The Bell Curve
Have we built our society on too narrow a base? The figure I reach for most.
What it is
This is the illustration I reach for most. It is a bell curve over the population: most individuals sit in the centre, while some are out on the edges, excluded or marginalised. This way of thinking is the foundation for how accessibility is conceptualised in standards and guidelines.
I use it to make a point that runs against that picture. The centre is not where we learn the most about the flexibility human diversity needs. It is at the outer edges, among the people called “extreme users”, “edge cases” or “fringe cases”, that we find those who can tell us most about what they struggle with and what supports them. That is also where the current non-users are. As Dan Formosa puts it in the documentary Objectified: “If we understand what the extremes are, the middle will take care of itself.”
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References
- Hedvall, P.-O., Ståhl, A., & Iwarsson, S. (2025). Accessibility, usability and universal design – still confusing? Harmonisation of key concepts describing person-environment interaction to create conditions for participation. Disability and Rehabilitation, 1–10. https://doi.org/10.1080/09638288.2025.2491831
- Hedvall, P.-O., Price, M., Keller, J., & Ericsson, S. (2022). Towards 3rd Generation Universal Design: Exploring Nonclusive Design. UD2022, Italy.
- Documentary: Objectified (dir. Gary Hustwit, 2009). Freely viewable at documentaryheaven.com/objectified.
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