Bruce, M. & Foster, J. J. (1982). The visibility of colored characters on colored backgrounds in viewdata displays. Visible Language, 16(4), 382-390.

An experiment is reported in which subjects were required to identify letters and digits presented on a viewdata display, and identification times were recorded. All 42 possible color-on-color combinations were shown as separate displays. The results indicate which color-on-color pairings significantly reduce character visibility, and a list of recommended combinations is given.