Responses to a smaller version of the image from page 578 by cells sensitive to all 16 possible 2×2 blocks, as well as their repetitive 3×3 extensions. Patches which appear to have different textures in the original image are seen to contain characteristically different densities of these various blocks. I strongly suspect that it is density differences such as these that allow our visual system to distinguish textures.
![](/nks/pages/p581--visual-perception/image-xlarge.png)
![](/nks/pages/p581--visual-perception/image-large.png)
![](/nks/pages/p581--visual-perception/image-medium.png)
![](/nks/pages/p581--visual-perception/image-small.png)