In collaboration with Daniel N. Bub
Process Modulation Induced by Stroop Interference
Michael E. J. Masson
University of Victoria
Basic Proposition
• Mental operations may lead to conflict duringstimulus identification (e.g., Stroop task)
• Resolution of conflict changes how operationsare executed in the future
Overview
Conflictbetweenmentaloperations
Theoriesof conflictresolution
The problemof specificity
Evidencefor processmodulationfollowing conflictresolution
Specificityin processmodulation
Sources of Conflict
• Conflict between dimensions of bivalentstimuli
• Stroop interference – dominant dimension assource of conflict
• Special case of basic conflict betweencompeting candidates during stimulusidentification
GREEN COW
TRACK
TRUCK TRUNKTRASH
Theories of Conflict Resolution
• Models of color-word conflict resolution
• Attentional control in a PDP system(Cohen, Dunbar, & McClelland, 1990)
• SLAM (Phaf et al., 1990)
• WEAVER++ (Roelofs, 2003)
• Tectonic theory (Melara & Algom, 2003)
• Attentional selection
• enhances activation of color pathway or colorconcept
• inhibits word pathway
Item Specificity
• Theme of models: attentional selection orblocking of processing route – general effects
• Contrasts with cases of item specificity
• Allport & Wylie (2000) – larger switch cost fornaming color words that also appeared oncolor naming trials
450490530570610650690
1 2 3Trial
Color & WordWord Only
Process Modulation
• Basic proposition: Resolving conflict has along-term consequence for how a process isexecuted
• responding to nondominant dimension (colornaming) alters processing of dominantdimension (word reading)
• Item specific vs. general effect
• Color-word Stroop task• report color dimension, consequences for
word reading
General Paradigm
• Predictable and spatially cued alternationbetween color naming and word reading
=====
Neutral Trial
=====
=====
Interference Trial
=====
=====
=====
=====
=====
*****
tide pace
quest
General Paradigm
• Runs of 10 trials for each condition
• Expect Stroop effect on color naming
• Primary interest in word reading latency
Trial0 10 20 30 40 ...
Interference
Neutral
quest pace
tide*****
/
/
General Paradigm
=======
*****
gram
**********hiregram
pacehirevoidtidepace
void
General Paradigm
• Primary interest in word reading latency
• track latency across trials within a block• neutral vs. interference
Neutral
580
600
620
640
660
680
1 2 3 4 5 6 7 8 9 10
Word Reading
Interference
Trial Within a Block
95% CI
Process Modulationgram
======pace
======
======
*****
======tide
Neutral
580
600
620
640
660
680
1 2 3 4 5 6 7 8 9 10
Word Reading
Interference
Trial Within a Block
95% CI
Process Modulation
======
*****
======tide
gram
======pace
======
Test for Specificity
• 300 nonrepeated words vs. 5 repeated words
noonvotelampdragpace ...
birdtendgramquesttide ...
Colornaming
Wordreading
hirepacetidevoidgram
Colornaming
Wordreading
n = 200
n = 100
Test for Specificity
Nonrepeated Repeated
Words
600
650
700
750
800
Nonrepeated Repeated
Color Naming
NeutralInterference
95% CI
580
600
620
640
660
680
700Word Reading
Test for Specificity
Nonrepeated Repeated
Words
600
650
700
750
800
Nonrepeated Repeated
Color Naming
NeutralInterference
95% CI
580
600
620
640
660
680
700Word Reading
(41 ms)
(37 ms)
Process Modulation
• Modulation of simple task of word reading
• No initial evidence for item specificity
• Rapid instantiation and disengagement
• Effects of task switching are removed
• not a direct result of switch cost
• but may be a component of switch cost
Further Test of Specificity
• Establish item specificity using color words(Allport & Wylie, 2000)
• 5 color words & 5 noncolor words
• only color words appear for color naming ininterference block
Color naming
notice
jobredluck
green march
red
blue blue
Word reading
pinktalk
pink
yellowgreenyellow
Further Test of Specificity
=====
Neutral Trials
=====
=====
Interference Trials
=====
=====
=====
=====
=====blue
job
green
===== =====*****
*****
talk
*****
=====pink
=====
yellow
march
red
pink
Colornaming
Wordreading
Colornaming
Wordreading
Further Test of Specificity
95% CI
600
650
700
750
800
850
Neutral Interference
Color Naming
Block
550
575
600
625
650
Noncolor Color
Word Reading
NeutralInterference
Words
Further Test of Specificity
• Item specificity
95% CI
600
650
700
750
800
850
Neutral Interference
Color Naming
Block
550
575
600
625
650
Noncolor Color
Word Reading
NeutralInterference
Words
95% CI
600
650
700
750
800
850
Neutral Interference
Color Naming
Block
550
575
600
625
650
Noncolor Color
Word Reading
NeutralInterference
Words
Further Test of Specificity
(27 ms)
(25 ms)
• Item specificity and modulation are dissociated
Specificity in Process Modulation
• Item-specific mechanism ruled out as thesource of modulation of word reading
• Modulation could be a general effect ofselective attention or a consequence ofbackward inhibition (Mayr & Keele, 2000)
• Alternative: modulation of a cohort
• but what kind of cohort?
