Scotopic foveal afterimages
David H Hubei, Piers DL Howe, Amanda M Duffy, Adriana Hernandez
Perception | SAGE PUBLICATIONS LTD | Published : 2009
If, after being in the dark for many minutes, one views an extended surface under dim (scotopic) illumination, one fails to see any hint of the dark spot at the center of gaze that might be expected from the absence of rods in the fovea. Here we report that, if the surface is suddenly completely darkened, one sees for a few seconds a relatively bright spot, about 2 deg in size, at the point of fixation. If the surface is now restored to its original brightness, a dark spot of similar size appears where one fixates, that again lasts for several seconds. All this can be observed with no elaborate apparatus.
Awarded by NIH
Awarded by ARO
The research was supported by NIH grant EY00605 to DHH, a postdoctoral fellowship from the Helen Hay Whitney foundation to PDLH, and by ARO grant 46961 to Margaret Livingstone. We are indebted to Imme S Kaschner for help in translation of Exner's article, and to John Mollon and Nicholas Wade for useful comments in reviewing the paper.