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Journal of Experimental Social Psychology xxx (2008) xxx–xxx
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The hidden persuaders break into the tired brain
q
Christina Bermeitinger
a,
*
, Ruben Goelz
a
, Nadine Johr
a
, Manfred Neumann
a
,
Ullrich K.H. Ecker
b
, Robert Doerr
a
a
Saarland University, Department of Psychology, Campus A2 4, D – 66123 Saarbruecken, Germany
b
School of Psychology, University of Western Australia, Crawley, Australia
article info
abstract
Article history:
Received 30 July 2007
Revised 22 September 2008
Available online xxxx
There is a long-lasting debate on whether subliminal advertising actually works. In this context there are
some studies suggesting that subjects’ motivation is a crucial point. Karremans et al. [Karremans, J. C.,
Stroebe, W., & Claus, J. (2006). Beyond Vicary’s fantasies: The impact of subliminal priming and brand
choice. Journal of Experimental Social Psychology, 42, 792–798] showed that subjects were influenced in
their intention to drink a specific brand of soft drink by a subliminally presented brand prime, but only
if they were thirsty. In the present study, we adapted their paradigm to the concept of ‘concentration’ and
embedded the subliminal presentation of a brand logo into a computer game. Actual subsequent con-
sumption of dextrose pills (of the presented or a not presented brand) was measured dependent on
the level of participants’ tiredness and the subliminally presented logo. We found the same pattern as
Karremans et al. (2006): only tired participants consumed more of the subliminally presented than the
not presented brand. Therefore, the findings confirm that subjects are influenced by subliminally pre-
sented stimuli if these stimuli are need-related and if subjects are in the matching motivational state.
2008 Elsevier Inc. All rights reserved.
Keywords:
Subliminal priming
Subliminal persuasion
Advertisement
Subliminal advertising
Need-related subliminal stimuli
Level of tiredness
Motivation for concentration enhancement
Introduction
Karremans et al. (2006)
showed that some of Vicary’s fantasies
are maybe actually not so farfetched. In their first experiment,
Kar-
remans et al. (2006)
presented a subliminal stimulus – for the
experimental group the brand name ‘‘Lipton Ice”, for the control
group the neutral string ‘‘Npeic Tol” – 25 times within a visual
detection task. Afterwards, participants had to make a virtual
choice between Lipton Ice and Spa Rood, a common mineral water.
Then, they answered questions about their intention to drink Lip-
ton Ice, Coca Cola, and Spa Rood. Finally, the level of thirstiness
was measured with two further items. There was a positive associ-
ation between the amount of thirst and the likelihood to choose
Lipton Ice (compared to Spa Rood) and between the amount of
thirst and the intention to drink Lipton Ice only in the Lipton Ice
prime condition, not in the ‘‘Npeic Tol” prime condition. In a sec-
ond experiment, the authors manipulated the amount of thirst
with a salty sweet (to increase feelings of thirst) for half of the par-
ticipants. Afterwards, subjects ran through exactly the same course
as in the first experiment. The main findings could be replicated:
the subliminal presentation of a drink’s name increased the
choice-probability for this drink and the intention to drink this
beverage only for thirsty individuals.
The study is perfectly in line with assumptions (and research
which confirms these assumptions) that one can be subliminally
influenced only if one is in a corresponding state with a selective
vigilance (see
Bruner & Postman, 1947
); that is, if the prime is in
relation to one’s current goals or needs (e.g.,
Brand, 1978; Strahan,
Spencer, & Zanna, 2002; Strahan, Spencer, & Zanna, 2005
; and even
Vicary himself assumed that in 1958, see
Rogers, 1993
).
Recently,
Karremans, Stroebe, and Claus (2006)
revived the debate
about subliminal persuasion. They connected the subliminal priming
of a brand name and the choice of this brand over control brands with
participants’ goals or needs: only thirsty participants (who were
thought to have the specific goal to quench their thirst) chose the
primed drink over the others more often. Considering the history of
findings around subliminal persuasion, to replicate and even extend
or generalize the found effect seems both challenging and vital.
