Symbols, Symbols What to use????
Clinical Scenario • Why do Speech Pathologists make use of graphic symbols? • Graphic symbols may take many forms
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?
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 Group Natalie Albores Alana Bain Anna Bech Lauren Chaitow Mary-ann Dowsett Haley Gozzard Jenny Lee Cecillia Rossi Nitha Thomson David Trembath Angela Vass Jenny Wood