Selection of appropriate vocabulary is a key consideration and can lead to greater intervention success and decreased likelihood of abandonment of the AAC system. The SLP considers the personal preferences and needs of the individual for communicating with family members and other communication partners (e.g., in social contexts, academic settings, medical settings, vocational settings, etc.) and makes all efforts to use vocabulary that is specific to the individual and consistent with his or her language, age, culture, and personal preference. Nouns tend to dominate vocabulary sets for AAC users (Dark & Balandin, 2007); however, the inclusion of verbs and other parts of speech can increase AAC acceptance and use (Adamson, Romski, Deffebach, & Sevcik, 1992).
Vocabulary is often divided into two categories: core and fringe (or “extended”). Core vocabulary consists of high-frequency words that make up about 80% of the words used by most people every day. Core vocabulary contains mostly pronouns, verbs, descriptors, and question words (Witkowski & Baker, 2012). English language learners use a comparable amount of core vocabulary as do native English speakers (Boenisch & Soto, 2015). Fringe vocabulary consists of lower-frequency words – mostly nouns – which tend to be context specific. Combining core and fringe vocabulary can increase the frequency of AAC use (Buekelman, McGinnis, & Morrow, 1991; Yorkston, Dowden, Hosinger, Marriner, & Smith, 1988).
Symbols are used in AAC to represent objects, actions, concepts, and emotions. They can include drawings, photographs, objects, facial expressions, gestures, auditory symbols (e.g., spoken words), or orthography (i.e., alphabet-based symbols).
Iconicity refers to the association made between a symbol and its referent (Schlosser, 2003). Iconicity varies along a continuum, based on how easily the meaning of the symbol can be guessed.
• Transparent symbols are at one end of the iconicity continuum and are readily guessable in the absence of the referent.
• Opaque symbols are at the other end of the continuum and are not readily guessable, even when the meaning of the symbol is known.
• Translucent symbols lie between the two extremes of the continuum. The meaning of the referent may not be obvious, but the relationship between symbol and referent is more obvious when additional information is provided (Fuller & Lloyd, 1991).
Iconicity directly affects the communicator’s efficiency and effectiveness, especially with regard to untrained or unfamiliar communication partners. High iconicity (i.e., displaying the symbol along with the written word) can help communication partners learn and interpret symbols, particularly if no voice output is available (Wilkinson & McIlvane, 2002).
There are three common ways that symbols are used to represent language; these are known as language representation methods (LRMs). A person who uses AAC may use a single LRM or a combination of LRMs, depending on preference and the functionality of the system. The following three LRMs are commonly used in AAC systems:
• Alphabet-based methods use traditional orthography (spelling) and rate enhancement techniques such as word or phrase prediction.
• Single-meaning messages use graphic symbols (e.g., photographs, drawings), each of which represents one word or message (e.g., touching the picture of the toilet indicates one’s need to go to the bathroom).
• Semantic compaction (Minspeak ®) is based on the concept of multiple-meaning iconic encoding; it combines picture symbols (icons) in various prescribed sequences to form words or phrases. Because a single icon can be associated with multiple meanings, a relatively small set of icons can be used to create many words and phrases. For example, frog can refer to the following concepts: “frog,” “green,” “jump,” and “water.” Pairing frogwith different symbols can communicate these various concepts—Frog + Rainbow = Green; Frog + Arrow = Jump; Frog + Cup = Pond (Glennen, 1997).
Symbols are a dynamic part of AAC intervention. A person’s spoken vocabulary will change based on his or her age, communication partner, language development, environment, mood, and context. The symbols used in an AAC system should allow for the same change and flexibility. Symbols are not universal across cultures. It is important to find symbols that are relevant to the individual and his or her community.
Symbol selection is also based on the person’s ability to access, recognize, and learn that symbol’s meaning. For example, a person with visual deficits will need a symbol that is modified to be viewable or that is accessible via other sensory modes such as listening or touch.
Symbol organization on an AAC system affects the individual’s ability to communicate effectively and efficiently. It plays a role in language learning and development, and it needs to be customized and modified throughout the user’s time with the AAC system (Beukelman & Mirenda, 2013).
The way in which symbols are presented on an AAC system is referred to as the display. Different encoding options (e.g., alphanumeric, numeric, iconic, alphabetic, and color) are sometimes used to organize displays. Displays can be static (fixed), dynamic (changes based on user actions), or hybrid (a combination of static and dynamic).
- Symbols remain in a fixed location.
- Most common in communication board or low-tech SGDs.
- There is a finite number of symbols/messages.
- User may have multiple fixed displays (e.g., multiple pages in a communication book).
- Electronic—selection of one symbol automatically activates change in symbol set.
- Often arranged by large category first, then broken down to more specific vocabulary items.
- With use of multiple-meaning icons, selection of one icon may prompt display of other related icons.
- Static/fixed display with dynamic component (e.g., alphabet board or keyboard with word prediction; grid display that opens new page following user selection of a symbol).
A visual scene is a view of an environment consisting of drawings, photographs, and/or virtual environments organized in a meaningful way. Visual scenes can be used to represent situations, routines, places, or experiences. They can be presented via fixed or dynamic displays (Beukelman & Mirenda, 2013). Elements within the visual scene function as hotspots that trigger message output when selected.
For beginning communicators (e.g., young children or older individuals who are at early functioning communication stages), visual scenes may be easier to learn and use than grid displays. (For more details about visual scene displays and an example, see Tuthill, 2014.)
Symbol Display Organization
Most AAC systems, with the exception of visual scenes, are presented in a grid format. The organization of vocabulary, symbol size, and number of symbols on the grid is individualized and determined by the type of display, the type of symbol, and the visual acuity, communication and cognitive skills, integrated sensory system, and motor control of the individual.
Semantic–syntactic displays organize vocabulary based on parts of speech and syntactic framework. Symbols are laid out according to spoken word order and print orientation, and they vary depending on the language used (e.g., left-to-right or right-to-left). Semantic–syntactic displays are useful for adults with relatively intact language (e.g., individuals with ALS) or language learners, and they can facilitate efficient production of grammatically complex messages.
Taxonomic displays group symbols according to semantic category (e.g., people, places, feelings, actions). Typically developing children begin to find this type of grouping helpful at around age 6–7 years, so this strategy may not be appropriate for individuals with complex communication needs who are developmentally younger than 6 years of age (Buekelman & Mirenda, 2013). Use of taxonomic displays for persons with aphasia can add to the cognitive and linguistic load and may lead to increased errors and slower response time (Petroi, Koul, & Corwin, 2011).
Activity grid displays (also known as “schematic grid layouts”) organize vocabulary by event schemes, routines, or activities. Each page or display includes activity-specific vocabulary and may be further organized by part of speech (e.g., nouns, verbs). Activity grid displays can increase participation and syntactic development by encouraging use of multiword combinations (Drager, Light, Speltz, Fallon, & Jeffries, 2003). Users may be able to navigate independently from one activity display to another, or they may rely on a facilitator or communication partner to provide the appropriate activity display for a given situation. Context-based displays are similar to activity grid displays but are designed for a particular (usually frequent) context or environment, allowing for greater generalization than vocabulary designed around a single, specific activity.
Extracted from: ASHA