Basic features in vision. An analysis of constraints on perceptually relevant sensory properties.

The notion of a "primitive" or "basic feature" plays a central role in the study of the functioning of perceptual systems. On the one hand it is used to determine the class of properties of the sensory stimulation to which perceptual processing applies in order to yield complex percepts. On the other hand, it allows to build cross-level explanatory links between perceptual phenomena at different levels of analysis (such as neurophysiological studies, behavioral studies and phenomenology). The goal of this work is to show to what extent the notion of a basic feature is "theory-laden". By reviewing reference philosophical works and recent empirical contributions, this work aims to articulate the different criteria adopted in the literature to frame the notion of a basic feature, to shed light on inconsistencies in its use and to address some major theoretical issues deriving from the adoption of different criteria.