Transcript Masking and subliminal priming

Supra- and subliminal priming
Piotr Jaśkowski
Department of Cognitive Psychology
University of Finance and Management, Warszawa
What is supraliminal priming?
Prime is fully visible
target
RT
congr
incongr
prime
Task: Respond with the hand the arrow points to
Source: Jaśkowski, Consc.Cogn., 2006
What is subliminal priming?
Semantic priming
Source: Dehaene et al., Nature 1998
What is subliminal priming?
Semantic priming
prime
target
V-V
six
three
A-V
6
three
V-A
six
3
V-V
6
3
Source: Dehaene et al., Nature 1998
What is subliminal priming?
Priming effect
PE = RT(incomp.) – RT(comp.)
Positive compatibility effect (PCE):
PE > 0
Negative compatibility effect (NCE):
PE < 0
Source: Dehaene et al., Nature 1998
What is subliminal priming?
Semantic priming
PCE for all conditions
Source: Dehaene et al., Nature 1998
What is subliminal priming?
Motor priming
Respond to the target’s side
RT
50 ms
comp.
target
Source: Neumann & Klotz, Att Perform.1994
incomp.
What is this talk about?
Questions to answer
• Is it possible to control subliminal
processing?
• How neutral is a neutral mask?
• Is a double dissociation a proof for
subliminal processing?
Is it possible to control subliminal processing?
Task: call the target’s color
Stroop-like task
Subliminal situation
red
33 ms
#$&%$
#####
267 ms
Supraliminal situation
red
#####
300 ms
Source: Merikle & Joordans, Consc.Cogn., 1997
Is it possible to control subliminal processing?
Stroop-like task
supraliminal
compatible condition: 25% trials
RT
red
#####
incompatible condition: 75% trials
red
comp.
#####
incomp.
subliminal
RT
comp.
Source: Merikle & Joordans, Consc.Cogn., 1997
incomp.
Is it possible to control subliminal processing?
Stroop-like task
• The reversed effect was found under the
supraliminal condition, because under this
condition participants had the possibility to
‘‘capitalize on the predictive information
provided by the primes’’.
• Strategical control can be exercised only
under supraliminal condition.
Source: Merikle & Joordans, Consc.Cogn., 1997
Is it possible to control subliminal processing?
Problem
• If there is no control over subliminal stimuli:
– It should be possible to trigger one’s response
against one’s will.
– It should be possible to trigger one’s response by
means of several subsequently presented
subliminal primes.
Is it possible to control subliminal processing?
Target
Multiple priming
Task: respond with left/right key depending on target
position.
Source: Jaśkowski et al., J.Cogn.Neurosci., 2003
Is it possible to control subliminal processing?
prime duration = 11.6 ms
target duration = 100 ms
35 ms
35 ms
35 ms
35 ms
Source: Jaśkowski et al., J.Cogn.Neurosci., 2003
Is it possible to control subliminal processing?
Condition 80/20
- 20% compatible
- 80% incompatible
Condition 20/80
- 80% compatible
- 20% incompatible
Source: Jaśkowski et al., J.Cogn.Neurosci., 2003
Is it possible to control subliminal processing?
1.00
450
400
comp
350
incomp
Percent correct
Reactiontime
time(ms)
(ms)
Reaction
0.95
0.90
comp
0.85
incomp
0.80
300
0.75
250
0.70
20-80
80-20
20-80
Source: Jaśkowski et al., J.Cogn.Neurosci., 2003
80-20
Is it possible to control subliminal processing?
Conclusions:
• Even when stimuli are subliminal
participants can control their influence on
their behavior:
– Plausibly, they can augment or damp the
subliminal influence off-line.
– A need for such a regulation partcipants can infer
from observation of their own performance.
Source: Jaśkowski et al., J.Cogn.Neurosci., 2003
Is it possible to control subliminal processing?
Correction of performance is mediated by frontal cortex
Source: Wolbers et al. Cerebral Cortex, 2005
Is it possible to control subliminal processing?
Strategical control can be
exercised only under supraliminal
condition.
Source: P. Collins, www.philcollins.co.uk
How neutral is a neutral mask?
Negative compatibility effect
•
•
A mask reduces the participants’ conscious
accessibility to the prime information, but it does not
affect response to the target provided that the mask
is neutral.
A mask is neutral if it induces no response to the
target.
How neutral is a neutral mask?
Negative compatibility effect
RT
congr
incongr
Task: Respond with the hand the arrow points to
Source: Eimer & Schlaghecken, JEP:HPP, 1998
How neutral is a neutral mask?
Negative compatibility effect
negative
RT
comp.
incomp.
positive
RT
comp.
Source: Verleger et al., JEP:General, 2004
incomp.
How neutral is a neutral mask?
A mask does not affect response to the
target provided that it is neutral.
Source: P. Collins, www.philcollins.co.uk
Is a double dissociation an evidence for subliminal processing?
NCE vs. PCE
negative (NCE)
RT
comp.
incomp.
positive (PCE)
RT
comp.
Source: eg. Klapp & Hinkley, JEP:Gen, 2002
incomp.
Is a double dissociation an evidence for subliminal processing?
•
•
NCE for masked and PCE for unmasked stimuli is a
stronger evidence than for nonconscious influences.
This dissociation shows that there are different
mechanisms underlying conscious and
nonconscious processing.
If there is a qualitative difference in performance
under the masking and nonmasking condition, it is a
strong evidence for subliminal processing.
Source: Klapp & Hinkley., JEP:HPP, 2005
Is a double dissociation an evidence for subliminal processing?
Negative compatibility effect
NCE: no masking
NCE: efficient masking
possible mask temporal positions
Source: Jaśkowski, JEP:HPP, in press
Is a double dissociation an evidence for subliminal processing?
No masking at all
Negative compatibility effect
Source: Jaśkowski, JEP:HPP, in press
Is a double dissociation an evidence for subliminal processing?
Advice 3
If there is a qualitative difference in
performance under the masking and
nonmasking condition, it is a strong
evidence for subliminal processing.
Oh, think twice...
before you conculude like this.
Source: P. Collins, www.philcollins.co.uk
How far can you go with generalization?
Arrowness
•
Have different types of priming (semantic,
perceptual, motor etc.) common features (dynamics,
persistence etc.)?
Is a double dissociation an evidence for subliminal processing?
Negative compatibility effect
mask
Source: Jaśkowski & Ślósarek, Consc.Cogn., in press
Is a double dissociation an evidence for subliminal
processing?
Advice 4
Oh, think twice...
before you try to generalize your finding
Source: P. Collins, www.philcollins.co.uk
Conclusions
• We control if our performance is or not consistent
with our goals even if the stimuli are subconsciously
processed.
• A mask is not a neutral stimulus. It is actively
processed and our behavior is corrected according
to the information the mask brings.
• Not every double dissociation is an evidence for
subliminality.
• Be careful with generalizations!