Augmentative and alternative communication systems: principles of engineering and design

Abstract

Augmentative and alternative communication symbol sets for cerebral-palsied are divided into two classes: pictorial and symbolic ones. Pictorial sets represent referents by physical analogy, which affords them high iconicity and denotative clarity, so that children, foreigners and the brain-lesioned can understand, learn and remember their meaning with relative ease. Yet, they can represent only meanings which are capable of being concretely imagined and depicted. On the other hand, symbolic sets represent referents via arbitrary conventions using specific recombinative and syntax rules, which allows them to represent virtually any concept, irrespective of its concretude. Yet, in consequence, they tend to be denotatively opaque. Pictorial sets include Maharaj’s Pictogram-Ideogram Communication Symbols, and Johnson’s Picture Communication Symbols. Symbolic sets include Blissymbols and sign systems based on signs from sign languages for the deaf. These different symbol sets have been computerized using multimedia resources in order to allow on line and pre-stored communication, both face-to-face and at a distance via netware. The paper discusses aspects pertaining to the engineering and design of the systems, as well as to their clinical use. It presents a system for teaching Blissymbols to the cerebral-palsied, the efficacy of which is experimentally analyzed in a second study of this series.