If you have already seen the Mach Band demonstration and followed its explanation you will recognize that a similar argument can be made to explain the appearance of the bright diagonal areas in this diagram. The receptive field section of this book reviews the physiological principles associated with this phenomenon.If you look closely at each receptive field overlaid on the figure you will note that a greater portion of the inhibitory surround is on a darker portion of the figure. The excitatory center, being so much smaller covers only a small section.
I have provided expanded view if the above is not yet quite clear to you.
Table of Contents
Subject Index
Table of Contents [When not using framtes]