Dynamic Luminance Effect
Look at the center of the following figure and move your head closer and further from the figure repeatedly. Does the “white spot” toward the center of the image appear to get larger and smaller?
The effect seen above has also been called the “here comes the sun ” effect and is caused by a change in the apparent brightness. More information about the Dynamic Luminance Effect can be found on PerceptualStuff.org run by D. Alan Stubbs.