Journal of Experimental Social Psychology 36, 194–206 (2000)
doi:10.1006/jesp.1999.1415, available online at http://www.idealibrary.com on
Sources of Mental Contamination: Comparing the Effects of
Self-Generated versus Externally Provided Primes
Thomas Mussweiler and Roland Neumann
Universität Würzburg, Würzburg, Germany
Received February 18, 1999; revised October 12, 1999; accepted October 12, 1999
Social cognition research has closely examined the processes that are involved in the
correction for contaminating influences on judgment. Little is known, however, about how
a contaminating influence is detected in the first place. To remedy this shortcoming, we
propose a source-monitoring perspective on the detection of bias. This framework suggests
that contamination is more likely to occur if its source is similar to the target source.
Because judgment processes often involve elaborate internal processing of information,
knowledge that is internally generated rather than externally provided is less likely to be
seen as contaminating. As a consequence, judgments are more likely to be consistent with
the implications of internally generated than externally provided knowledge. The results of
two studies using different self-generation procedures (i.e., generating antonyms and
solving anagrams) are consistent with this prediction. They demonstrate that in a blatant
priming paradigm, judges only correct for the influence of externally provided primes
(which yields contrast) but not self-generated primes (which yields assimilation). The
implications of these findings are discussed in light of the literature on knowledgeaccessibility effects, source monitoring, and judgmental correction. r 2000 Academic Press
Key Words: self-generation; priming; source monitoring; correction.
Most judgments are too complex to allow for an exhaustive search of relevant
information. Consequently, judges often rely primarily on information that comes
to mind easily while making the judgment. Such accessible knowledge is
typically used as a judgmental basis, so that the critical judgment is assimilated
toward its implications. In order to be used as a judgmental basis, however, easily
accessible information has to be seen as relevant for the critical judgment (see
The present research was facilitated by a research grant from the Deutsche Forschungsgemeinschaft. We thank Galen V. Bodenhausen, Fritz Strack, and R. S. Wyer, Jr., for elaborate discussions of
the issue. Thanks also go to Iris Müller for her help in preparing the stimulus material and to Simon
Finkeldei, Cornelia Florig, and Daniela Meiser for their help in collecting the data.
Address correspondence and reprint requests to Thomas Mussweiler, Psychologie II, Universität
Würzburg, Röntgenring 10, 97070 Würzburg, Germany. E-mail: mussweiler@psychologie.uniwuerzburg.de.
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0022-1031/00 $35.00
Copyright r 2000 by Academic Press
All rights of reproduction in any form reserved.
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Higgins, 1996; Strack, 1992). If this is not the case, judges may forgo the use of
accessible knowledge and try to correct for its potentially contaminating influence
(Wilson & Brekke, 1994). The typical consequence of such a correction is that the
judgment is contrasted away from the implications of accessible knowledge
(Martin & Achee, 1992; Schwarz & Bless, 1992; Strack, 1992). Thus, whether
judgments are assimilated toward or contrasted away from the implications of
accessible knowledge critically depends on what is seen as the cause of accessibility. Before participants can use accessible knowledge to generate a specific
judgment, they have to identify the source of accessibility and determine whether
it is best attributed to the judgmental target itself or to a potentially contaminating
factor.
Given that the accessibility of a given construct can be increased by a multitude
of situational (e.g., priming; Higgins, Rholes, & Jones, 1977; Srull & Wyer, 1979)
and personal factors (e.g., chronic accessibility; Bargh, Bond, Lombardi, & Tota,
1986) this task of source identification is, in fact, difficult to master. Clearly,
correctly identifying the source of accessibility is a crucial prerequisite for
accurate judgment. In fact, it has been suggested that many instances of judgmental contamination (e.g., halo effects, mood-as-information effects) can be traced
back to source confusion (Wilson & Brekke, 1994). How, then, do people
differentiate between different sources of accessibility? How do they determine
whether the accessibility of information can be attributed to the judgmental target
or to a contaminating factor? Or, more generally speaking, how do they detect a
potential contamination or bias? To answer these questions, it may be useful to
apply insights into the general mechanisms that underlie the identification of the
sources of cognitive outcomes (e.g., Johnson, Hashtroudi, & Lindsay, 1993;
Johnson & Raye, 1981) to the realm of knowledge accessibility and judgmental
contamination.
