 Chubb and his colleagues researched this illusion by showing various combinations of foreground objects and background fields to human test subjects and asking them to rate the sharpness of the visual contrast in each foreground object.They found that subjects viewing a patch of random visual texture embedded in a surrounding background field were likely to report different perceptions of visual contrast for the central target patch depending on the relative contrast of the background field.Furthermore, the apparent brightness/ dullness of a texture patch varied as the background varied.