Indeed, there is a long-lasting debate on the possibilities and
boundaries of subliminal advertising (for reviews, see
Dijksterhuis,
Aarts, & Smith, 2005; Theus, 1994
). The well known story of the
marketing expert James Vicary represents a milestone of this de-
bate. He claimed that he had increased the sales of popcorn and
Coca Cola by 57.7% and 18.1% after the subliminal presentation
of the slogans ‘‘Drink Coca Cola” and ‘‘Eat Popcorn” in a movie
(e.g.,
Brand, 1978; Henderson, 1957
). By 1962 at the latest, this
was exposed as a publicity hoax. Nevertheless, till today the story
is living as a modern legend (e.g.,
Pratkanis, 1992; Rogers, 1993;
Rogers & Smith, 1993
).
q
The research reported in this article was supported by intact GmbH (Hessenweg
10, D – 48157 Muenster,
who sponsored the dextrose
pills. We thank Dirk Wentura, Christian Frings, Andrea Paulus, Michaela Rohr, Joel
Cooper and one anonymous reviewer for helpful and detailed comments on an
earlier version of this paper.
* Corresponding author. Fax: +49 681 302 4049.
E-mail address:
(C. Bermeitinger).
0022-1031/$ - see front matter 2008 Elsevier Inc. All rights reserved.
doi:10.1016/j.jesp.2008.10.001
Please cite this article in press as: Bermeitinger, C., et al. The hidden persuaders break into the tired brain. Journal of Experimental Social
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C. Bermeitinger et al. / Journal of Experimental Social Psychology xxx (2008) xxx–xxx
The results of
Karremans et al. (2006)
represent a serious example of
subliminal manipulation of choice behavior with scientificmeans after
a long periodwith hundreds ofmassmedia papers that mostly pursued
this question only insufficiently (e.g.,
Pratkanis & Greenwald, 1988
).
But one could argue that the study is only one more study amongst
the hundred others which were – with random assignment – some-
times able to show subliminal persuasion and sometimes not.
Brannon
and Brock (1994)
described the problem around the lacking reproduc-
tion of a subliminal persuasion effect, fittingly, as a script for a drama
with three acts: first, observation of an effect in the field; second, dem-
onstration of the effect in a laboratory analogue; third, subsequent fail-
ure to reproduce the effect. Therefore, the vast majority of the
psychological community concluded that subliminal persuasion does
not and could not work (for example
Broyles, 2006; Dijksterhuis
et al., 2005; George & Jennings, 1975; Moore, 1988; Pratkanis & Aron-
son, 1992; Pratkanis & Greenwald, 1988; Trappey, 1996
).
Given the lack of supporting evidence, a replication of
Karremans
et al. (2006)
findings is urgently needed. Besides the importance to
replicate their effect, however, the study leaves open questions
and, at one point, shares a common problem that many previous
studies have been criticized for; that is, the test of stimuli’s sublim-
inality (e.g.,
Beatty & Hawkins, 1989; Brand, 1978; Brannon & Brock,
1994;Merikle, Smilek, &Eastwood, 2001; Saegert, 1979
). This seems
to be especially important considering the fact that prime duration
in their study was quite long (23 ms). There are a lot of studies in
which at least some participants showed high performances in di-
rect prime detection tests with even shorter presentation times of
17 ms (e.g.,
Greenwald, Draine, & Abrams, 1996
).
an equivalent to the drinks in the
Karremans et al. (2006)
study, we
chose dextrose pills – a popular means of concentration enhancement
in achievement situations.
Second, we did not measure participants’ intention to consume a
product, but their actual consumption (of a primed and a non-
primed ‘product’) within the course of the experiment. We con-
sider this a more sensitive and valid measure than the virtual
choice of one of two alternatives (see also literature on the inten-
tion-behavior gap; for an example in a purchasing context, see
Miniard, Obermiller, & Page, 1983
). First, real consumption behav-
ior is probably less influenced by strategical thinking than virtual
choice behavior. Second, we can analyze the behavior of one per-
son regarding both primed and non-primed ‘brands’. And finally,
it allows us to measure behavior over a longer period of time,
and also after participants have made some experience with the
different ‘products’.
A third difference is that we did not use common brands.
The two logos we used were designed especially for this study.
Additionally, one logo was subliminally presented to one half of
the subjects, the other logo was subliminally presented to the
other half of the subjects. This counterbalancing allowed us to
compare consumption behavior between both ‘brands’ instead
of comparing the subliminally presented brand and a further
control brand (as in
Karremans et al., 2006
). It has been dis-
cussed that influencing someone’s consumer behavior may be
simpler when concerned with neutral stimuli in comparison to
already familiar brands (e.g.,
Dijksterhuis et al., 2005
). Neverthe-
less, we chose this procedure because our interest was the
manipulation of consumer behavior in terms of a relative com-
parison of two (novel) brands, not regarding a change of an a
priori preference.
