Subliminal influencing in advertising: does it...
Transcript of Subliminal influencing in advertising: does it...
Subliminal influencing in advertising: does it work?
Eva Van den Bussche, Gigliola Brintazzoli, Natacha Deroost & Eric Soetens
Colloquium 16-06-2011
6/23/2011 1Herhaling titel van presentatie
Overview
• Can subliminal information influence our behavior…
• …in an experimental context? (PART I)
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• …in an experimental context? (PART I)
• …in a more real-life/advertising context? (PART II)
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Part I
Can subliminal information influence our behavior in an experimental context?
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experimental context?
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Overview Part I
• Early demonstrations
• Masked priming paradigm
• Prime awareness
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• Prime awareness
• Meta-analysis
• Conclusion
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Early demonstrations
• Can subliminally presented information influence our behaviour?- Controversial
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- Controversial
- Long history
- Subliminal = ideas below the “limen” or threshold for consciousness (Herbart, 1776-1841)
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Early demonstrations
• First empirical studies:
1. Peirce & Jastrow (1884):
�Conclusion: even when claiming to be Wich Wich
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�Conclusion: even when claiming to be unaware of any difference (score=0), subjects could still discriminate the two pressures above chance level!
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Pressure 1 Pressure 2Wich
pressurewas the strongest?
Wichpressurewas the strongest?
0 1 2 3 P1 P2
“No preference, nonsensical answer”forced-choice discrimination
task
Early demonstrations
2. Sidis (1898):
5 S Digit orletter?
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�Conclusion: even when claiming seeing only a dim, blurred spot, subjects could discriminate letters and digits AND identify them above chance level!
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5 S letter?
Masked priming paradigm
• Can subliminally presented information influence our behaviour?- Subliminal perception = a stimulus is
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- Subliminal perception = a stimulus is demonstrated to be invisible while still influencing thoughts, feelings, actions, learning or memory (Kouider & Dehaene, 2007)
- How do we measure subliminal perception today?
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Masked priming paradigm
�Masked priming paradigm (Marcel, 1983)
17ms ##
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Larger than 5Smaller than 5
17ms
33ms
480ms
##
6
##
Masked priming paradigm
Congruent
condition
Incongruent
condition
Prime 6 1
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Prime 6 1
Target 9 9
Both > 5
Faster RTs
One <, one > 5
Slower RTs
Difference (RT_I - RT_C) = priming effect
Masked priming paradigm
• 1983: Masked priming paradigm (Marcel)
• 1986: Criticism (Holender) � are we really
measuring subliminal/unconsciousperception? Inadequate measures of prime
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perception? Inadequate measures of prime awareness!
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Prime awareness
• Prime awareness assessment:
1. Subjective threshold � self-report (e.g.:
“Were you aware of the prime”)
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2. Objective threshold � discriminative abilities � post-hoc post-test– Identification: identify the prime
– Forced choice absent/present: was there a prime?
– Forced choice categorization: classify the prime
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Prime awareness
• How “fast” will a method conclude that the primes were unconscious?1. Subjective report
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2. Prime identification
3. Forced choice absent/present, forced choice categorization
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Preferred! If a priming effect is observed AND the primes could not be perceived above chance, most strict evidence of truly unconscious/subliminal priming!
Meta-analysis (Van den Bussche et al., 2009, Psych Bull)
• Mid-1990s: methodological improvements (Dehaene, Greenwald) � more reliable
masked priming paradigms
• From then on: numerous experimental
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• From then on: numerous experimental studies using the masked priming paradigm
�Statistically combine published and unpublished data using meta-analytic techniques
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Meta-analysis (Van den Bussche et al., 2009, Psych Bull)
• Search criteria: Published between 1983 – 2006 inEnglish, Dutch, French or German
• Search string: (SEMANTIC OR ASSOCIATIVE) AND (PRIMING OR PRIME) AND (MASKED OR
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(PRIMING OR PRIME) AND (MASKED OR SUBLIMINAL OR UNCONSCIOUS OR AUTOMATIC)
• Four databases were searched (WoS, ScienceDirect, PubMed, PsycInfo)
• Cross-references, reviews, experts
• 749 published articles were selected
• Two reviewers coded these articles using 7 criteria
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Meta-analysis (Van den Bussche et al., 2009, Psych Bull)
• Inclusion criteria: 1. Prime-target relation of a semantic nature in the visual domain (e.g. cat - dog)
2. Primes had to be presented subliminally
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3. Semantic categorization, lexical decision or naming task
4. Standard priming procedure
5. Centrally presented single word or symbol primes
6. Healthy sample and N>1
7. Sufficient statistical information to compute an effect size
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Meta-analysis (Van den Bussche et al., 2009, Psych Bull)
• 46 published and 8 unpublished studies containing 156 separate conditions
• Effect sizes were computed:
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• Effect sizes were computed:
RT (unrelated trials) – RT (related trials)
ES =
SD
– ES = 0: no effect
– ES > 0: positive ES (~ priming effect)
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Meta-analysis (Van den Bussche et al., 2009, Psych Bull)
• Effect sizes: Overall mean ES = 0.80 (CI: 0.60-1.00)
3,5
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-1,5
-0,5
0,5
1,5
2,5
Effect Sizes
Conclusion Part I
• Strong and robust subliminal priming effects across the experimental literature
• Subliminal information can influence
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• Subliminal information can influence our behavior… in an experimentalcontext!