SOURCE MONITORING AND THE DETECTION OF BIAS
The cognitive literature on source monitoring (for an overview, see Johnson et
al., 1993) has identified a number of factors that promote and hinder the accurate
identification of the source of a given memory. According to Johnson and
colleagues (e.g., Johnson et al., 1993; Johnson & Raye, 1981), source-monitoring
judgments are based on those characteristics that are typically associated with a
memory stemming from a particular source. For example, a person who is trying
to identify whether a particular memory is based on external input (e.g., a
perceptual experience) or internal generation (e.g., thought and imagination) may
search for those characteristics that are typically associated with these two types
of memories. Because memories originating in external input typically include
more perceptual and contextual information than internally generated memories,
a specific memory is likely to stem from external input if it includes a lot of these
details. Internally generated memories, on the other hand, typically include more
information about the kinds of mental operations that produced them. Thus, a
specific memory that includes a great deal of information about such operations is
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likely to be seen as internally generated. From this perspective, the accuracy of a
source-monitoring judgment critically depends on the amount of overlap between
the characteristics of the critical sources. The more two sources produce memorial
consequences that are clearly distinguishable, the easier it is to attribute a given
memory to one of them. The more similar these consequences are, however, the
more difficult source identification becomes and the more likely source confusion
errors are to occur.
What are the implications of this framework for the realm of knowledge
accessibility and judgment contamination? How do the principles that appear to
guide the identification of the source of a memory relate to the identification of the
source of accessibility? The source-monitoring perspective suggests that in order
to determine whether a particular concept came to mind because of the judgmental target itself or because of an extraneous factor, judges search for characteristics
that are typically associated with both sources. For example, judges who recall
that the word ‘‘adventurous’’ was part of a scrambled sentence (Srull & Wyer,
1979) which they unscrambled right before reading about an ambiguously
described target person (‘‘Donald’’) are likely to attribute accessibility to a
contaminating factor and may try to correct for its potential influence (Strack,
Schwarz, Bless, Kübler, & Wänke, 1993). Judges who recall how they extracted
the notion that Donald is adventurous from the target description, on the other
hand, are likely to attribute the accessibility of this concept to the judgmental
target itself and may readily use it to characterize Donald. To the extent that both
sources are clearly distinguishable, source identification is likely to be easy and
accurate. The more accessibility stemming from a contaminating source and the
target source (i.e., the judgmental target) are characterized by similar properties,
however, the more difficult and error prone the source identification process
becomes and the more likely source confusion is to occur. This suggests that
judges should be more likely to see accessible knowledge as contaminating and
try to correct for its influence if the source of accessibility is clearly distinguishable from the judgmental target.
The priming literature (for a recent review, see Higgins, 1996) is well
consistent with this assumption. It has repeatedly been demonstrated that judgments are more likely to be contrasted away from the implications of accessible
knowledge if the source of accessibility is clearly distinguishable from the
judgmental target. For example, awareness of the priming event (e.g., Lombardi,
Higgins, & Bargh, 1987; Strack et al., 1993) critically determines whether
assimilation or contrast occurs. If participants are unaware of the priming event
(i.e., the source of accessibility is indistinguishable from the judgmental target),
judgments are typically assimilated to the primes. Thus, if a subtle priming
procedure is used (Higgins et al., 1977; Srull & Wyer, 1979, 1980), participants
are unlikely to be aware of the fact that a specific trait category comes to mind
because it has been activated in the preceding priming task (i.e., that accessibility
stems from a contaminating source). As a consequence, judgments will be based
on the implications of accessible knowledge which leads to assimilation. If,
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however, judges are aware of the priming episode and can thus distinguish the
source of accessibility from the judgmental target, contrast is more likely to occur
(Strack et al., 1993). Thus, blatant priming (Martin, 1986; Martin et al., 1990)
typically induces participants to contrast their judgments away from the implications of the primed concept. This may be the case because with blatant priming,
the source of accessibility is easier to distinguish from the judgmental target so
that judges may deliberately try to correct for its potentially contaminating
influence.
