Manipulation of Pushbuttons and round Rotary Controls

This study focuses on the manipulation of pushbuttons and round rotary controls on consumer products in practice. It shows that these controls are operated in many different ways. The majority of the observed manipulations is applied both by physically impaired and non-impaired users. Variation occurs in both groups. However, variation which occurs in one group only, almost always occurs in the impaired group. People experiencing operational difficulties used hardly any new types of manipulation compared to smooth operation - that is when no difficulty is experienced in reaching a control, gripping it and exerting the required force. These findings suggest that operational difficulties function as incentives urging users concerned to resort to abilities which otherwise they would not have to draw on, rather than as constraints. From a design point of view the findings indicate that people facing difficulties in the use of everyday products would benefit from multi-operable controls, that is with a great degree of freedom for manipulation.