8.3 Augmentative & Alternative Communication (AAC): Unaided to High-Tech Systems

The Augmentative & Alternative Communication (AAC) Continuum

Communication is a fundamental human right recognized under federal special education mandates (IDEA 2004) and professional standards (NBPTS Standard IV). For exceptional learners with significant speech and language impairments—including non-speaking or minimally speaking students with Autism Spectrum Disorder (ASD), cerebral palsy, developmental apraxia of speech, and severe intellectual or multiple disabilities—communication is achieved through Augmentative and Alternative Communication (AAC) systems. AAC is divided into two primary categories: unaided and aided systems.

Unaided vs. Aided Communication Systems

AUGMENTATIVE & ALTERNATIVE COMMUNICATION (AAC)

├── UNAIDED AAC (Body-Only; No External Tools)
│   ├── Facial expressions & body posture
│   ├── Natural gestures & pointing
│   ├── Vocalizations & vocal intonation
│   └── Formal manual sign systems (ASL, Signed English, Makaton)
│
└── AIDED AAC (External Equipment / Tools Required)
    ├── NO-TECH / LOW-TECH (Non-electronic, static tools)
    │   ├── Communication books / PODD books
    │   ├── Eye-gaze frames (E-Tran boards)
    │   └── PECS (Picture Exchange Communication System)
    ├── MID-TECH (Battery-operated, static display, recorded digitized speech)
    │   ├── Single-message switches (BIGmack, Little Step-by-Step)
    │   └── Static multi-cell overlay devices (GoTalk 9+, 20+, Tech/Talk)
    └── HIGH-TECH (Microprocessor dynamic display, synthesized/digitized speech)
        ├── Dedicated Speech-Generating Devices (Tobii Dynavox, PRC Accent)
        ├── Non-Dedicated Tablets (iPads with TouchChat, LAMP Words for Life)
        └── Alternative Access: Eye-tracking, head-pointing, switch scanning

• Unaided AAC Systems: Rely entirely on the user's anatomical body without external instruments or electronic equipment. Examples include facial expressions, natural gestures, idiosyncratic bodily movements, vocalizations, and formalized manual signing systems (e.g., American Sign Language [ASL], Signed Exact English). While unaided systems have the advantage of zero cost and instant portability, they require adequate motor control and demand that communication partners understand the specific signs or gestural codes.
• Aided AAC Systems: Require external physical equipment, tools, or technological hardware. Aided AAC exists across a technological spectrum spanning no-tech to sophisticated high-tech speech-generating systems.

The Aided Technology Continuum

1. No-Tech / Low-Tech: Non-electronic tools that do not require batteries or microprocessors. This includes paper-based communication books, laminated topic boards, alphabet boards, eye-transfer (E-Tran) acrylic frames, and symbol-exchange binders such as the Picture Exchange Communication System (PECS).
2. Mid-Tech: Simple, battery-operated electronic devices that feature static (unchanging) paper graphic overlays and recorded digitized speech (actual human voice recordings stored electronically). Examples include single-message switches (e.g., AbleNet BIGmack, QuickTalker), sequencers (e.g., Step-by-Step communicators for reciting lines in a school play), and multi-cell static overlay communicators (e.g., GoTalk 4+, 9+, or 20+).
3. High-Tech: Microprocessor-driven electronic systems characterized by dynamic displays (touchscreens where selecting a symbol dynamically changes the displayed screen or branches to subcategories) and high-fidelity synthesized speech (text-to-speech algorithms producing synthetic spoken output). High-tech devices are categorized into:
   • Dedicated Speech-Generating Devices (SGDs): Purpose-built, durable medical-grade equipment dedicated solely to augmentative communication (e.g., Tobii Dynavox I-Series, PRC-Saltillo Accent series).
   • Non-Dedicated Commercial Tablets: Mainstream consumer tablets (e.g., Apple iPad) loaded with specialized, research-based AAC communication software (e.g., LAMP Words for Life, TouchChat HD with WordPower, Proloquo2Go).

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The Picture Exchange Communication System (PECS)

Developed in 1985 by Lori Frost and Dr. Andrew Bondy, the Picture Exchange Communication System (PECS) is an evidence-based, low-tech augmentative communication intervention grounded in applied behavior analysis (ABA). PECS is designed to teach functional, spontaneous, self-initiated social communication to non-speaking children by capitalizing on concrete physical exchanges. PECS unfolds across six sequential behavioral phases:

The Six Phases of PECS

1. Phase I: How to Communicate (Physical Exchange): The student learns to initiate communication by picking up a single picture symbol of a highly desired item, reaching toward the communicative partner, and releasing it into the partner's open hand in exchange for the actual item. Instruction requires two adults: the Communicative Partner (who sits facing the student, holds the reinforcer, and entices the student without verbal prompting) and the Physical Prompter (who sits silently behind the student to provide physical hand-over-hand guidance, systematically fading prompts without using verbal instructions like "give me the card").
2. Phase II: Distance and Persistence: The student generalizes the communicative exchange across physical space. The student learns to retrieve the picture symbol from their communication binder, traverse across the room to locate the communicative partner, and insistently place the symbol into their hand, cultivating persistence and social initiation.
3. Phase III: Picture Discrimination: The student learns to discriminate between symbols in their communication binder:
   • Phase IIIa: Discriminating between a highly preferred item and a non-preferred/distractor item (e.g., chocolate candy vs. a sock).
   • Phase IIIb: Discriminating between two or more highly preferred items (e.g., ball vs. bubbles), confirmed through a correspondence check.
4. Phase IV: Sentence Structure: The student constructs multi-word requests using a removable plastic sentence strip. The student attaches a carrier icon (e.g., "I want") followed by the picture of the desired object, detaches the entire sentence strip, hands it to the communicative partner, and points to each icon as the partner reads it aloud.
5. Phase V: Answering "What do you want?": The student transitions from purely spontaneous requesting to responding to direct social inquiries. The partner points to the "I want" card while verbally asking, "What do you want?" using a delayed prompting hierarchy until the student immediately initiates the request upon hearing the prompt.
6. Phase VI: Commenting: The student expands beyond instrumental requesting into social discourse and commentary. The student learns to respond to diverse environmental queries (e.g., "What do you see?", "What do you hear?", "What is it?") by constructing sentence strips beginning with carrier phrases such as "I see...", "I hear...", or "It is...".

