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 during stimulus identification (e.g., Stroop task) Resolution of conflict changes how operations are executed in the future

Overview

Sources of Conflict Conflict between dimensions of bivalent stimuli Stroop interference – dominant dimension as source of conflict Special case of basic conflict between competing candidates during stimulus identification GREEN

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 color concept inhibits word pathway

Item Specificity Theme of models: attentional selection or blocking of processing route – general effects Contrasts with cases of item specificity Allport & Wylie (2000) – larger switch cost for naming color words that also appeared on color naming trials

Process Modulation Basic proposition: Resolving conflict has a long-term consequence for how a process is executed responding to nondominant dimension (color naming) alters processing of dominant dimension (word reading) Item specific vs. general effect Color-word Stroop task report color dimension, consequences for word reading

General Paradigm Predictable and spatially cued alternation between color naming and word reading

General Paradigm Runs of 10 trials for each condition Expect Stroop effect on color naming Primary interest in word reading latency

General Paradigm ***** gram ***** hire gram pace hire void tide pace void

General Paradigm Primary interest in word reading latency track latency across trials within a block neutral vs. interference

Process Modulation

Test for Specificity 300 nonrepeated words vs. 5 repeated words n = 200 n = 100

Test for Specificity

Process Modulation Modulation of simple task of word reading No initial evidence for item specificity Rapid instantiation and disengagement Effects of task switching areremoved 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 in interference block

Further Test of Specificity Color naming Word reading Color naming Word reading

Further Test of Specificity

Item specificity

Further Test of Specificity Item specificity and modulation are dissociated

Specificity in Process Modulation Item-specific mechanism ruled out as the source of modulation of word reading Modulation could be a general effect of selective attention or a consequence of backward 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

Specificity in Process Modulation

Cohort specificity constrains modulation

Specificity in Process Modulation Generalization beyond cohort – transfer of modulation across cohort boundaries Cohort boundaries may be defined by particular dimensions modulation of items sharing features with color naming cohort but features on what dimension(s)? phonological (orthographic) semantic

Specificity in Process Modulation Phonological relationship across cohorts Item pool Related Unrelated condition condition barnbark lunchlung printprince sharksharp workword crustcrush darkdart formfork marchmarsh turnturf

Specificity in Process Modulation

Semantic relationship across cohorts Item pool Related Unrelated condition condition boatship jailprison beerale coatjacket rockstone enginemotor pailbucket studentpupil pennycent creekstream

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

Specificity in Process Modulation Cohort learning across blocks of trials

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