Symbols, SymbolsWhat to use????

Clinical Scenario

Why do Speech Pathologists make use of graphic symbols?

Graphic symbols may take many forms

baby

High degree of resemblance Abstract

How our question developed?

A member’s personal experience

She asked Why? What is the evidence for this?

Clinical Question

In people who use AAC are coloured photographs easier to comprehend than line

drawings?

Level of evidence Study design Number of articles

3ii Narrative reviews 2

4 Case series 2

Key Findings

Evidence found of lower level – suggestive only

Population included in studies: individuals who were basically non-verbal and had intellectual disability (varying /severe); autism

Finding (cont.)….

Sevcik & Romski (1986) 8 participants between ages of 9 -22years – all had

severe intellectual disability Participants with functional language skills were able to

match objects to photographs and line drawings. They performed better on matching tasks than those with non-functional language skills

Participants with no functional language and limited comprehension of words could match objects to photos but not objects to line drawings

Findings (cont.)…

Mirenda and Locke (1989) Study on symbol transparency

40 participants; non-verbal with varying degrees on intellectual disabilities; age range 4 – 21; “non speaking”

A greater number of non-verbal people in the study identified photographs more easily than a range of symbols and line drawings

Mirenda an Locke (cont.)

Included 8 participants with severe intellectual disabilities who had poor comprehension of spoken language. None could match non- identical objects, only 3 able to match photographs to objects and only 1 could match line drawings to objects. This group’s performance was much worse than that of participants with functional language

Finding (cont.)…

Kozleski (1991b) compared acquisition rates of a variety of abstract to more iconic symbols, including coloured photographs and line drawings, for requesting function across four individuals with autism: fewer sessions were needed for highly iconic symbols.

Clinical Bottom Line There is insufficient high level evidence to

conclusively inform choice of one graphic symbol set over another.

Some minimal level of language skill may make the use of certain symbol types easier to learn

Consider CAT limitations

CAT Limitations

Clinical question very narrow

Our inclusion/exclusion criteria – did we restrict ourselves too much?

Recognition of pictures and using pictures as symbols are different skills

Clinical implications

In absence of strong evidence

Monitor the integrity of our intervention

Define interventions in observable terms

Outcome measures

Data collection sheets

Possible other variables to consider when people are learning to use picture symbols

Spoken word comprehension

Reinforcement value

Symbol experience

Understanding of intent

Setting

(cont.)

Instruction

Support

Generalization

Available resources

Stakeholders

References Sevcik, RA and Romski, MA (1986). Representation matchings

skills o persons with severe retardation. Augmentative and Alternative Communication. 2(4), 160-164

Mirenda and Locke (1989). A comparison of symbol transparency in non-speaking person with intellectual disabilities. Journal of Speech and Hearing Disorders. 54, 131-149.

Schlosser, RW and Sigafoos, J (2002). Selecting graphic symbols for an initial request lexicon: Integrative review. Augmentative and Alternative communication. 18, 102-123

Stephenson (2009). Iconicity in the Development of Picture Skills: Typical Development and Implications for Individuals with Severe Intellectual Disabilities Augmentative and Alternative Communication. 25 (3), 187-201

AAC EBP GroupNatalie AlboresAlana BainAnna Bech Lauren ChaitowMary-ann DowsettHaley GozzardJenny LeeCecillia RossiNitha ThomsonDavid TrembathAngela VassJenny Wood