Purpose
This simulation allows you to view one of the more intriguing visual illusions, the scintillating grid illusion. As with the Hermann grid, the image that produces the illusion is quite simple. In fact, it is identical to the Hermann grid, except that the black squares are separated by gray (instead of white) lines, and there is a white circle filling each intersection. However, as you will see, these seemingly subtle differences dramatically change the illusion in a number of ways.
As with the Hermann grid, the simplicity of the illusion-inducing figure is misleading. This illusion is still employed today, sometimes in modified form, by scientists attempting to develop an understanding of how the essentially on-off response of rods and cones to photons of light gets translated into conscious perception of visual images. In the bigger picture, understanding the visual system helps us understand many other sensory modalities as well.

What Does The Scintillating Grid Simulation Allow You To Do?
This simulation allows you to work with the basic scintillating grid simulation, first in its normal form (black squares with gray gridlines), then provides you with the opportunity to vary a number of parameters and observed the effect on the illusion. The size of the squares and the width of the grid lines can be varied independently, as can the color of the squares and the grid lines. Finally, you have the option of working with two modified versions of the basic scintillating grid illusion, both based on the Hermann grid simulation. Since no published studies have employed these modified grids in studies of the scintillating grid illusion, you will be treading on new ground when you do those experiments!

What Does The Scintillating Grid Simulation Display?
When you initiate a simulation run, you will see a grid consisting of black squares separated by gray grid lines. A small white circle occupies each intersection. IF you can drag your eyes from the fascinating display, below the grid you will see two slider/textfield combinations that let you control the size of the grid squares and the width of the grid lines that separate them. As with other simulations you've already performed, you may change the value of these two parameters either by moving the slider or by typing the desired value in the textfield. On the right side of the display, top to bottom, you will see (i) checkboxes that let you change the color of the squares and the grid lines independently of each other, (ii) checkboxes that let you simulate alternate versions of the basic grid, and (iii) the usual control buttons.