INTERNAL VERSUS EXTERNAL SOURCES OF ACCESSIBILITY
One factor that is likely to influence the degree to which a contaminating source
of accessibility is distinguishable from the target source is whether the contaminating source is external or internal in nature. As we have pointed out before, the
source-monitoring framework (Johnson et al., 1993; Johnson & Raye, 1981)
suggests that the less overlap in characteristics two sources have, the easier they
are to distinguish and the less likely source confusion is to occur. In many
judgment situations, however, external sources of accessibility share less properties with the target source than internal sources and should thus be easier to
distinguish.
To see this, it is important to specify the properties that characterize the target
source in social judgment in general and judgmental priming paradigms in
particular. One crucial characteristic here is that accessibility stemming from the
judgmental target itself is likely to be the result of an internal generation process.
Because explicit characterizations (e.g., ‘‘Donald is adventurous’’) are typically
not provided, participants have to relate the information that is provided about the
target person to their stored knowledge about similar behaviors. That is, they have
to engage in elaborate mental operations in order to judge the target person. Given
the general properties of external and internal sources (Johnson et al., 1993),
accessibility stemming from the target source is thus likely to be characterized by
a lot of detail about mental operations and very little perceptual and contextual
detail. In this respect, it contrasts well with accessibility stemming from an
external contaminating source, which is likely to be characterized by a lot of
perceptual and contextual detail and little detail about mental operations. For
example, in the standard priming paradigm, participants may still remember the
context in which a prime was presented (e.g., the scrambled sentence; Srull &
Wyer, 1979) or the font in which it was printed. Because such details are unlikely
to result from the internal generation process that is responsible for increased
levels of accessibility stemming from the target source, they help to distinguish
accessibility stemming from an external contaminating source from that produced
by the target source. Internal contaminating sources, however, do not produce
such differentiating perceptual and contextual detail. Rather, they are likely to be
characterized by the same kind of details about mental operations as the target
source. In tandem, this lack of distinguishing properties (i.e., perceptual and
contextual detail) and presence of shared properties (i.e., detail about mental
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operations) renders source identification more difficult. As a consequence, judges
are more likely to attribute the accessibility stemming from an internal contaminating source to the judgmental target.
Consistent with this contention, recent research examining the role of source
monitoring in cryptomnesia (i.e., false beliefs in the originality of one’s ideas;
Landau & Marsh, 1997) has demonstrated that source confusion is more likely to
occur, if the two critical sources both involve internal generation processes. In one
study (Landau & Marsh, 1997) participants had to list solutions to a word-search
puzzle in competition with a computer. After an initial generation phase in which
both the participants and the computer listed as many solutions as they could find,
participants were instructed to list all the solutions that they themselves had come
up with. In this paradigm, giving a solution that was provided by the computer
constitutes an instance of source confusion. Thus, in order to provide a correct
answer, participants have to distinguish between their own responses and those of
the computer. For some of the participants, distinguishing between the external
contaminating source (i.e., the computer) and the internal target source (i.e., the
self) was complicated by requiring them to anticipate what solution the computer
would come up with. Doing so adds an aspect of self-generation to the computergenerated solutions and thus renders them more similar to the self-generated
solutions. As a consequence, participants who anticipated the computer-generated
solutions should show more signs of source confusion. In fact, this is exactly what
Landau and Marsh (1997) found: Anticipating the computer-generated solutions
induced participants to mistake more of these solutions as their own. These
findings indicate that it may be more difficult to distinguish the cognitive
consequences of a contaminating source from those of the target source, if both
include self-generation processes.
Applied to the realm of knowledge-accessibility effects, these findings suggest
that accessibility stemming from an internal contaminating source may be more
likely to be attributed to the target source than accessibility stemming from an
external source. Recent research on knowledge-accessibility effects outside of the
standard priming paradigm provides initial support for this assumption. In
particular, it has been demonstrated (Mussweiler & Strack, 1999) that the
self-generation of judgment-relevant knowledge contributes to the assimilative
effects of judgmental anchoring (Tversky & Kahneman, 1974)—the assimilation
of a numeric estimate to a previously considered standard.
