This turns out to be the case 
wherever in area 17 we record. 
In the fovea, the receptive 
fields are tiny, and so is the 
movement in the visual field 
produced by a 2-millimeter 
movement along the cortex: in 
the periphery, both the 
receptive fields and the 
movements are much larger, as 
illustrated in the figure to the 
left.

In a macaque monkey, the 
upper-layer receptive fields 
grow larger as eccentricity 
increases from the fovea (0 
degrees). Also growing by an 
equal amount is the distance 
the receptive fields move in the 
visual field when an electrode 
moves 2 millimeters along the 
cortex parallel to the surface.