Cognitive scientist George Kelly suggests that knowledge representation is based on a geometry of psychological space. Unlike the geometry of areas or of lines, there are no distances in this geometrically structured world. Dichotomies have differentiating and integrating functions through which humans intervene in their world. Dichotomies allow us to distinguish between and ascribe integrity to incidents that would otherwise be imperceptible because they are too highly fragmented or homogeneous. Angles are represented by contingencies or overlapping frequencies of incidents.
Iconic Representations are the sensory projections of objects and events.
Categorical Representations are learned and innate feature-detectors that distinguish object and event categories from their sensory projections. Category Names serve as the atomic symbols for a third representational system, Symbolic Representations, which underlie language. Elementary symbols are used to name these object and event categories on the basis of their categorical representations. These symbols are then combined into strings expressing propositions about more abstract categories. These symbolic form of representation makes it possible to name and describe our environment in terms of categories, their relationships and features.