backward masking

1 psychology :  masking (see ¹masking 2c) of one stimulus by the occurrence of another stimulus immediately after it In backward masking, the stimulus of interest is presented to the subject followed within milliseconds by another related stimulus that masks the effect of the first. — Nita A. Farahany, Stanford Law Review, February 2012 If researchers flash a word on a screen for a few milliseconds and immediately follow it by a pattern of random lines, the viewer cannot report the word (backward masking). — Rita L. Atkinson et al., Introduction to Psychology, 9th edition, 1987

2 :  backmasking The religious right accused the band of using backward masking to hide satanic messages … a charge that was dismissed by both the band and the general public. — Wayne Bledsoe, Knoxville (Tennessee) News-Sentinel, 3 Mar. 1995 “Free as a Bird,” the “new” Beatles recording unveiled at the end of Sunday's televised “Beatles Anthology,” ends with a bit of backward masking. It sounds like gibberish until it's played backward to reveal John Lennon saying, “It turned out nice again.” — Richard Harrington, Washington Post, 22 Nov. 1995