verbal working memory and speech errors eleanor drake 15 th february 2008

Verbal working memory Verbal working memory and speech errorsand speech errors

Eleanor DrakeEleanor Drake

1515thth February 2008 February 2008

OutlineOutline

• IntroductionIntroduction• Working memoryWorking memory

– Phonological loopPhonological loop– Measuring functionMeasuring function

• Short-term memory and speech errorsShort-term memory and speech errors• Saito and Baddeley (2004) exp. 1Saito and Baddeley (2004) exp. 1• Current studyCurrent study

– AimAim– Speech taskSpeech task

• Results and interpretationResults and interpretation– Correlatory findingsCorrelatory findings

• Results and interpretationResults and interpretation

IntroductionIntroduction

• Saito and Baddeley (2004) report Saito and Baddeley (2004) report correlation between vSTM correlation between vSTM performance and speech error rate.performance and speech error rate.

• Current study aim = determine if Current study aim = determine if correlation replicable using different correlation replicable using different error-elicitation paradigm. error-elicitation paradigm.

Working MemoryWorking Memory

• Responsible for temporary storage and Responsible for temporary storage and processing of information.processing of information.

• Baddeley and Hitch (1974) model has been Baddeley and Hitch (1974) model has been highly influential.highly influential.

• Proposed a system involving a central Proposed a system involving a central executive + subservient modality specific executive + subservient modality specific visuo-spatial sketch pad and phonological loop visuo-spatial sketch pad and phonological loop (and an episodic buffer, in later versions).(and an episodic buffer, in later versions).

• Phonolgical loop function focus of current Phonolgical loop function focus of current study.study.

Working memory modelWorking memory model

Phonological loopPhonological loop

• Responsible for short-term storage, and checking Responsible for short-term storage, and checking of verbal materialof verbal material

• Bi-componential:Bi-componential:– Phonological store:Phonological store:

• storage of phonologically encoded informationstorage of phonologically encoded information• information subject to decay (c. 1.5-2s)information subject to decay (c. 1.5-2s)

– Subvocal articulatory rehearsalSubvocal articulatory rehearsal• Cycles phonologically encoded information to refresh Cycles phonologically encoded information to refresh

storestore• Recoding non-phonological (i.e., printed word) into Recoding non-phonological (i.e., printed word) into

phonological formphonological form• Evidence- “word-length effect”, “articulatory Evidence- “word-length effect”, “articulatory

suppression”suppression”

Measures of phonological loop Measures of phonological loop function function

•Forward serial recallForward serial recall– (e.g., Wechsler 2003 digit span)(e.g., Wechsler 2003 digit span)– Taken to relate to rate of articulatory Taken to relate to rate of articulatory

rehearsal (i.e., individuals with a higher rehearsal (i.e., individuals with a higher score rehearse more rapidly)score rehearse more rapidly)

– Repetition or matchingRepetition or matching– Measures Measures verbalverbal short-term memory short-term memory

Measures of phonological loop Measures of phonological loop functionfunction

• Nonword repetitionNonword repetition– Repetition of phonotactically acceptable but Repetition of phonotactically acceptable but

lexically empty syllable stringslexically empty syllable strings– Minimize contribution of long-term Minimize contribution of long-term

phonological, lexical, and semantic knowledge phonological, lexical, and semantic knowledge (Gathercole & Baddeley, 2003)(Gathercole & Baddeley, 2003)

– Greater reliance on auditory discrimination, Greater reliance on auditory discrimination, motor planning and execution (Edwards and motor planning and execution (Edwards and Lahey, 1998)Lahey, 1998)

– Measures Measures phonologicalphonological short-term memory short-term memory

STM and speech production STM and speech production errorserrors

• Why might there be a correlation?Why might there be a correlation?– Qualitatively similar errors = common locus in Qualitatively similar errors = common locus in

information processing? information processing? • E.g., Ellis, 1980; Page et al, 2007E.g., Ellis, 1980; Page et al, 2007• Similarity can be simulated via computational Similarity can be simulated via computational

modelling (Page and Norris, 1998a) modelling (Page and Norris, 1998a)

