ABSTRACT
In Chapter 1, I argued for a hierarchical organization of spatial coordinates that define object/spaces at several levels in perception (akin to Rock’s, 1990, proposal for a hierarchical organization of reference frames). But in order to think about how this object/space hierarchy could be useful for perception and attentional selection, we need to know what spatial properties would be critical in establishing a spatial reference frame. What are its components? What distinguishes one frame from another? Are there infinite numbers of frames or are there only a few? To address these questions, I will begin by appealing to analytic geometry. The x and y axes in Figure 2.1 are part of a very familiar structure and represent a space in which every point can be defined in x, y coordinates in a two-dimensional (2-D) space. A 3-D coordinate would add a z-axis and a third dimension, but for simplicity the 2-D coordinate will be used here. By frame of reference, I simply mean what others have already specified, namely, a set of reference standards that on a set of coordinates define an origin (where the axes intersect), axis orientation, and sense of direction, or a positive and negative value (see Palmer, 1999). Evidence for the neuropsychological importance of each of these factors will be explored in the sections that follow, but first it will be useful to examine how frames of reference have influenced the study of visual perceptual organization.