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Part II
Can subliminal information influence our behavior in an real-life/advertising context?
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real-life/advertising context?
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Overview Part II
• Early demonstration
• People’s perception
• Time-course of subliminal priming
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• Time-course of subliminal priming
• Subliminal priming applied
• Our approach
• Conclusions
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Early demonstrations
• Vicary (1957): subliminal messages “drink coca-cola”, “eat popcorn” �
increased product sales
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increased product sales
• Enormous impact on public opinion:
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Early demonstrations
• Subliminal advertising was banned in many countries
• Vicary had falsified data
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• Vicary had falsified data
• Impact on public remained
• Subliminal advertising is still being used today � McDonald’s
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People’s perception
• Consumers:- are familiar with subliminal advertising (74-81%)
- believe it is being used (68-81%)
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- believe it is being used (68-81%)
- believe it “works” (72%)
• Significant positive correlation with education
Zanot et al., 1983; Synodinos, 1988; Rogers & Smith, 1993
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People’s perception
• Our study (in prep):
- N=99, psychology students, mean age = 18.7, 89% female
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- Participants received definition of experimental subliminal perception
- 6 questions assessing their perception on these kinds of effects in a daily life and advertising situation
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People’s perception
• Our study (in prep):1. Unconscious influencing (UI) is present in daily life: 99%
2. People in general are susceptible to UI in daily life: 92%
3. I am susceptible to UI in daily life: 91%
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3. I am susceptible to UI in daily life: 91%
4. UI is is being used in advertising: 95%
5. People in general are susceptible to UI in advertising: 82%
6. I am susceptible to UI in advertising: 68%
� Difference between men (27%) and women (73%)
(p= .002)!
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People’s perception
• Actual application of unconscious advertising:
- Rogers & Seiler (1994) questioned 256
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- Rogers & Seiler (1994) questioned 256 American advertising companies about whether they had ever used UI
- 91% NO, 8% did not understand the concept of UI correctly, only 1 firm had used it “as a prank”
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People’s perception
• Conclusion:
• People are familiar with subliminal advertising, they believe it is being
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advertising, they believe it is being used and they believe it works
• BUT: companies are not using it
� Discrepancy between the perception
of people and the actual use!
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Time-course of subliminal priming
• Still the question remains: does it work?
• Generalizing findings made in an exp
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• Generalizing findings made in an exp context to a more real-life situation is problematic � time-course of
subliminal priming
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Time-course of subliminal priming
�Masked priming paradigm
17ms ## SOA = 50ms
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Larger than 5Smaller than 5
17ms
33ms
480ms
##
6
##
50ms
Time-course of subliminal priming
• Exp context: subliminal info (prime) and behavior undergoing the influence of it (response to target) follow each other very closely in time
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closely in time
� prime exerts its influence almost
immediately
• Meta-analysis: average SOA = 128ms (max = 784ms)
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Time-course of subliminal priming
• Subliminal priming is short-lived!
• Priming drops to a non-significant value within a few hundreds of milliseconds (Forster & Davis, 1984; Greenwald et al., 1996; Ferrand, 1996)
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Davis, 1984; Greenwald et al., 1996; Ferrand, 1996)
�Casts serious doubt on its effectiveness in everyday life and advertising
�Subliminal info (an ad) and the behavior undergoing the influence of this info (buying the product) are much farther apart
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Subliminal priming applied
• Still, some studies have successfully applied subliminal priming in more real-life contexts
• Karremans et al. (2006):
- Subliminally primed with “Lipton Ice” or “Npeic
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- Subliminally primed with “Lipton Ice” or “NpeicTol” (23ms + masked)
- Questions:- If you were offered a drink now, what would you prefer (Lipton Ice or Spa Rood)
- If you would sit on a terrace now, how likely is it that you would order Lipton Ice/Coca Cola/Spa Rood (scale 1-7)
- I would like to drink Lipton Ice/Coca Cola/Spa Rood at this moment (scale 1-7)
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Subliminal priming applied
• Karremans et al. (2006):
- Increased choice for, and intention to, drink Lipton Ice, but only for thirsty participants
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- See also Strahan et al., 2002; Bermeitinger et al., 2009
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Subliminal priming applied
• Consumer choices can be influenced by subliminal primes that could help fulfill a need, but only if the consumer is already deprived!
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deprived!