– ““Serial-ordering mechanism” malfunction as Serial-ordering mechanism” malfunction as origin of normal speech errors origin of normal speech errors • E.g, Nespoulos et al. 1984E.g, Nespoulos et al. 1984

– vSTM lower in PWS vSTM lower in PWS • (Bosshardt 1990; Bosshardt 1993)(Bosshardt 1990; Bosshardt 1993)

Saito and Baddeley (2004)Saito and Baddeley (2004)

• Experiment 1Experiment 1– Does elicited speech error rate relate to Does elicited speech error rate relate to

phonological loop function?phonological loop function?•Measured PL function via serial digit recall Measured PL function via serial digit recall

– Auditory distractor technique as error-Auditory distractor technique as error-elicitation paradigmelicitation paradigm•Target word (e.g., “shizuoka”) produced in Target word (e.g., “shizuoka”) produced in

response to tone.response to tone.•Cue tone replaced 1/10 by similar distractor Cue tone replaced 1/10 by similar distractor

word (e.g., “shiozuke”), 1/10 by dissimilar word (e.g., “shiozuke”), 1/10 by dissimilar distractor distractor


• FindingsFindings– Error rate = .031/ .291 (dissimilar/ similar condition)Error rate = .031/ .291 (dissimilar/ similar condition)

– Speech error rate correlated with digit span task Speech error rate correlated with digit span task performance; r = - 0.33, p < .05.performance; r = - 0.33, p < .05.

• InterpretationInterpretation– Both vSTM and speech task performance share Both vSTM and speech task performance share

predication on a “phonological planning factor”predication on a “phonological planning factor”

Current studyCurrent study

• Does the correlation hold for: Does the correlation hold for:

– another error-elicitation paradigm?another error-elicitation paradigm?•Uses Wilshire’s (1999) tongue-twister taskUses Wilshire’s (1999) tongue-twister task

– different tests of auditory short-term different tests of auditory short-term memory?memory?•Uses serial digit recall, serial digit matching, Uses serial digit recall, serial digit matching,

and NWRand NWR

Speech errorsSpeech errors

• Task involves reading monosyllabic Task involves reading monosyllabic wordswords

• Errors (i.e., deviations from the speech Errors (i.e., deviations from the speech plan) assumed to occur at level ofplan) assumed to occur at level of– FormulationFormulation

• Phonological encodingPhonological encoding

– ArticulationArticulation•Execution fault in control of muscular processes Execution fault in control of muscular processes

– Not conceptualisationNot conceptualisation

Speech error elicitationSpeech error elicitation

• Wilshire (1999)Wilshire (1999)• 64 “tongue-twisters”64 “tongue-twisters”

– 4 monosyllabic words on screen, sequence 4 monosyllabic words on screen, sequence to be repeated 4 times, at rate of 100 wpmto be repeated 4 times, at rate of 100 wpm

– 32 control, 16 ABBA onset, 16 ABAB onset32 control, 16 ABBA onset, 16 ABAB onset– Of 32 non-control items 16 alliterating Of 32 non-control items 16 alliterating

similar, 16 alliterating dissimilar (near even similar, 16 alliterating dissimilar (near even distribution)distribution)

– Egs.- Egs.-

Quadruple examplesQuadruple examples

• ControlControl- CUB TIME DATE SIN - CUB TIME DATE SIN • ABBA dissimilarABBA dissimilar - BED COUGH CARD - BED COUGH CARD

BEEF BEEF • ABBA similarABBA similar - DIRT BUS BOOT - DIRT BUS BOOT

DOSEDOSE• ABAB dissimilarABAB dissimilar - TIN MAP TYPE - TIN MAP TYPE

MOON MOON • ABAB similarABAB similar - SAP TIFF SURF TOP - SAP TIFF SURF TOP

Other parametersOther parameters

• Serial digit recall repetitionSerial digit recall repetition

• Serial digit recall matchingSerial digit recall matching

• Nonword repetitionNonword repetition

• Digit articulation timeDigit articulation time

• N =15N =15

Tongue-twister resultsTongue-twister results

• Error-rate:- 16.7% quadruples errorfulError-rate:- 16.7% quadruples errorful

• Error-rate by individual words within Error-rate by individual words within quad:-quad:-– Overall = 1.5% Overall = 1.5% – Control = .71%Control = .71%– ABBA dissimilar = .63%ABBA dissimilar = .63%– ABAB dissimilar = 1.77%ABAB dissimilar = 1.77%– ABBA similar = 1.77%ABBA similar = 1.77%– ABAB similar = 4.13%ABAB similar = 4.13%


