(A) Spike responses in an On parasol ganglion cell to receding (left) and approaching (middle) annuli presented at a series of contrasts. Right, Average spike rate during movement of receding (red) and approaching (black) annuli as a function of stimulus contrast. (B–F) Same as (A) for Off parasol (B), On smooth monostratified (C), Off smooth monostratified (D), broad thorny (E), and large bistratified ganglion cells (F). (G) Approach sensitivity index values for the stimulus paradigm. Transparent shapes indicate individual cells. Opaque shapes and error bars indicate mean ± SEM. Asterisks indicate statistically significant values, determined using the Wilcoxon signed rank test.