PRESENT RESEARCH
Consistent with our theoretical argument, these findings suggest that an internal
contaminating source may be more difficult to distinguish from a primarily
internal target source than an external contaminating source. For the realm of
knowledge-accessibility effects and judgment contamination, this suggests that
judges may be less likely to correct for the potentially contaminating effects of
internally generated knowledge. The present research was designed to test this
possibility. To do so, we used a blatant priming paradigm (Martin, 1986; Martin et
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al., 1990). For about half of our participants, the prime words were externally
provided. Consistent with the standard finding in the blatant priming paradigm,
we expected that these participants would contrast their judgments about the
target person away from the implications of the primes. This should be the case
because accessibility resulting from the external contaminating source should be
easy to distinguish from accessibility resulting from the target source, so that
participants correct for its assumed influence. The other half of our participants,
however, generated the primes themselves. For them, accessibility stemming
from the contaminating source and the target source should be more difficult to
distinguish. As a consequence, judges are more likely to use knowledge that was
rendered accessible by the contaminating source as a basis for their judgment (i.e.,
they are less likely to correct) so that judgments should be assimilated to the
primes. In summary, externally provided blatant primes should yield contrast,
whereas self-generated primes should yield assimilation.
STUDY 1
In Study 1, participants were blatantly primed with words related to the trait
concept of unlikeability or words that are neutral with respect to the likeability
dimension. Using a yoked design, half of the participants generated these words
themselves by finding antonyms to a list of words associated with likeability,
while the other half received words generated by one of the other participants.
Subsequently, participants were told to judge the likeability of an ambiguously
described target person. To underline that the primed trait words are not relevant
for judgments of the target person, both tasks were said to be completely
unrelated.
Method
Participants. Thirty-three nonpsychology students at the University of Würzburg were recruited as participants and randomly assigned to one of four
experimental conditions. They participated in groups of up to 10 and were offered
a chocolate bar as compensation.
Materials. During our priming procedure, participants received a list of 15
words under the guise of a pretest for a study on language comprehension. For
half of the participants, all 15 words were neutral with respect to the critical
likeability dimension (e.g., sleep, heavy). For the other half, 10 of the 15 words
were closely associated with likeability (e.g., love, to pet).
In the self-generation condition, participants were instructed to list three
antonyms for each of the words. It was explained that antonyms are words that are
opposite to each other in meaning, so that ‘‘healthy,’’ for example, is an antonym
for ‘‘sick.’’ Because the critical target words were closely associated with
likeability (e.g., to love), the generated antonyms are likely to be associated with
unlikeability, so that the latter trait concept should be primed by our manipulation.
Using a yoked design, each participant in the externally provided condition was
given the list of the target words and the respective antonyms that were listed by
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one of the participants in the self-generation condition. They were instructed to
indicate for each of the listed antonyms whether it constitutes a high- or
low-frequency word. In sum, the four experimental conditions resulted from an
orthogonal combination of the two factors generation (self-generated vs externally provided) and priming (unlikeable vs control).
We used a translation of Srull and Wyer’s (1979) ‘‘Donald’’ paragraph as our
target description. In this paragraph the target person (‘‘Marcus’’) was described
as performing a number of evaluatively ambiguous behaviors (e.g., denying a
salesman entry into the flat). Participants judged ‘‘Marcus’’ along 11 9-point
rating scales, ranging from ‘‘1’’ (e.g., unlikeable) to ‘‘9’’ (e.g., likeable), one of
which pertained to Marcus’ likeability.
Procedure. Participants were contacted in the university cafeteria and asked to
take part in two psychological experiments. They were guided to a separate room.
Upon arrival they were greeted by another experimenter, who handed them a
stack of four folders, instructed them to work through these folders in the given
order, and to close each of them after completion of the included material.
The first folder included general instructions. Here, participants were informed
that they were about to take part in two separate studies, one on language
comprehension and one on impression formation. It was pointed out that both
studies were completely unrelated and were administered together solely for
efficiency reasons. To further underline the unrelatedness of both studies, the
materials pertaining to each of them were printed in different fonts and on paper
with different shades of white.
The second folder included the study on ‘‘language comprehension,’’ which
contained the priming manipulation. The third folder contained the instructions
and the target description for the impression-formation task. Here, participants
were first informed that we were interested in how children judge people. To
investigate this question, we would first have to find some appropriate target
descriptions. Therefore, we would like them to carefully read the following
description of a person named ‘‘Marcus’’ and would then asked them to judge this
person on a number of personality dimensions. The fourth folder included the
central dependent measure, which assessed participants’ judgments about Marcus.
