Through “Neon color spreading” color is spread to where there is no color! See the following demonstration:
In (a), between the red bars, the white background can be seen, however in (b), adding the black flankers causes the spread of weak neon red within an illusory circle that connects the black bar ends. At first glance, it is hard to see; be patient for a while till you get the effect, after that it becomes easy to capture even weaker neon effects.
Grossberg and Mingolla in 1985 developed a neural model that could explain neon color spreading. One of the problems that now we are concerned with can be depicted as the following:
In (a) neon spread is visible, however in (b) the effect is blocked. Notably, the geometry of (a) and (b) are the same, therefore, just different coloring upon the same geometry let or block the neon effect. How can a laminar cortical model discriminate between these two situations?
We call the effect of different painting on neon color spreading or blockade “contrast relation constraint”. This constraint can be found in another phenomenon: Transparency
In (a), just the bottom square can be seen transparent over the top one, in (b) either of squares can be seen transparent over the other, and in (c), non of them. Figures (a), (b), and (c) have same geometry of edges; once again “contrast relation constraint” shows its effect on generating or blocking the transparency. How can a laminar cortical model discriminate between these situations? Is it possible to find a unified laminar circuit to explain both transparency and neon color spreading generation and blockade?
The following two animations give you a more dynamic sense of:
(A) Neon color spreading, where the neon haze follows the changing color of the middle cross
(Click on the above icon and make the player
screen size the same as the icon size)
B) Transparency, where its presence or absence follows the contrast relation change
(Click on the above icon empty corners and make
the player screen size the same as the icon size)
We have presented the results of the model in a few conferences as listed below:
Grossberg S., & Yazdanbakhsh A. (2003a). Laminar cortical dynamics of 3D surface stratification, transparency, and neon spreading.
3rd annual meeting of Vision Sciences Society, FR43, pp. 77
Grossberg S., & Yazdanbakhsh A. (2003b). Laminar Cortical Mechanisms of 3D Surface Processing.
Society for Neuroscience 33rd annual meeting, 339.5