Figure 5. Comparing stimulus parameters and performance.

After training and coherence testing were successfully completed, a separate testing day was used to examine mouse performance with changes in either dot diameter (a, b) or speed (step size) (c, d). Both dot diameter and speed were tested under a constant coherence of 48% to avoid a ceiling effect. (a) Individual mouse performance as dot size was varied. (b) The mean (black) and S.E.M. (gray) of the 4 mice from (a). (c) Individual mouse performance as the speed (resulting in changes in the step size) was varied. (d) The mean (black) and S.E.M. (gray) of the 4 mice from (c). The arrows in a-d indicate the values used for training. (e) Apparent size and speed of a dot (in degrees of visual field) changes as a function of viewing distance along the normal to the screen and along the perpendicular direction. As the animal approaches the screen along the midline, the relative dot size and speed increases for the dots closest to the midline (blue), and increases until a maximum is reached before decreasing again for the dots further from the midline (red, yellow). Viewing angles for the three screen location for a 76 mm viewing distance (along the central axis of the chamber) are indicated. (f) Panels (b) and (d) have been plotted with the x-axis converted to mm and mm/s assuming a viewing distance of 76 mm and angle of 28.1°.