After completion of these four folders, participants were debriefed, thanked for
their participation, and offered a chocolate bar as compensation.
Results
Preliminary analysis. To test for the effectiveness of our priming manipulation,
we had two independent judges rate how strongly the generated antonyms are
associated with likeability. They rated each of the listed antonyms along a 5-point
scale ranging from 22 (‘‘extremely unlikeable’’) to 2 (‘‘extremely likeable’’).
The individual scores for each of the antonyms were combined into one overall
score for each participant. Both judges showed high agreement (r 5 .99), so that
their ratings were combined. As expected, the antonyms generated in the unlikeability priming condition proved to be more strongly associated with unlikeability
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TABLE 1
Mean Ratings of ‘‘Marcus’ ’’ Likeability by Generation and Priming
Generation
Priming
Externally provided
Self-generated
Neutral
Unlikeable
2.00
3.38
2.38
1.13
Note. Values depict mean ratings on a 9-point rating scale ranging from 1 (‘‘unlikeable’’) to 9
(‘‘likeable’’). The higher the value the higher the judged likeability; N 5 8 for all cells.
(M 5 21.21) than those generated in the control condition (M 5 .15), t(14) 5
23.41, p , .001. Thus, our priming manipulation induced participants to generate words associated with unlikeability.
Target ratings. Inspection of Table 1 reveals that the judged likeability of the
target person ‘‘Marcus’’ depended on the priming and generation conditions.1
Specifically, participants who received externally provided antonyms judged
Marcus to be more likeable in the priming condition than in the control condition.
Thus, participants in the externally provided condition contrasted their judgments
away from the implications of the prime. For participants who generated primes
themselves, however, assimilation resulted: They judged Marcus as less likeable
in the priming condition than in the control condition. This pattern produced a
significant interaction effect in a 2 (self-generated vs externally provided) 3 2
(priming vs control) ANOVA using the likeability ratings as the dependent
measure, F(1, 28) 5 4.46, p , .05.
An analysis of the individual contrasts further revealed that the difference
between the priming and the control condition was marginally significant in both
the self-generated condition, t(28) 5 1.75, p , .06 (one-tailed), and the externally
provided condition, t(28) 5 1.35, p , .1 (one-tailed).
Discussion
These findings provide initial support for our predictions. They demonstrate
that the direction of the priming influence may depend on whether primes are
externally provided or self-generated. As in previous research that used blatant
priming (e.g., Martin, 1986; Martin et al., 1990) judgments were contrasted away
from the implications of externally provided primes. For self-generated primes,
however, this tendency was reversed. Here judgments were assimilated to the
implications of the primes. Although this pattern proved to be reliable in the
overall ANOVA, the individual contrasts for the assimilation and the contrast
effect were not quite significant. Given the small sample size, this is likely to be
primarily a problem of statistical power. To remedy this weakness, we used a
larger sample in our second experiment.
1
No reliable effects were obtained on the neutral dimensions, all F’s , 1.8, p . .18.
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A second concern Study 2 was designed to address pertains to a potential
ambiguity associated with the self-generation procedure used in Study 1. One
may argue that the obtained reversal in the direction of the priming effect may be
caused by a specific feature of our procedure rather than the mode of generation of
the primes. In particular, participants who generate antonyms (e.g., hate) to the
provided target words (e.g., love) may focus on these target words more than
participants who simply rated the antonyms generated by another participant.
Consequently, the two opposing concepts of ‘‘likeability’’ and ‘‘unlikeability’’
may be primed simultaneously for participants in the self-generated condition:
Focusing on the ‘‘likeable’’ target words may prime ‘‘likeability,’’ whereas
generating antonyms may prime ‘‘unlikeability.’’ Thus, it is not clear whether the
effects we obtained in the self-generation condition represent contrast away from
‘‘likeability’’ or assimilation toward ‘‘unlikeability,’’ as we have assumed. To
clarify this ambiguity and provide more unequivocal support for our assumption
that self-generated primes produce assimilation, Study 2 used a different selfgeneration procedure.
STUDY 2
Specifically, we had participants in the self-generation condition solve a set of
15 anagrams. The solutions to these anagrams were either closely associated with
likeability (e.g., love) or not associated with likeability at all (e.g., sleep).