Fourth, after the main experiment and for each participant,
we ran a direct test to objectively assess discrimination perfor-
mance regarding the two logos, as recommended by
Merikle
et al. (2001)
.
Karremans et al. (2006)
ran a direct test with sep-
arate participants, asking them to report the subliminally pre-
sented word. Our approach was to ask subjects to make
several two-alternative forced choices – select the logo that
was subliminally presented earlier –, which we consider a sim-
pler and thus more sensitive task. Hence, if a participant suc-
cessfully differentiated between the two logos (i.e., detected
the previously presented logo), we concluded that behavior
may have been based on some supraliminal details. Such an
individual measure of discrimination performance also allowed
us to check whether an effect hinges on participants with good
or bad performance.
Last but not least, we embedded the subliminal presentation in
a computer game, which constitutes a less artificial context than
those used in most of the previous studies.
The present research
In the present study, we wanted to take up the experiments
from
Karremans et al. (2006)
and conceptually replicate their find-
ings. Additionally, we wanted to expand their results; in particular,
we measured the primes’ subliminality in the actual prime study’s
participants and we measured actual consumption behavior rather
than just the intention to behave.
First of all, we chose a needother than thirst to go one stepbeyond
simple physiological needs. We decided to use the concept of ‘con-
centration’. Tired persons need to put more effort into a task in an
achievement situation than fit persons. Therefore, tired persons
should have the motivation to enhance their concentration. Of
course, the first wish of a tired personwould be to take a rest or sleep
for awhile. Butmost often (in the lab and in everyday life aswell) this
possibility is no real alternative. In the lab, participants give their
consent to concentrate and do the best they can. And in everyday life,
you only have to imagine a night-time car journey, duringwhich it is
vital to focus on the task andmobilize your reserve resources despite
fatigue. We call this motivation the ‘motivation for concentration
enhancement’ (MfCE) and we assume that tired participants in par-
ticular have this need. This assumptionwas tested and corroborated
with 25 subjectswho did not participate in themain experiment.
1
As
Methods
1
We tested the relation of the level of tiredness and MfCE. Both were continuous
variables based on participants’ self-ratings. Materials and the procedure were similar
to the main experiment but without the direct test of discrimination performance
concerning the subliminal stimuli and without different choices of primed or non-
primed pills: the dextrose pills were offered in only one bowl which was not labeled
with any logo, and the bowl contained 20 dextrose pills. Subjects played the computer
game and were then given 28 questions mainly targeting their effort or strategies
during the game and how supporting the consumption of dextrose was. Among these,
the critical question appeared: ‘‘How strong was your need to enhance your level of
concentration before or during the game?” [2 = very,
2 = not at all]. Overall,
participants had no significant motivation for concentration enhancement, M = 0.28
(SE = 0.25), t(24) = 1.13, p = .27. Yet, most importantly, the correlation between the
level of tiredness and MfCE was significant, r = .52, p < .01; the more tired participants
were, the higher was their need to enhance their concentration level. Thus, the result
is perfectly in line with our prediction.
Participants
The sample consisted of 64 (18 male, 46 female) participants
from Saarland University (Md = 21 years, ranging from 19 to 49).
They received experimental credits for their participation and
had the chance to win vouchers for the movie theater. All partic-
ipants had normal or corrected to normal vision. Three subjects
were excluded from the analysis because of very low scores
(below 3 points) on the Inventar Komplexer Aufmerksamkeit
(INKA, inventory for complex attention;
Heyde, 2000
), testing
concentration performance (see below); these subjects likely
did not understand instructions or were not motivated to follow
them.
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Fig. 1. Black-and-white versions of the stimuli designed for the subliminal presentation. (a) logo A, (b) logo B, (c) mask created from an equal number of parts of both logos.
Design
Procedure
The design comprised factors ‘subliminal prime’ (logo A vs. logo
B) and ‘level of tiredness’ (continuous variable based on partici-
pants’ self-rating). Each participant was shown either logo A or
logo B. The number of consumed dextrose pills from product A
and product B (‘consumption’) served as the dependent variables.
