Object localization

Information about location is so ingrained in our understanding of visual processing that we sometimes take it for granted. From photoreceptor mosaics to evenly spaced retinal ganglion cell receptive fields to retinotopic maps in the brain, orderly representations of space are everywhere. This chapter asks us to consider the representation of visual space more closely, in particular its precision. How far apart do two points in space need to be before they can be recognized as distinct? What about judging the alignment between edges, the orientation of a line, or the distance between two lines? Are the limits of object localization in perception simply a result of the density of retinal neurons? If so, is photoreceptor density the limiting factor, or is the representation of space degraded in the retinal output by ganglion cells that integrate over hundreds or thousands of photoreceptors? These are some of the questions I will address. Hopefully, the reader will be as surprised and as fascinated by the answers as I was when I learned about this field.