Fuzzy Sets: An application to Warnings and Instructions

Instructions and Warnings while often requiring the reader to make fairly precise sensory judgements or physical actions, yet convey these requests in the qualitative terms of common discourse, such as the phrase “fairly precise” in this sentence, or the instruction “press firmly”. The consequences of “not following instructions” can range from less than satisfactory product performance (e.g., “poor shine”) to broken equipment or even serious personal injury. The writer of instructions and warnings must know (1) how such qualitative or “fuzzy” terms will be quantitatively translated into action and (2) how to design terms (e.g. “press firmly but not hard”) to produce the desired user action. This paper describes initial work undertaken to apply fuzzy set theory to these problems and comparison of empirical definitions of a membership function.