Figure 1.
A top and side view of the optokinetic testing apparatus. The animal is enclosed in a central chamber which is suspended within a larger rotating drum. The drum contains high contrast stripes of varying widths (see Table 1) that when viewed from the calculated central distance correspond to a particular spatial frequency. Throughout testing different widths of stripes are used to determine visual acuity. The gray in the bottom panel represents a cut away portion of the outer drum so that the inner chamber can be seen. The opossum is not to scale.