Bottom-upand top-down effectsof unconscious...

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Bottom-up and top-downeffects of unconsciousprocessingprocessing

Eva Van den Bussche & Bert Reynvoet

SCAN 16-06-2011

6/23/2011 1Herhaling titel van presentatie

Overview

• Introduction

• Bottom-up: The depth of unconscious processing

processing

• Top-down: Is consciousness necessary for cognitive control?

• A new paradigm

• General conclusions

16-06-2011 2SCAN Utrecht

Introduction

• Can unconsciously / subliminally presented information influence our behaviour?

�Masked priming paradigm (Marcel, 1983)

Larger than 5Smaller than 5

Introduction

�Masked priming paradigm

Congruent

condition

Incongruent

condition

Pag.16-06-2011 4SCAN Utrecht

condition condition

Prime 6 1

Target 9 9

Both > 5

Faster RTs

One <, one > 5

Slower RTs

Difference (RT_I - RT_C) = priming effect

Bottom-up

• Can unconsciously / subliminally presented information influence our behaviour? YES!

behaviour? YES!

• BUT: how far does this bottom-up strength reach?

• How deep can unconscious stimuli be processed?

Bottom-up

• How deep can unconscious stimuli be processed? � 2 classes of theories:

– Semantically (e.g. Dehaene et al.,

– Semantically (e.g. Dehaene et al., 1998)

– Non-semantically, but due to low-level Stimulus-Response (S-R) mappings (e.g. Damian, 2001; Kunde et al., 2003)

Bottom-up

Larger than 5!

Response = Congruent

Prime6

1. Semantic account:

Smaller than 5!

Response = Incongruent

Prime1

Response = press right

Congruent � faster RT!

Target9 Larger than 5!

Response = press left

Incongruent � Slower RT!

Bottom-up

Larger than 5!

Response =

Prime6

2. Non-semantic account:

Response =

Prime1

Congruent � faster RT!

Target9

Response = press LEFT

Incongruent � Slower RT!

Bottom-up

• BUT: formation of S-R links limited to:

– Expected stimuli (e.g. repeated primes, same format)

– Small number of stimuli (e.g. small sets, small categories)

� NO subliminal priming expected for:

unexpected stimuli, large stimulus sets, large stimulus categories

Bottom-up

• However:

- Subliminal priming for large stimulus sets, large categories (for a meta-analysis see Van den Bussche et al., 2009a, Psych Bull)

Van den Bussche et al., 2009a, Psych Bull)

- Subliminal priming for unexpected formats (Dell’Acqua & Grainger, 1999; Van den Bussche et al., 2009b; Van den Bussche et al., under review)

Bottom-up

• Conclusion:

Despite the limited bottom-up strength, unconscious stimuli can influence

unconscious stimuli can influence behavior and be processed up to a high semantic level!

~ consensus

Top-down

• But, can an unconscious stimulus modify unconscious processing by exerting top-down control?

= heavily debated!

• Subliminal processing = ‘‘a condition of information inaccessibility where bottom–up activation is insufficient … for global ignition’’ (Dehaene et al., 2006, p.3).

Top-down

• Double prediction (GNW):

1. Unconscious processes are sensitive to conscious strategic and contextual influences

influences

2. However, an unconscious stimulus itself cannot modify unconscious processing by exerting top-down control

Top-down

1. Unconscious processes are sensitive to conscious strategic and contextual influences

� Yes!

Unconscious priming can be influenced by temporal attention (Naccache et al., 2002), spatialattention (Sumner et al., 2006) and strategies, such as target set (Greenwald et al., 2003) and target notation (Kunde et al., 2003)

Top-down

• Example: Kunde et al. (2003)Targets Primes Priming?

1, 4, … 1, 4, … Yes

1, 4, … one, four, … No

� Unconscious priming effects were dependent

on the target notation (i.e. a conscious manipulation)

1, 4, … one, four, … No

one, four, … 1, 4, … No

one, four, … one, four, … Yes

Top-down

� ???

Top-down

• Our study (VDB et al., 2008, Con & Cog)

• Investigate the 2 predictions by manipulating the proportion (50-50, 25-75 or 75-25) of Arabic numbers (e.g. 1) versus

or 75-25) of Arabic numbers (e.g. 1) versus number words (e.g. “one”):

– Consciously (target level): experiment 1

– Unconsciously (prime level): experiment 2

• All other task conditions were controlled

Top-down

Congruent trial

#$#$#$33ms

$#$#$#

Larger than 5Smaller than 5

Top-down

N = 15 N = 16 N = 15 N = 16 N = 16

F(2,43) = 3.70, p = .03 F(2,44) = 0.22, p = .81

� The conscious manipulation exerted top-down control on the priming effects, but the unconsciousmanipulation did not

25% Arabic targets

75% Arabic targets

baseline 25% Arabic primes

75% Arabic primes

Arabic primes

Number word primes

N = 15 N = 16 N = 15 N = 16 N = 16

Top-down

� Yes!

