An evaluation of the information interface in the design of computer-driven aids for expressive communication

Computer-based systems as assistive aids for expressive communication have become increasingly sophisticated. One such system, which provides great flexibility in the specification of an operational configuration and which is highly user-oriented in its design, is discussed here. In particular, attention is directed towards the relationship between the physical signals which constitute the representation of graphic-symbol communication units and the transfer of conceptual information which these symbols ultimately mediate. This relationship is investigated practically with a view to establishing a connection between operational criteria at the functional level and the supporting physical infrastructure at the computational level. This investigation leads to some conclusions not only in terms of design strategy for flexible communication aids, but points to issues of broader significance in the area of computer-based assistive devices for those with special needs.