Human Variability and Ergonomic Design.

Analysing in an anthropological perspective the interaction processes between people and technologies in different life and work activities, it comes out the need to consider all the social, cultural and physical aspects that mark categories of persons or well defined human groups. Such aspects can be declined through a series of characters that present a considerable variability, that it is necessary to take into account in the design and testing of every system for satisfying the largest number of people. The prescription of the article 28 of legislative decree 81/2008 refers clearly to this concept, as it demands to examine all workers safety and health risks and also those related to gender differences, age and other countries of provenance. However, such decree, that states the need to apply the ergonomic principles, concerns just the workplaces and therefore tends to protect only the working-age population. The ergonomic design involves all the interactions of people with the built environment, and must consider all the possible users categories, also of special demographic groups, as children and elderly, that show a huge variability related to growth and aging processes. An effective user-centred design requires to consider the human variability in all the development phases of a system, taking into account the characteristics of the most possible users in the phases of system definition and conceptualization and using representative subjects of that variability in the testing phases.