- Veltkamp et al. (2011): even when no deprivation is present, subliminal conditioning can motivate consumers as if they were deprived
- Verwijmeren et al. (in press): subliminally priming an habitual brand has no effect, and a primed brand can lead to increased choice even at the expense of an habitual brand
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Subliminal priming applied
• Can we conclude that subliminal influencing in a real-life/advertising situation works?
• Let’s not jump to conclusions just yet…
• Methodological issues:
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• Methodological issues:
- Prime awareness assessment
- Time-course: prime and target still very close in time, laboratory context
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Our approach
• Aim: examine whether subliminal influencing can be effectively and reliably implemented in more everyday life and advertising situations, using strict methodology
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situations, using strict methodology
• New studies:1. A replication of Karremans et al. (2006)
2. A brand study
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1. A replication
• First aim: replicate Karremans et al.’s (2006) study
• Method: Identical replication, except: - We assessed level of thirst at t0 and t1
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- We assessed level of thirst at t0 and t1
- We used a more strict prime awareness assessment (i.e. categorize subliminal primes as word or non-word)
- Same subjects participated in actual experiment AND post-hoc prime awareness test
- N = 28
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1. A replication
• Results:
- Prime awareness: 43% � subliminal!
- No differences between “Lipton Ice” group and control group with regards to choice for and
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control group with regards to choice for and intention to, drink Lipton Ice
- No differences between thirsty and non-thirsty subjects
- BUT: “Lipton Ice” group showed a significant increase in thirst (p = .007), compared to the control group (p = .11)
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1. A replication
• Why were we unable to replicate Karremanset al. (2006)?
- Power?
- Difference in prime visibility?
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- Difference in prime visibility?
- Role of habits: 50% of our participants indicated Lipton Ice as their favorite brand (cf. Verwijmeren et al.)
- Can subliminal priming induce a deprivation?
� Requires further investigation!
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2. A brand study (Brintazzoli et al., in prep)
• Idea = back to basics!
• Design an experiment very similar to a typical masked priming study
BUT: with more real-life stimulus
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• BUT: with more real-life stimulus material
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2. A brand study (Brintazzoli et al., in prep)
• Stimuli• Typical masked priming experiment
• Primes = 10 very familiar brand logos �
selected in a pilot study
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selected in a pilot study
• Targets = letter strings
• Task: decide as fast as possible whether the target is a word (or brand name) or a nonsensical non-word
• 2 versions: conscious (17ms) or unconscious (13ms)
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2. A brand study (Brintazzoli et al., in prep)
• 5 conditionsa) related brand: - MCDONALD’S
b) unrelated brand: - LACOSTE
c) related non-brand: - HAMBURGER
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c) related non-brand: - HAMBURGER
d) unrelated non-brand: - CAR
e) non-word: - NOOLWEF
� 400 trials (50% word and 50% non-word)
� Only 200 word trials were analyzed
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2. A brand study (Brintazzoli et al., in prep)
• Prime visibility• Objective forced choice categorization test
• Conscious version (N=29):
- Subjects correctly categorized 75% of the primes
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- Subjects correctly categorized 75% of the primes
- d’ =1.56, t(38)= 9.43, p< .001
• Unconscious version (N=19):
- Subjects correctly categorized 52% of the primes
- d’ = 0.19, t(18)= 2.28, p= .035, no correlation with priming
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2. A brand study (Brintazzoli et al., in prep)
• Results
530
540
550
**
**
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480
490
500
510
520
brand non-brand brand non-brand
conscious unconscious
RT (ms)
related
unrelated
**
2. A brand study (Brintazzoli et al., in prep)
• Discussion
• Brand logos possess the power to prime their brand names and, remarkably, words associated to the brand
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associated to the brand
• primes “McDonald's”, but also “hamburger”!
• However, this only occurred when they were presented above the consciousness threshold!
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Conclusion Part II
• Real-life primes only elicited priming when they were presented consciously
• BUT: what do we define as “conscious” and “subliminal”???
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• Exp context: strict methodology to assure prime invisibility required!
• Is there a consensus in this more applied field? Is it the same as in the exp field? Should it be?
• What are we studying? What do we want to study?
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Conclusion Part II
• Future studies:1. More laboratory/experimental studies:
- Focus on strict design: compare “conscious” versus “unconscious”
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versus “unconscious”
- Different stimulus material, tasks,…
- Influence on decision-making, choice behavior
- Still only short-lived effects � longevity of
subliminal priming?
2. What about field studies?
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Conclusion
• Can subliminal information influence our behavior…
• …in an experimental context? YES!
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• …in an experimental context? YES!
• …in a more real-life/advertising context? ???
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Contact
Eva Van den Bussche
Vrije Universiteit Brussel
Department of Psychology
Pleinlaan 2
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Pleinlaan 2
1050 Brussels
Belgium
http://homepages.vub.ac.be/~evdbussc//
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