Formal Models for Cognition - Taxonomy of Spatial Location Description and Frames of Reference

Language uses location description with respect to spatial frames of reference. For the transformation from a visual perception to the relative expression the reference frames must fix three parameters: • origin (e.g., the speaker, an object, another person), •orientation (e.g., the axial frame of the speakers, of the addressee, of another object), •handedness of the coordinate system (same as a person's or inverse). These parameters characterize a reference frame. The paper describes the methods used in the English language and proposes exact definitions of egocentric, intrinsic or retinal relative reference frames, and egocentric or allocentric cardinal relative reference frames. Invariants of descriptions with respect to classes of reference frames are discussed and some hints for the pragmatic preference of one or the other reference frame suggested. The paper demonstrates two alternative computational methods for Levelt's perspective taking, which deduces another person's egocentric perspective from the speaker's egocentric (perceptive) perspective. One method is assuming imagistic (analog) representations and the other method works with a propositional (qualitative) representation. Precise hypotheses can be formulated in the formalized framework to construct human subject tests to differentiate between these alternatives.