Abstract: Processing of the visual world around us critically depends upon analysis of spatial relations between objects in scenes and analysis of subcomponents within complex multi-part objects. Spatial relations between objects can be represented either categorically or coordinately. The research results of the separation of processing two kinds of spatial relations are unstable and limited to the level at which two types of processing can affect each other. The analysis was not conducted on whether the processing of spatial relations would implicitly include spatial relations to another. The inevitable interference and interaction with each other in the two tasks of relations existed in previous studies, and the difficulties in the two tasks are different. All of these factors, therefore, could influence the analysis of the relations between the two kinds of processing of spatial relations. Spatial relations are not only required by the visual analysis and the formation of a perceptual representation, but also, they form a conceptual representation due to the exchange. The understanding of spatial relations is the transformation of conceptual representation into the perceptual representation, while the expression of spatial relations is the transformation of perceptual representation into the conceptual representation. The reference system links the perceptual representation and the conceptual representation. The reference system is characterized as a three dimensional axial system, which is defined by a number of parameters, including origin, orientation, direction, spatial templates, and distance. Reference frame can be free to adjust each parameter, and move around the space as with any object, therefore, the reference frame is of a good flexibility. The processing of visuospatial relations is the expression of spatial relations, which is the transformation of perceptual representation into the conceptual representation. No studies by now, however, have explored the representation of reference frame and parameters in the processing of visuospatial relations.
In the three experiments, we collected response time, controlled across prime trials and probe trials in which orientation, direction, and distance between the objects matched or mismatched, and investigated the representation of reference frame parameters in a coordinate spatial relations processing.
The results showed that the representation of direction existed in the coordinate relations processing, and the parameters of orientation existed in the contexts of certain tasks. Facilitation, when prime/probe direction matched, derived from the representation of direction in a coordinate spatial relations processing, rather than the similarity of perception units. Facilitation, when prime/probe distance matched, only occurred when the relations of location of prime/probe was coaxial in a reference frame both in experiment I and experiment II.
The present results suggested that the representation of reference frame seems to be associated with the endpoint of reference frame in the coordinate relations processing, and in the contexts of certain tasks, be associated with axis of reference frame at a more general level. The processing of representation further indicated that in the paradigm of this research, a coordinate relations processing implicitly included categorical spatial relations, and in the contexts of certain tasks, spatial vertical / horizontal categorical spatial relations were included. Finally, the distance representation seems to be associated with a particular axis of reference frame, being applied across endpoints of the axes in the processing of coordinate relations.

Key words: categorical and coordinate spatial relations, perceptual representation, reference frames, distance, direction, orientation