Participants in the externally provided condition were provided with the anagrams
as well as with their solutions and were instructed to rate how difficult the
respective anagrams were. Note that unlike the antonym-generation procedure
used in Study 1, this anagram procedure exposes all participants only to the
concept of likeability and not to its opposite. Thus, only one concept is primed in
both the self-generated and the externally provided conditions. To the extent that
the results of Study 1 are not an artifact of the antonym-generation procedure,
solving anagrams should produce an assimilation effect, whereas rating their
difficulty should yield contrast.
Method
Participants. Eighty nonpsychology students at the University of Würzburg
were recruited as participants and randomly assigned to one of four experimental
conditions. They participated in groups of up to four and received 16 German
Marks (about $9 U.S. at the time) as a compensation.
Materials and procedure. Upon arrival in the lab, participants were directed to
a separate booth and received a stack of folders similar to the one described in
Study 1. The main difference between both studies pertains to the nature of the
priming manipulation. Under the guise of a pretest for a study on language
comprehension, participants received a list of 15 anagrams. For half of the
participants, the solutions to these anagrams were the 15 neutral words used in
Study 1. For the other half, they were the 10 words associated with likeability as
well as the 5 neutral words used before. In the self-generation condition,
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TABLE 2
Mean Ratings of ‘‘Marcus’’’ Likeability by Generation and Priming
Generation
Priming
Externally provided
Self-generated
Neutral
Likeable
2.55
1.98
2.13
3.65
Note. Values represent mean ratings on a 9-point rating scale ranging from 1 (‘‘unlikeable’’/
‘‘unfriendly’’) to 9 (‘‘likeable’’/‘‘friendly’’). The higher the value the higher the judged likeability;
N 5 20 for all cells.
participants had to solve the anagrams themselves. We carefully pretested each
anagram to ensure that all participants would be able to solve them and that the
solutions are indeed identical to the words used in Study 1. Participants in the
externally provided condition received the same anagrams along with their
respective solutions. They were instructed to indicate whether they see each of the
anagrams as easy or difficult to solve. Note that because in contrast to Study 1 this
procedure does not expose participants to antonyms for the target words, it primes
‘‘likeability’’ rather than ‘‘unlikeability.’’ In sum, the four experimental conditions
resulted from an orthogonal combination of the two factors generation (selfgenerated vs externally provided) and priming (likeable vs control).
We used the same target description as in Study 1. After reading this
description, participants judged ‘‘Marcus’’ along 11 dimensions. To provide a
more sensitive measure as the one used in Study 1, we included two critical
dimensions which are both closely associated with likeability. Specifically,
participants rated how likeable (1 5 unlikeable, 9 5 likeable) and how friendly
(1 5 unfriendly, 9 5 friendly) ‘‘Marcus’’ was. After completion of these questions, participants were thanked, debriefed, and offered their compensation.
Results and Discussion
Ratings on the two critical dimension were closely related (r 5 .60, p , .001)
and thus combined into one likeability score.2 Inspection of Table 2 reveals the
same pattern obtained in Study 1. Specifically, participants who received externally provided primes judged Marcus to be less likeable in the priming condition
than in the control condition. Thus, they contrasted their evaluations of Marcus
away from the implications of the primes. Participants who generated the primes
themselves, however, assimilated their judgments about Marcus to the primes,
such that they judged Marcus as more likeable in the priming than in the control
condition. This pattern produced a significant interaction effect in a 2 (selfgenerated vs externally provided) 3 2 (priming vs control) ANOVA, using the
combined likeability score as a dependent measure, F(1, 76) 5 13.17, p , .001.
2
No reliable effects were obtained on the neutral dimensions, all F’s , 1.6, p . .2.
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An analysis of the individual contrasts further revealed that the difference
between the priming and the control condition was significant for self-generated
primes, t(76) 5 3.49, p , .001 (one-tailed) and marginally significant for
externally provided primes, t(76) 5 1.51, p , .07 (one-tailed). Inspection of the
means suggests that the latter contrast may not have obtained significance because
of a floor effect: Control participants already judged Marcus extremely negatively,
so that it was difficult for the experimental participants to give even lower ratings.
Despite this restriction, combining the effects of Studies 1 and 2 (Rosenthal &
Rosnow, 1991) reveals that across both studies the contrast effect that resulted
from exposure to externally provided primes was reliable, Z 5 1.93, p , .026
(one-tailed).3
Thus, using a self-generation procedure that rules out the alternative explanation outlined before, these findings replicate those of Study 1.