Participants were tested in groups of up to four people. The
experiment was run on IBM-compatible PCs using E-Prime soft-
ware and 17’’ CRT-monitors with a refresh rate of 100 Hz. Unless
otherwise noted, all instructions and tasks were given on the com-
puter screen.
In the first phase, subjects gave their consent to participate vol-
untarily and with their full engagement. Participants were told that
the goal of the experiment was to test if the individual self-deter-
mined consumption of dextrose influenced concentration and per-
formance in a computer game. They were told that we had two
different sponsors for the dextrose pills (which nevertheless had
similar taste and composition), such that they had two different
products to choose from. Subjects were additionally motivated
with the chance to win vouchers for the movie theater, which were
given to the participant with the highest score within their group.
In the second phase, participants were requested to answer
some questions about their actual state, their leisure time, and
their consumption of various substances (e.g., coffee, tea, or energy
drinks) in concentration-demanding situations. Within these ques-
tions, participants’ tiredness was measured with two five-point
items: ‘‘Today I am ...”[
2 = well rested, 2 = not well rested], ‘‘At
the moment I am feeling ...”[
2 = fit, 2 = tired]. The scores on
these items were averaged to create an index of tiredness.
In the third phase, participants were acquainted with the com-
puter game with appropriate instructions and a two-minute prac-
tice block. This practice block was exactly the same as the
following game blocks within the fifth phase (see below), except
that the score was not included into the overall score of the partic-
ipants. Within each block (i.e., during the ongoing game), there
were three sequences. In the first sequence A, which lasted 30 s,
the word ‘‘Konzentration” (concentration; 5.5 cm in width,
0.5 cm in height) was subliminally flashed on the screen in red to
enhance or trigger subjects’ motivation for concentration. The
word was presented at the same position as the subliminally pre-
sented logo; presentation time was 10 ms, with an inter-trial inter-
val (ITI) of 3000 ms. During the second sequence B (30 s), the word
‘‘Konzentration” and the subliminally presented logo were pre-
sented alternately: Presentation started with the logo (i.e., the
prime; 10 ms), which was replaced by the mask (10 ms); after an
ITI of 3000 ms, ‘‘Konzentration” was presented for 10 ms, and so
on. In the last sequence C (60 s), only the subliminal prime
(10 ms) followed by the mask (10 ms) were presented consecu-
tively with a 3000 ms ITI.
In the fourth phase, participants received the paper and pencil
version of the INKA (
Heyde, 2000
), a test of concentration and
attention (i.e., the quality of information processing).
2
The test
Materials
We designed 10 colored logos (eachwith a graphical background
and the writing ‘Dextro’) that were tested in a pretest with 39 sub-
jects who did not take part in the main experiment. Two logos (for
black-and-white versions see
Fig. 1
) were selected as subliminal
stimuli because of comparable preferences in the pretest. Both logos
could be imagined as logos for a dextrose brand and they were cho-
sen equally often as the preferred logo. The logos did not differ with
regard to their size (7.9 cminwidth, 5.8 cminheight) and theirmean
luminance. The dominant colors of both logoswere black, red, white,
and yellow. Amask was created by decomposing each of the two lo-
gos into 40 parts. Then, 20 parts of each logo, respectively, were new-
ly put together (ensuring that darker partswere predominantlyused
for outer areas of the image, as in the original logos; for a black-and-
white version see
Fig. 1
c). Dextrose pills with a diameter of 2 cm, a
weight of 2 g, and a slight citric taste served as products that could
be consumed during breaks. They were offered in two small bowls
positioned side-by-side on the left-hand side of the monitor; the
bowls were covered until the first consumption break. Each bowl
contained 10 pills; one of the logos (defining product A and product
B, respectively) was pasted onto each bowl; the positioning of bowls
(i.e., the assignment of logos to left/right bowls) was counterbal-
anced across subjects.
For the presentation of the subliminal logos, we designed a sim-
ple two-dimensional jump-and-reach computer game in E-Prime
(version 1.1, SP 3, Psychology Software Tools, Inc., Pittsburgh, PA,
USA). In this game, a green avatar manikin (3 cm in height) walked
on a gray wall (which occupied the lower 6 cm of the screen) and
jumped when the up-arrow-key was pressed. By doing so, the man-
ikin could collect bundles of banknotes that flew into the screen from
the right-hand side. For each collected bundle, one point was added
to the playing score (which was shown in the right-upper corner).
