A simple test of the "anchoring account" of simultaneous contrast

An "anchoring account" of the classic simultaneous contrast demonstration, first elucidated by Gilchrist et al. (1999) and most recently endorsed by Gilchrist (2014), is tested by adding a small white square to the black half of the display and a small black square to the white half of the display. The alteration should eliminate the effect, which, however, appears unaffected.