activation occurs via dwell time (e.g., maintaining gaze focus on a target icon for $300\text{ to }500\text{ milliseconds}$) or eye blinks.
• Indirect Selection / Scanning: Used when physical motor impairments prevent direct target selection. The system presents items sequentially, and the user activates a switch when the target item is highlighted:
  • Scanning Patterns: Linear (item by item), Row-Column (highlights entire rows sequentially, then individual items within the selected row), or Quadrant/Block.
  • Control Techniques:
    • Automatic Scanning: System automatically advances through items; user hits switch to select.
    • Step Scanning: User repeatedly activates switch to advance cursor, pausing or hitting a second switch to select.
    • Inverse Scanning: User holds switch down to advance cursor; releasing switch selects target.

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3. Symbol Systems & Vocabulary Architecture

Symbol Iconicity Continuum

AAC symbols exist along a continuum of iconicity (the visual relationship between a symbol and its referent): $\text{Transparent (High Visual Clarity)} \longrightarrow \text{Translucent (Clear Once Explained)} \longrightarrow \text{Opaque (Arbitrary / Abstract)}$

Core vs. Fringe Vocabulary Architecture

An evidence-based AAC system balances core and fringe vocabulary to enable flexible, generative communication across diverse social contexts:

Display Layout Organizations

• Syntactic / Fitzgerald Key: Icons arranged left-to-right matching spoken word order, color-coded by speech part (Nouns = Yellow, Verbs = Green, Descriptors = Blue, Pronouns = Orange).
• Visual Scene Displays (VSDs): Contextually rich photographs or digital images representing meaningful real-world scenes (e.g., a photo of a kitchen) with embedded interactive "hotspots." Highly effective for young children and individuals with severe chronic global aphasia or traumatic brain injury.

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4. Evidence-Based AAC Implementation Strategies

Aided Language Input (ALI) / Partner Augmented Input (PAI)

• Mechanism: Communication partners point to AAC symbols on the user's system while simultaneously speaking during natural daily interactions.
• Rationale: Language development requires immersion. AAC users cannot be expected to expressively communicate using AAC symbols if they never observe communication partners modeling communication through that same modality.

Least-to-Most Prompting Hierarchy

To promote independent spontaneous communication without creating prompt dependency, clinicians systematically execute a least-to-most prompting sequence:

1. Environmental Arrangement & Natural Cue: Setting up an engaging activity with missing items.
2. Expectant Pause: Maintaining open body posture and expectant eye contact for $5\text{ to }10\text{ seconds}$.
3. Indirect Visual / Verbal Prompt: Pointing toward the device or asking "What do we need?"
4. Open-Ended Question: Asking "What do you want to say?"
5. Partial Model: Pointing to the general location or category key on the device.
6. Full Model / Physical Assistance: Demonstrating the exact icon sequence on the device.

Language Acquisition through Motor Planning (LAMP)

• Population: Designed primarily for non-verbal children with Autism Spectrum Disorder (ASD) or complex developmental disabilities.
• Core Principles:
  1. Readiness to Learn: Regulating motor sensory arousal.
  2. Shared Engagement: Following the child's motivation.
  3. Consistent Motor Pattern: Every word is accessed via a unique, non-changing motor key path on a dynamic display SGD. Button locations never change across pages to build motor automaticity (similar to touch-typing).
  4. Auditory Feedback: Immediate voice-output confirmation upon button activation.
  5. Natural Consequences: Immediately fulfilling the child's communicative request.

Picture Exchange Communication System (PECS)

PECS is a 6-phase manual picture exchange protocol targeting functional communication initiation:

• Phase I (Physical Exchange): Initiating exchange of a single picture for a desired item.
• Phase II (Distance & Persistence): Traveling to a communication binder, pulling a picture, and seeking out a partner.
• Phase III (Picture Discrimination): Discriminating between preferred and non-preferred icons.
• Phase IV (Sentence Structure): Using an "I want" strip paired with a picture icon.
• Phase V (Answering Questions): Responding to "What do you want?"
• Phase VI (Commenting): Spontaneously answering "What do you see/hear?"

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5. Clinical Pathways for Progressive Conditions (ALS)

In neurodegenerative conditions such as Amyotrophic Lateral Sclerosis (ALS), proactive AAC intervention occurs across distinct clinical stages:

• Stage 1 (Preserve Natural Speech): Acoustic monitoring of speech rate ($<120\text{ words/minute}$) and speech intelligibility ($<90%$ on sentence tests).
• Stage 2 (Voice & Message Banking): Digitally recording custom phrases ("voice banking") and functional messages ("message banking") prior to severe bulbar deterioration.
• Stage 3 (Introduce Augmentative Systems): Selecting low-tech backup boards and high-tech SGDs with direct touch while limb function persists.
• Stage 4 (Transition to Alternative Access): Implementing Eye-Gaze Tracking SGDs as bulbar and spinal motor function declines, ensuring uninterrupted communication access.