Additionally, the manikin had to jump over campfires that also
emerged on the right-hand side. Two points were taken off the score
if the manikin did not succeed in doing so. To make it more difficult,
the speed of the incoming objects was increased with increasing
duration of the game. The background consisted of flickering flames
to conceal the subliminal stimulus presentations.
The logos and the mask were presented to the upper right of the
manikin. This position was chosen because it was the place most
likely attended by participants because the game objects (i.e., notes
and fires) appeared on the right-hand side.
2
This test requires participants to scan rows of consonants for specified consonants
and to transform these into assigned letters via a transformation index.
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was in line with the cover story and was introduced to further focus
subjects on the need for concentration. Instructions were given ver-
bally and on the test sheets. The test lasted about 15 min.
The fifth phase comprised the main part of the experiment.
There were four game blocks of 2 min each. The procedure was
the same as in the practice block. Altogether, in each of the four
blocks, the word ‘‘Konzentration” was presented 14 times and
the subliminal prime was presented 24 times. Between the blocks,
there were consumption breaks of about 1 min each. During these
breaks, participants had the chance to consume the dextrose pills.
It was emphasized particularly that it was at participants’ discre-
tion whether, how many, and which pills they chose to consume.
After the last game block and in the sixth experimental phase,
participants answered some questions about the game and the
dextrose brands. They were then informed about the presentation
of subliminal logos and asked if they had perceived any aspects of
the primes or masks.
This debriefing was followed by the seventh phase featuring a
direct test of discrimination performance regarding the sublimi-
nally presented logos. Each trial was set off by a key press, and then
a short sequence of the game was shown. Participants were in-
structed not to move the manikin but instead to attend to the posi-
tion where the subliminal logo was presented. First, a green dot
was flashed for 10 ms at that position. After a 130 ms ‘‘blank” inter-
val, the dot was repeated for a further 10 ms. Then, after another
130 ms, one of the two logos appeared for 10 ms, followed by the
mask for a further 10 ms (note that the time parameters of logo
and mask presentation were exactly the same as in the game
blocks). Finally, the two logos were presented next to each other
on a white background and subjects had to decide (using the
mouse) which logo they had just seen. This sequence was repeated
50 times, with random assignment of logos; that is, half of the tri-
als contained the logo presented in the game, the other half con-
tained the logo that was not presented.
Finally (phase eight), participants were fully debriefed and they
were asked to maintain confidentiality concerning the true pur-
pose of the experiment. The score of each participant was read
from the monitor and the subject with the highest score was re-
warded the cinema voucher. After the participants had left, the
number of consumed pills from each of the two bowls was
counted.
scores – number of consumed pills of the primed logo minus num-
ber of consumed pills of the non-primed logo. Thus, positive values
indicate more consumption of the primed product than the non-
primed product. These difference values were linearly regressed
onto the level of tiredness (from
2 = not-tired to 2 = tired). The
analysis revealed a significant positive association between tired-
ness and the difference of consumed pills, b = .34, t(60) = 2.79,
p < .01 (see
Fig. 2
) – tired subjects consumed more of the primed
product compared to the non-primed product. The constant was
significant as well, t(60) = 2.11, p < .05. The analysis yielded pre-
dicted values with a 95%-interval of confidence not including zero
for tiredness values above
0.25 (see
Fig. 2
). That is, even for those
participants who were neither especially tired nor especially
‘not-tired’, it can be expected that the consumption of the primed
product exceeds the consumption of the non-primed product.
The above regression analysis corresponds to an interaction be-
tween type of logo (primed vs. non-primed) and tiredness. Thus,
we calculated the simple effects of tiredness separately for primed
and non-primed logos. These analyses revealed a significant posi-
tive association between tiredness and the amount of consumed
pills only for the primed logo, b = .30, t(60) = 2.44, p < .05, not for
the non-primed logo, b =
.04, t < 1 (see
Fig. 3
).
4
Discussion
With the experiment we conceptually replicated the findings of
Karremans et al. (2006)
. Only participants with a specific need or
motivation chose the subliminally presented motivation-related
product more often. While
Karremans et al. (2006)
used the basic
need of thirst as the predictor, we transferred the problem to the
motivation for concentration enhancement, which is higher when
participants are tired – as demonstrated with an independent sam-
ple (see footnote 1). Thus, we extended Karremans et al.’s findings
to arrive at a broader understanding of motivational states.