GENERAL DISCUSSION
In summary, the results of Studies 1 and 2 demonstrate that the direction of a
priming influence depends on whether the primes are externally provided or
self-generated. Consistent with many other findings (e.g., Martin, 1986; Martin et
al., 1990), we found that judgments about an ambiguously described target person
are contrasted away from the implications of externally provided primes. In light
of current conceptualizations (e.g., Higgins, 1996; Martin & Achee, 1992; Strack,
1992), which assume that such contrast effects are typically caused by judgmental
correction, this finding suggests that participants attempted to correct for the
influence of externally provided primes. For self-generated primes, however,
impressions of the target person were assimilated toward the primes. As pointed
out before, here assimilation may prevail because judges fail to correct for the
influence of self-generated primes. Specifically, accessibility stemming from an
internal contaminating source may be more difficult to distinguish from accessibility stemming from the target itself, so that judges may mistakenly use easily
accessible concepts to characterize the target person even if these concepts were
rendered accessible by the priming task. The fact that in Study 1 the target
evaluations in the self-generated priming condition were extremely negative
supports the assumption that self-generation prevented judgmental correction. In
particular, the mean judgment for this group (M 5 1.13) was virtually at the
negative end point of the provided scale. This suggests that participants did, in
fact, not correct their evaluations of the target. Thus, despite the blatantness of the
primes, self-generation produced what is typically considered to be the default
effect of knowledge accessibility, namely assimilation (cf., Higgins, 1996; Strack,
1992).
The current findings are well consistent with previous results demonstrating
3 To combine both analyses, we followed the procedure suggested by Rosenthal and Rosnow
(1991). First, we determined the standard normal deviates (Z) for the p values obtained in both studies.
These were Z 5 1.25 for Study 1 and Z 5 1.48 for Study 2. Based on these individual Zs, we calculated
a combined value of Z 5 1.93, which is significant at p , .026.
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SELF-GENERATION AND PRIMING
that self-generation contributes to assimilation in other knowledge-accessibility
paradigms such as judgmental anchoring (Mussweiler & Strack, 1999) and belief
perseverance (Davies, 1997). Taken together, these findings converge on the
conclusion that judges are less likely to correct for a potentially contaminating
effect of self-generated knowledge. From the current theoretical perspective, this
may be the case because accessibility stemming from an internal contaminating
source is more difficult to distinguish from accessibility that may rightfully be
attributed to the judgmental target. In this respect, self-generation thwarts accurate source monitoring and ultimately impedes attempts to correct for contaminating influences.
The present research examined self-generation as one factor that may blur the
distinction between accessibility resulting from a contaminating source and the
target source. The source-monitoring framework lined out by Johnson and
colleagues (e.g., Johnson et al., 1993; Johnson & Raye, 1981), however, suggests
many other factors that may have very similar effects. In fact, any factor that
renders the identification of the source of accessibility more difficult is likely to
produce more source confusion and may thus prevent correction for its influence.
For example, because source-monitoring judgments critically depend on how
well the respective sources are encoded, putting judges under cognitive load
during the priming task may thwart accurate source identification. As a consequence, judgments may be more consistent with the primed concept. Clearly, this
possibility—although plausible on theoretical grounds—remains to be tested
empirically.
CONCLUSION
For the past 2 decades, knowledge-accessibility effects have been one of the
main foci of social cognition research. Although, elaborate models specifying the
judgmental mechanisms that underlie the correction for contaminating influences
on knowledge accessibility have been proposed (e.g., Martin & Achee, 1992;
Strack, 1992; Wegener & Petty, 1997; Wilson & Brekke, 1994), little is known
about how judges detect contamination in the first place. In the present article, we
have attempted to present a conceptual framework that may help to answer this
question. Specifically, judges may distinguish between a contaminating source
and the target source of accessibility much in the same way they distinguish
between the sources of other cognitive outcomes. Although this framework
remains speculative to some extent and clearly requires more empirical scrutiny, it
is quite consistent with the current findings on the consequences of self-generated
primes. It may thus prove to be a fruitful starting point for an examination of the
psychological processes that underlie the detection of bias in social judgment.
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