ABSTRACT
This chapter explains about the stimulus error Paolo Bozzi struggles with a net of exquisitely conceptual issues concerning perception and its objects. In a rather classical way, he highlights six steps in the causal pathway leading from the physical object to the experience thereof; the physical object itself, an event in the informational medium, the proximal stimulus, and the flow of information in the brain, its processing, and the experience itself. The experimenter retaliates by presenting the E. H. Adelson demonstration, a picture of an object casting a shadow on a grey-and-white chessboard. This time the subject is dumbfounded: she may be completely unwilling to say that a white square in the shade matches a grey square in full light. The conceptual power of the “stimulus tool” bears fruits: Adelson’s “illusion” is not an illusion: the colours of the two different squares are seen as different, as they are.
