In 1975, S. Potter noted in "Changing English" that, "nearly half a century ago Edward Sapir predicted the demise of "whom", showing at great length that it was doomed because it was 'psychologically isolated' from the objective pronouns me, us, him, her, them on the one hand, and the invariables which, what, that and where, when, how, why on the other." By 1978, the 'who'–'whom' distinction was identified as having "slipped so badly that is almost totally uninformative". According to the OED (2nd edition, 1989), "whom" is "no longer current in natural colloquial speech". Lasnik and Sobin argue that surviving occurrences of "whom" are not part of ordinary English grammar, but the result of extra-grammatical rules for producing "prestige" forms.