Dear All: White on Black cannot be compared with  Black on White since the former may have unlimited contrast and the latter- the maximum contrast only one. Stars on a dark sky are visible even though subtend a fraction of 1 arc-min. The  earliest reference was to Hartridge in 1930ies. If, however, we detect a spot on a gray background, white [or strictly lighter] spots are equally detectable as black [strictly darker] spots on the same grey background.
Surprisingly, their detection contrast thresholds l[light vs dark spots or lines]   are not only equal but sub-served by the most sensitive spatial frequency channel [around 3 - 5 cycles/deg, not 30 cycles/deg]. in other word 'hyper-acuity is a myth.
 I mentioned these problems in many articles the earliest Kulikowski 1967 - Avtometria; Kulikowski &King-Smith 1873 and my book chapters. I'll be happy to explained the details. Greetings. Janus