Notice that the colour afterimage appears in your blind spot, filling in the space defined by the black border. What would happen if you changed the black border? We know from other research that filling in of afterimages is strongly affected by the shapes that are present for the colour to 'fill in' (van Lier, Vergeer and Anstis, 2009).
What we understand less well is just how complex this active filling in can get, and how it interacts with attention (and its opposite, the ignoring). One way of getting a feel for this ignoring is to put to good use the training you have given yourself in learning to look at a different place from the center of your vision (called 'covert attention' by psychologists). How good is the resolution for different things at different distances from the centre of your vision? Notice how you can't see colours as well in the periphery, but this is something, like the blind spot, that