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Linguistic Architecture: Core vs. Fringe Vocabulary

A critical failure in historical AAC programming was the reliance on "noun-heavy" communication boards (e.g., walls of foods, toys, and specific classroom objects). Contemporary AAC linguistic science dictates that communication displays must be structured around the distinction between core vocabulary and fringe vocabulary:

AAC LINGUISTIC ARCHITECTURE

┌───────────────────────────────────────────────────┬───────────────────────────────────────────────────┐
│ CORE VOCABULARY (~80% of Spoken Words)            │ FRINGE VOCABULARY (~20% of Spoken Words)          │
├───────────────────────────────────────────────────┼───────────────────────────────────────────────────┤
│ - High-frequency words across all age groups      │ - Low-frequency, highly specific words            │
│ - Consistent across contexts and environments     │ - Context-dependent and topic-specific            │
│ - Mostly verbs, pronouns, prepositions, adjectives│ - Mostly concrete nouns and proper names          │
│ - Generative: enables novel sentence formulation  │ - Non-generative: cannot form functional grammar  │
│ - Examples: go, stop, want, more, help, I, you,   │ - Examples: pizza, trampoline, elephant, iPad,    │
│   not, like, open, turn, in, on, make             │   crayon, scissors, bus                           │
└───────────────────────────────────────────────────┴───────────────────────────────────────────────────┘

Because core words comprise the overwhelming majority of human discourse, an exceptional learner equipped with 50 core words can express hundreds of varied communicative intents (e.g., "Go out," "Help me," "I not like that," "Turn it on"). Conversely, a child provided only with 50 fringe nouns can do little more than request isolated objects. Modern AAC systems maintain core vocabulary in consistent motor-spatial positions across screens, capitalizing on motor planning automaticity (as seen in Language Acquisition through Motor Planning [LAMP]).

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Access Modalities & Physical Accommodations

For exceptional learners with physical and neuromotor impairments (such as spastic quadriplegia cerebral palsy), accessing an AAC device requires specialized physical accommodations:

• Direct Access: The user directly selects the target symbol using a body part or physical extension:
  • Touch / Direct Selection: Finger pointing or physical touch on a screen or board.
  • Physical Adaptations: Keyguards (acrylic grids placed over dynamic screens to prevent unintended adjacent touches), styluses, or weighted hand splints.
  • Head Trackers: Optical sensors detecting a reflective dot placed on the student's forehead or glasses to control an on-screen mouse cursor.
  • Eye-Gaze / Eye-Tracking Systems: Infrared cameras mounted to the base of an SGD that track the user's corneal reflections and pupil movements, allowing the user to select symbols simply by fixating their gaze (dwell time) or blinking.
• Indirect Access (Scanning):
  • Used when severe motor limitations prevent direct selection. The AAC system automatically or manually steps through items, rows, or quadrants on the display screen. When the desired symbol is highlighted, the student activates an adaptive physical switch (e.g., jelly bean switch, proximity sensor, sip-and-puff switch, or eyebrow switch) with whatever voluntary muscle movement they can reliably control.
  • Partner-Assisted Scanning (PAS): A low-tech method where a human communication partner systematically points to or reads symbols aloud, and the learner signals acceptance through a designated movement (e.g., eye blink, vocalization, or head nod).

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Partner Modeling & Systemic Implementation

The most sophisticated AAC hardware is worthless if the student's communicative environment is unsupportive. AAC research demonstrates that the primary reason for device abandonment (which occurs in up to 30-50% of cases) is inadequate communication partner training and lack of immersion.

Aided Language Stimulation (ALS) / Aided Language Input

Aided Language Stimulation (ALS) is the gold-standard, evidence-based instructional methodology for teaching AAC. Grounded in the principle that children acquire natural spoken language because the adults around them model spoken language for thousands of hours before expecting verbal output, ALS dictates that communication partners must speak and simultaneously point to corresponding symbols on the student's AAC system.

Key rules of Aided Language Stimulation:

1. Model Without Demanding Output: The adult models AAC throughout the day without requiring the child to imitate or press the buttons.
2. Target One Step Above: Model at the student's current linguistic level plus one word (e.g., if the student is communicating with single words like "eat", the partner models "want eat" or "eat apple").
3. Ubiquitous Access: The AAC device must be physically accessible to the student at all times across all settings (classroom, playground, cafeteria, bus, home). Restricting access or "saving the device for speech therapy" is a severe violation of FAPE and communicative integrity.

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Comparative Framework: AAC Modalities & Implementation Parameters