The needs of blind and visually impaired users are seriously under-investigated in CSCW. We review work on assistive interfaces especially concerning how collaboration between sighted and blind users across different modalities might be supported. To examine commonly expressed design principles, we present a study where blind and sighted persons play a game to which the former has an auditory interface, the latter a visual one. Interaction analyses are presented highlighting features of

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... e design, talk and gesture which are important to the participants' abilities to collaborate. Informed by these analyses, we reconsider design principles for cooperative interfaces for the blind. Categories and Subject Descriptors H.5.1 [Multimedia Information Systems]:-audio input/output, evaluation/methodology. H.5.2 [U s e r I n t e r f a c e s ]:-a u d i t o r y ( n o n -s p e e c h ) feedback, evaluation/methodology, theory and methods, user-centred design.