Understanding road signs

In this paper, we propose a three levels framework that allows accounting for the understanding of road signs. We consider that a road sign is (1) the iconic transcription of (2) a legal message about categories that is displayed and has to be interpreted (3) in context. Whereas categorization is the basic process that determines decision-making, results of two experiments show that road signs, as well as the generative grammar they are based on, are not so well know by road users. Results also show that natural categories (categories used by drivers) do not match legal categories (categories defined in legal texts about driving). Even if people and laws agree on words, they do not agree on the intensions and extensions of the categories tagged by words. Finally, we discuss about the critical role played by context (situational/environmental one and task-context) in the processing of road signs interpretation.