Repetition Priming 461Neely and Kahan’s hypothesis is correct, then prime-task ef-
fects are not so problematic for the models of priming.
Global Context Effects
Recent experiments indicate that the global context estab-
lished by discourse or by the types of semantic relations
appearing in a test list can affect semantic priming. For exam-
ple, McKoon and Ratcliff (1995) placed a small number of
prime-target pairs related in a particular way (e.g., opposites,
close-far) in a list in which over half of all prime-target pairs
were related in a different manner (e.g., synonyms,mountain-
hill). Semantic priming in lexical decision and in naming was
virtually eliminated for the mismatching items. Hess, Foss, and
Carroll (1995) obtained similar results by varying the global
context established by short vignettes preceding target words.
Although one might be tempted to conclude from these
findings that all contextual facilitation is determined by
global context (e.g., Hess et al., 1995), this conclusion is not
justified. There is just too much evidence that semantic prim-
ing occurs between strongly related words in the most infe-
licitous of conditions (e.g., Fischler, 1977a; Neely, 1977). We
suspect that appropriate follow-up studies will show effects
of local context in addition to global context. The contribu-
tion of these studies is to demonstrate that semantic priming
is modulated by relations external to the word pairs. These
global context effects are a serious challenge to all existing
models of semantic priming.
Summary
Given that we used Neely’s (1991) review as a starting point,
it is appropriate to ask what has been learned about semantic
priming since the publication of that chapter.
First, a new class of models of priming, namely, distributed
network models, has been developed. One member of this
class of models, the learning models, can explain what may
turn out to be the most important new finding on semantic
priming, namely, semantic priming over very long lags.
Second, a great deal more has been learned about several
important priming phenomena: (a) There is probably a better
understanding of the conditions that contribute to automatic
versus strategic priming. (b) It is now clear that pure semantic
priming occurs, and there is evidence that it is produced by
automatic processes. (c) Mediated priming has now been
replicated by several investigators using a variety of tasks and
procedures. (d) Priming across lags of unrelated intervening
items has been replicated in several studies. Moreover, there is
new evidence that semantic priming can occur over very long
lags. (e) Several new investigations of backward priming have
appeared, and the results suggest that backward priming for
compounds (e.g.,hop-bell) is produced by strategic processes,
whereas backward priming between asymmetrically associ-
ated semantically related words (e.g.,light-lamp) is caused by
semantic overlap. (f ) An entirely new line of research on
subliminal priming has appeared, and it seems to converge
on the conclusion that semantic priming does not occur un-
consciously. (g) There is a better understanding of the role of
attention in semantic priming. Finally, (h) a new line of re-
search indicates that semantic priming is affected by the
global context in which prime-target pairs appear.
Third, although none of the models can account for all of
the major priming results, there are reasons to be optimistic
about future model development. Assuming, for the moment,
that long-term semantic priming turns out to be a robust phe-
nomenon, then distributed-network learning models offer an
appealing foundation for model development. If these mod-
els can be augmented with associative priming mechanisms
and appropriate attentional processes, they will go a long way
toward explaining the major findings in the literature.REPETITION PRIMINGWhereas semantic priming refers to a facilitation in perfor-
mance betweendifferentitems on the basis of shared meaning
or association, repetition priming refers to facilitated perfor-
mance based on a previous encounter with thesamestimulus.
Essentially, repetition priming reflects the degree to which a
single exposure to a stimulus during a study session leads to
faster or more accurate processing of that stimulus at a later
test (Tulving & Schacter, 1990).
Research on repetition priming has developed largely
from studies involving patients with anterograde amnesia.
This neurological disorder (or collection of disorders) is
characterized by a severely impaired ability to form new ex-
plicit memories (for review, see Squire, 1987). This type of
amnesia typically accompanies damage to the medial tempo-
ral lobes (e.g., for review, see Squire, 1992) or to the dien-
cephalic midline structures (as in Korsakoff’s syndrome; for
review, see Oscar-Berman, 1984; Shimamura, 1989). Am-
nesic patients show an impairment of the ability to explicitly
recall events that occur after the onset of their amnesia, de-
spite intact intellectual, language, and social skills. In spite of
showing severely degraded performance on tests of explicit
memory, which require conscious recollection, such as free
recall, cued recall, recognition, and paired-associate learning
(see also the chapter in this volume by Roediger & Marsh),