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

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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