As expected, only tired participants consumed more pills of the
primed brand than the non-primed brand; not-tired participants
consumed equal amounts of both products. Furthermore, the effect
is clearly based on the additionally consumed primed-brand pills
in the tired subsample; there was no difference between tired
and not-tired participants regarding the consumption of the non-
primed product. Thus, only the consumption of the subliminally
primed product was influenced – not the consumption of the
non-primed product. However, we do not know how the general
Results
Direct test of discrimination performance
4
To present the more conventional results of an ANOVA and to exclude
interpretations concerning possible material differences, we additionally conducted
a repeated measures MANOVA with the factors ‘subliminal prime’ (logo A vs. logo B),
‘tiredness’ (tired vs. not-tired), and ‘bowl arrangement’ (A left and B right vs. B left
and A right), and the number of consumed pills from logo A and logo B as the
dependent variables. The majority of participants (n = 40) had negative tiredness
scores. We labeled this subsample ‘not-tired’. There were 14 participants with
positive values. These subjects were labeled as ‘tired’. Seven subjects had a tiredness
score of zero, that is, they considered themselves neither tired nor not-tired. This
subsample was labeled ‘neither-nor’. Overall, participants had a mean tiredness of
M =
0.60 (SE = 0.13), which differed significantly from zero, t(60) = 4.68, p < .001,
and indicates that they were on average rather non-tired. In the MANOVA, there was a
significant main effect of ‘tiredness’, F(1, 46) = 4.95, p < .05,
g
p
2
= .10; tired partici-
pants consumed M = 2.31 (SE = 0.98) more dextrose pills than not-tired participants.
Further, there was a significant interaction of ‘subliminal prime’ and ‘consumption’,
F(1, 46) = 4.70, p < .05,
g
p
2
= .09. Most importantly, these main and interaction effects
were qualified by a significant interaction of ‘subliminal prime’, ‘tiredness’, and
‘consumption’, F(1, 46) = 9.63, p < .005,
g
p
2
= .17. As seen from
Table 1
and confirming
the findings from the regression analyses, only the tired participants consumed
M = 1.7 (SE = 0.56) more pills of the primed product, t(13) = 3.07, p < .01. The
tendency of the not-tired subjects to consume M = 0.25 (SE = 0.27) more pills of the
non-primed (compared to the primed) product was not significant, t < 1. No other
main or interaction effect reached significance, all Fs<2.9, all ps > .09. Most
importantly, there was no main effect of the subliminally presented logo, no overall
difference between the consumption of products A and B, and no effects including the
factor ‘bowl arrangement’.
For some participants, the parametric signal detection sensitiv-
ity measure d
0
could not be calculated because their hit rate or false
alarm rate was either zero or one. Therefore, the non-parametric
equivalent A
0
(see
Pollack, 1970; Pollack & Norman, 1964
) was cal-
culated. A
0
ranges from one (perfect discrimination) to zero (perfect
discrimination, but reversed keys) with A
0
= .50 denoting random
responding. On average, A
0
was .47 (SD = 0.16), which did not differ
significantly from random responding, t(60) = 1.34, p = .19.
3
Consumption behavior
For the tired and not-tired participants (see footnote 4), the
mean number of consumed pills associated with logo A and logo B
are shown in
Table 1
. First, we calculated the individual difference
3
With respect to the individual 2 (presentation: logo A vs. logo B)
2 (response:
choice of logo A vs. choice of logo B) distribution, three participants had a
v
2
value
associated with p-values below .05 (all
v
2
> 4.02, all ps < .04) and another three
participants had a
v
2
value associated with p-values below .10 (all
v
2
> 2.88, all
ps < .09). Excluding these participants from the following analysis did not change the
pattern of results.
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Table 1
Mean number of consumed pills from product A and product B (standard deviation in parentheses) as a function of level of participants’ tiredness (not-tired, neither-nor, tired),
subliminal prime (logo A vs. logo B) and order of bowl arrangement (A left and B right = AB vs. B left and A right = BA).