• task-defined cohort
• generalization beyond cohort
Specificity in Process Modulation
• Define word cohorts by task assignment
Task-specific assignment Mixed assignment
gladranchfundpostphone
joinbuzzcampsaveluck
Colornaming
Wordreading
flagmilldampcoattuneflatdeckfatebitelose
Colornaming
Wordreading======
======luck
fund
Neutral Interference
======
buzz
*****
======
Specificity in Process Modulation
95% CI
600
620
640
660
680
Mixed Task Specific
Word Reading
650
700
750
800
850
900
Mixed Task Specific
Color Naming
NeutralInterference
Words
Specificity in Process Modulation
95% CI
600
620
640
660
680
Mixed Task Specific
Word Reading
650
700
750
800
850
900
Mixed Task Specific
Color Naming
NeutralInterference
Words
(16 ms)
(37 ms)
• Cohort specificity constrains modulation
Specificity in Process Modulation
• Generalization beyond cohort – transfer ofmodulation across cohort boundaries
• Cohort boundaries may be defined by particulardimensions
• modulation of items sharing features withcolor naming cohort
• but features on what dimension(s)?• phonological (orthographic)• semantic
Specificity in Process Modulation
• Phonological relationship across cohorts
Item pool Related Unrelated condition conditionbarn barklunch lungprint princeshark sharpwork wordcrust crushdark dartform forkmarch marshturn turf
barnlunchprintsharkwork
barklungprincesharpword
Colornaming
Wordreading
barnlunchprintsharkwork
crustdarkformmarchturn
Colornaming
Wordreading
======
======lung
shark
Neutral Interference
======
word
*****
======
Specificity in Process Modulation
NeutralInterference 95% CI
550
600
650
700
750
Unrelated Related
Color Naming
Item Condition
520
540
560
580
Unrelated Related
Word Naming
Specificity in Process Modulation
NeutralInterference 95% CI
550
600
650
700
750
Unrelated Related
Color Naming
Item Condition
520
540
560
580
Unrelated Related
Word Naming
(16 ms)
(31 ms)
Specificity in Process Modulation
• Semantic relationship across cohorts
Item pool Related Unrelated condition condition
boatjailbeercoatrock
shipprisonalejacketstone
Colornaming
Wordreading
boat ship jail prisonbeer alecoat jacketrock stoneengine motorpail bucketstudent pupilpenny centcreek stream
boatjailbeercoatrock
enginepailstudentpennycreek
Colornaming
Wordreading
Specificity in Process Modulation
550
600
650
700
750
Unrelated Related
Color Naming
NeutralInterference
Item Condition
530
540
550
560
570
580
Unrelated Related
Word Naming
95% CI
(13 ms)
(18 ms)
Specificity in Process Modulation
• Cohort learning across blocks of trials
• prediction about size of modulation effect
• common cohort• consistent modulation across blocks
• distinct cohort• modulation initially large but reduced
across blocks
Specificity in Process Modulation
• Cohort learning across blocks of trials
560
580
600
620
640
660
680
1 2 3 4 5 6 7 8 9 10
Common Cohort
InterferenceNeutral
Block
500
520
540
560
580
600
620
1 2 3 4 5 6 7 8
Distinct Cohort
Block
95% CI
32 ms
31 ms
Specificity in Process Modulation
• Cohort learning across blocks of trials
560
580
600
620
640
660
680
1 2 3 4 5 6 7 8 9 10
Common Cohort
InterferenceNeutral
Block
500
520
540
560
580
600
620
1 2 3 4 5 6 7 8
Distinct Cohort
Block
95% CI
32 ms
31 ms
36 ms
16 ms
Conclusions
• Modulation of conflicting task (word reading)
• component of task-switch cost
• Rapid engagement and disengagement
• Learned cohort specificity, not item specificity
• phonological cohorts
• Implications for other forms of interference
• picture-word Stroop, numeric Stroop
• basic object and word identification processes
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