In a series of studies, Schooler and Engstler-Schooler
(1990) showed that verbalization of previously
encountered non-verbal stimuli can impair subsequent memory performance. The present study investigates the possibility that the verbal disruption of non-verbal
processes, called verbal overshadowing, m a y be
applied to implicit learning, i.e., where what is
learned is difTicult to verbalize. One frequently
studied area of implicit learning is artificial grammars
(e.g., Reber & Lewis, 1977). In the artificial
grammar research, it has been shown that subjects can
learn information about regularities in letter strings
generated from a fmite state grammar, as measured by
transfer tests, while being unable to usefully state
what those regularities are. The apparent disparity
between subjects' competent performance on artificial
grammar tasks and their inabiUty to explain the rules
of those tasks suggests the possibility that
verbalization following memorization of artificial
grammar strings may impair subjects' performance on
a transfer task. In this study, subjects memorized a
subset of grammatical letter strings, then half of them
verbalized the rules they learned during memorization.
The verbal subjects performed significantly worse
than the non-verbal subjects on a transfer task,
providing preliminary evidence that verbalization may
impair transfer when the learned information is
difficult to verbalize