M and P Pathways and the Perception of Figure and Ground

This chapter explains M and P pathways and the perception of figure and ground. It illustrates that M and P pathways can be identified with neural signals for ground and figure processing respectively. The appearance of the segmented visual image can be determined in part by the relative strength of activity in the two pathways. Relative activity in the two pathways may also determine apparent size, depth, brightness and flicker frequency of the regions. The chapter discusses the correlations between the spatial and temporal frequency composition of regions of ambiguous displays and the determination of which regions of the image appear predominantly as figure. In a search for a mechanism, the models are found that are restricted to spatial or temporal channels alone cannot explain all the data associated with this effect. A model which assumes antagonistic interactions between a set of temporal channels coding regions for ground and a set of spatial channels coding regions for figure appears to provide a fair explanation for the results.