In this thesis an Instant Messaging application named FlexiChat, suited for adolescents in special needs school, has been developed and evaluated. Communication is based on symbols instead of text and uses the Flexiboard as main input device to accommodate the cognitive limitations of the user group. The application has been based on previous research and guidelines for designing for cognitive limitations.

The users participating in the evaluations consisted of adolescents with limited cognitive abilities and various diagnostic labels, such as autism spectrum disorder, down syndrome and cerebral palsy. The findings have been compared to results from earlier research made on a similar program named SymbolChat.

The findings demonstrates that the accessibility of Instant Messaging can be increased by taking the cognitive limitations of this user group into consideration. The FlexiChat prototype proved to be a fast and fun way to interact with others and all participants stated they would like to continue using it. In addition, the evaluations showed that the majority of the participants preferred the Flexiboard over a conventiona lkeyboard, which clearly discloses its potential as an assistive device.