Chapter 2 SENSORIMOTOR TRANSFORMATION It is a truism "to say that any description of a given state of matter is frame dependent" (Paillard, 1991a, p. 471). Such spatial frameworks are fundamental to our perceptual and motor experiences. Different spatial frameworks underlie perception and motor mechanics, and perceptual-motor integration can be thought of as transformation among reference frames (Simpson & Graf, 1985). In this chapter we first examine the various kinds of reference frames that can be identified for the perceptual-motor system. Then we consider how information in particular frames of reference may be represented (coordinate systems or maps) to define structured spaces. Finally, we discuss the nature of the rules governing transformations among the various perceptual-motor spaces and note some suggested transformational mechanisms.