Not-tired participants
Neither-nor participants
Tired participants
Subliminal prime
Subliminal prime
Subliminal prime
logo A
logo B
logo A
logo B
logo A
logo B
Consumption of product A
bowl order AB
2.0 (2.1)
1.8 (1.6)
0.5 (0.7)
1.0 (–)
a
4.0 (2.0)
1.0 (1.0)
bowl order BA
1.2 (1.6)
1.8 (1.3)
—
b
2.8 (2.8)
4.0 (3.0)
2.4 (1.7)
Consumption of product B
bowl order AB
1.8 (1.6)
2.1 (2.2)
1.5 (0.7)
2.0 (–)
a
2.0 (1.0)
3.3 (3.2)
bowl order BA
2.1 (2.0)
1.0 (1.2)
—
b
2.5 (1.7)
3.0 (1.0)
3.6 (2.7)
a
There is only one participant in this condition.
b
Fig. 2. Difference of consumed dextrose pills (consumed pills of the primed product
consumed pills of the non-primed product) as a function of the level of tiredness
ranging from
2 (not-tired) to 2 (tired) (bold line). Grey lines indicate the 95%-
interval of confidence; the arrow indicates the level of tiredness above which the
predicted value of the consumption difference (i.e., more consumed pills of the
primed product than the non-primed product) is significant (
a
= .05).
trose in a very specific manner, leading only to an increase in
primed-brand consumption. This is evidence that the prime af-
fected participants’ behavior rather specifically. Importantly, we
were able to demonstrate the effect of subliminal priming on real
consumer behavior (and not only on the intention to consume)
in a quite realistic context.
In contrast to
Karremans et al. (2006)
, we checked subjects’
individual prime discrimination performance directly. The low rate
of participants with above-chance performance in this discrimina-
tion task shows that the chosen presentation procedure was suc-
cessful in preventing conscious awareness of the logos.
Additionally, analyses of consumption behavior yielded essentially
the same results if participants who performed above chance in
this direct test were excluded. Hence, the explanation that the ef-
fect hinges on consciously available supraliminal information is ru-
led out.
The prime stimuli we used were neutral and non-familiar logos
that were designed especially for use in the experiment. That may
have increased the chance of finding an effect of the subliminal
logo, because the effect of both subliminal and supraliminal adver-
tising is greatest when participants’ attitude towards the adver-
tised product is indifferent (e.g.,
Brand, 1978
). Importantly,
however, logos were chosen to be equally appealing (as indicated
by pretest data), they were very similar (they displayed the same
word, they had similar colors, etc.), and each logo served as the
subliminal prime for half of the participants and as the control logo
for the other half of the participants. Consequentially, the overall
level of consumption of products A vs. B was equivalent. One can
therefore conclude that the material had equivalent a priori appeal
and that the effect did not depend on a specific logo, but on the
actually subliminally presented logo and the individual level of
tiredness. Additionally and despite claims to the contrary (
Cuperf-
ain & Clarke, 1985
), we can conclude that a subliminal stimulus
does not need to have a certain a priori familiarity to be effective
in an advertising context. In a similar vein, the present study dem-
onstrates that fairly complex stimuli can elicit subliminal manipu-
lation of behavior (which of course requires that participants’
visual system can differentiate between stimuli, cf.
Bahrami, Lavie,
& Rees, 2007
). This sheds further light on the question of how com-
plex stimuli can actually be for subliminal processing (e.g.,
Cooper
& Cooper, 2002; Greenwald, 1992
).
The embedding of the subliminal presentation into a computer
game seems to be an interesting and potentially momentous vari-
ation to earlier studies. Our task was in no way related to the con-
sumption product. This constitutes a less artificial context than
that used in most previous studies, which have used lexical deci-
sion tasks and the like. The fact that subjects played a computer
game means that they did not focus their attention on the position
where the subliminal stimuli would appear at all times, and also
that they were occupied with a more complex task (including,
Fig. 3. Consumed dextrose pills associated with the subliminally presented logo
(i.e., the primed logo) and the not presented logo (i.e., the non-primed logo) as a
function of the level of tiredness ranging from
2 (not-tired) to 2 (tired).
consumption of dextrose was affected by the subliminal prime due
to the lack of a control group which did not receive any prime.
Therefore, it is possible that the prime per se led to an increase
of dextrose consumption. Nevertheless, for tired participants, the
subliminal prime affected the consumption of (additional) dex-
Please cite this article in press as: Bermeitinger, C., et al. The hidden persuaders break into the tired brain. Journal of Experimental Social
Psychology (2008), doi:10.1016/j.jesp.2008.10.001
There is no participant in this condition.
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