An apparently ordinary interaction can become difficult under a different routine or constraint. Including varied participants can expose assumptions that a narrow research group leaves unchallenged.
IDEO.org's Extremes and Mainstreams method considers people across different patterns of use. IDEO.org Design Kit — Extremes And Mainstreams.
Choose relevant differences
For a display-character project, variations in available space or handling routines may be more useful than an arbitrary demographic split. Explain why the selected difference matters to the research question.
Avoid universalising the finding
An unusual case can reveal a valuable design issue without establishing how common it is. Preserve that distinction when prioritising the response. Additional research may be needed to understand prevalence, feasibility or the effect on other users.
Source reviewed 25 October 2026. Interpretation and original diagrams: PLUSHIP / Qunhe. Examples are illustrative.
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