� But…

Top-down

• Is consciousness necessary for cognitive control?

Yes: Ansorge et al., in press; Kunde, 2003; Merikle & Joordens, 1997; Nieuwenhuis et

Merikle & Joordens, 1997; Nieuwenhuis et al., 2001; Van den Bussche et al., 2008

No: Bodner & Masson, 2001; Cohen et al., 2009; Hughes et al., 2009; Lau & Passingham, 2007; van Gaal et al., 2008; 2010

Top-down

• Unconscious manipulations can NOT influence priming (Merikle & Joordens, 1997; Van den Bussche et al., 2008)

• An unconscious conflict can NOT induce

• An unconscious conflict can NOT induce conflict adaptation effects (Ansorge et al., in press;

Kunde, 2003)

• Unconscious errors do NOT lead to post-error slowing (i.e. remedial action to prevent future errors) (Nieuwenhuis et al., 2001)

Top-down

• Unconscious manipulations can influence priming (Bodner & Masson, 2001)

• An unconscious conflict can induce conflict adaptation effects (van Gaal et al., 2010)

• Unconscious errors can lead to post-error slowing (Cohen et al., 2009)

• Unconscious information can act as a “stop signal” and urge subjects to interrupt their ongoing response to a task (Hughes et al., 2009; van Gaal et al., 2008)

• Unconscious information can influence task selection (Lau & Passingham, 2007)

Top-down

• Aforementioned studies suffer from critical problems:

1. Objective post-hoc awareness tests which are

1. Objective post-hoc awareness tests which are heavily debated

2. Visual strength of the stimuli always critically differed in the conscious and unconscious conditions

3. Different experimental paradigms � difficult to

compare

A new paradigm

• Our current aim: investigate whether consciousness is needed for cognitive control, but using a paradigm which

control, but using a paradigm which avoids the problems demonstrated for previous studies!

• How?

A new paradigm

• Design:

#$#$#$ RED $#$#$# &&&&&How certain are you that the

colour word presented before

the target was "RED" or

"BLUE"?

Trials are divided based on prime awareness task in conscious and unconscious trials

Target

classification

"BLUE"?

1 2 3 4 5

A new paradigm

• Advantages:

1. Trial-based assessment method

2. Visual strength identical in conscious and

2. Visual strength identical in conscious and unconscious conditions

3. Paradigm can be used to examine a wide array of top-down effects (priming, conflict adaptation, …)

A new paradigm

• Disadvantages:

1. Requires many participants

2. Requires many trials (exclusion of uncertain

2. Requires many trials (exclusion of uncertain trials)

3. Takes some time to master

A new paradigm

• Does it work?

- Took many pilot studies to get it right (masks, prime duration, PAS-scale, number of trials, etc.)

number of trials, etc.)

- First “finished” study just completed!

A new paradigm

480 ms 40 ms 27 ms 2000 ms

$#$#$# RED $#$#$# &&&&&

How certain are you that the colour word RED or BLUE was presented before the coloured

symbols?

1.I am certain that I saw the colour

+Press the spacebar when you're

ready to start the next trial.Place your fingers on buttons "a"

and "p" again to be able to categorize the coloured symbols

as fast as possible

Design (320 trials):

1.I am certain that I saw the colour word RED: press button "1“2.I think I saw the colour word RED, but I am not certain: pressbutton "2”3.I did not see the colour word: press button "3”4.I think I saw the colour word BLUE: press button "4”5.I am certain that I saw the colour word BLUE: press button "5"

as fast as possible

If the symbols are red: press "a"If the symbols are blue: press "p"

p (BLUE)a (RED)

1 2 3 4 5

A new paradigm

• Results- N=60 � 24 excluded

- Conscious trials (on average 99) = subjects correctly identified the primes and were 100%

correctly identified the primes and were 100% certain

- Semi-conscious trials (on average 97) = subjects correctly identified the primes but were not certain

- Unconscious trials (on average 61) = subjects reported not being able to identify the prime

A new paradigm

• Results:- Repeated measures with condition (conscious,

semi-conscious or unconscious) and congruency (congruent or incongruent) as within-subject

(congruent or incongruent) as within-subject factors

- Significant interaction between condition and congruency (F(2,33)= 15.81, p< .001)

A new paradigm

146ms***

A new paradigm

• Does it work?

- Yes!

- Next step: examine the effect of top-

- Next step: examine the effect of top-down manipulations on the conscious VS unconscious trials

General conclusions

• Unconscious information

- Can influence our behavior

- Has limited bottom-up strength, but is

- Has limited bottom-up strength, but is still able to be processed up to a high, semantic level

- Seems to be able to exert top-downcontrol as well, although further research using an improved paradigm is needed

Contact

Eva Van den Bussche

Vrije Universiteit Brussel

Department of Psychology

Pleinlaan 2

1050 Brussels

Belgium

Eva.Van.den.Bussche@vub.ac.be

http://homepages.vub.ac.be/~evdbussc//

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