• Analysis of varianceAnalysis of variance– A/S significantly more error prone thanA/S significantly more error prone than

•Control (t = 3.66, p < .005)Control (t = 3.66, p < .005)•A/D (t = 3.51, p < .005)A/D (t = 3.51, p < .005)•(control v A/D; no significant difference)(control v A/D; no significant difference)

– ABAB significantly more error prone thanABAB significantly more error prone than•Control (t = 4.138, p < .005)Control (t = 4.138, p < .005)•ABBA (t = 3.032, p < .05)ABBA (t = 3.032, p < .05)•(control v ABBA; no significant difference) (control v ABBA; no significant difference)


• Word position:Word position:– Word 3 (e.g., sap tiff Word 3 (e.g., sap tiff surf surf top) significantly more error top) significantly more error

prone (for ABAB sub-set)prone (for ABAB sub-set)Percentage of syllables produced incorrectly by quad type and position within quad

0

1

2

3

4

5

6

7

8

9

10

control ABBA dissimilar ABAB dissimilar ABBA similar ABAB similar

Quad type

per

cen

tag

e o

f sy

llab

les

pro

du

ced

in

corr

ectl

y

words1

Word 2

Word 3

Word 4


• ReiterationReiteration

– 11stst recitation less error prone recitation less error prone•2 v 1: t = 2.68 2 v 1: t = 2.68 •3 v 1: t = 2.48 3 v 1: t = 2.48 pp < .05 all cases < .05 all cases•4 v 1: t = 2.634 v 1: t = 2.63

– No significant differences amongst other No significant differences amongst other recitation numbers.recitation numbers.

Tongue-twister results Tongue-twister results

• SummarySummary

– Error rate higher whenError rate higher when•ABAB … and/ orABAB … and/ or•A/SA/S•Word position 3Word position 3

– Error rate significantly lowerError rate significantly lower•11stst recitation recitation

Discussion speech taskDiscussion speech task

• Speech error rate (1.5%) Speech error rate (1.5%) – Wilshire (4.5%)Wilshire (4.5%)

•Heterogeneity of participants, experimental Heterogeneity of participants, experimental conditions, error-sensitivity of scorerconditions, error-sensitivity of scorer

– Saito and Baddeley (29.6%)Saito and Baddeley (29.6%)• In error-eliciting conditionsIn error-eliciting conditions

– Spontaneous speech (0.1-0.2%) Spontaneous speech (0.1-0.2%) (Garnham et al. (Garnham et al.

1981)1981) •Suggests paradigm does elicit errorsSuggests paradigm does elicit errors


• A/S > A/D:- phonological similarity A/S > A/D:- phonological similarity effecteffect– Conforms with Wilshire (1999)Conforms with Wilshire (1999)– Cf. PSE in serial recallCf. PSE in serial recall

• ABAB > ABBA:-ABAB > ABBA:-– Contrary to Wilshire (1999)Contrary to Wilshire (1999)– Contrary to Sevald and Dell (1994)Contrary to Sevald and Dell (1994)– Design flaw? Design flaw? – Requires control experimentRequires control experiment


• Word 1 > words 2/ 3/ 4Word 1 > words 2/ 3/ 4– In ABAB subsetIn ABAB subset– Point at which A and B onsets are Point at which A and B onsets are

equiprobableequiprobable– Experimental design -> preference for Experimental design -> preference for

ABBA?ABBA?

Discussion speech tasksDiscussion speech tasks

• Recitation 1 < recitation 2/ 3/ 4Recitation 1 < recitation 2/ 3/ 4– Consistent with Wilshire (1999)Consistent with Wilshire (1999)

• She proposes explanationsShe proposes explanations

• Phonological planning fatigue?Phonological planning fatigue?

• Strategies by which plan re-used?Strategies by which plan re-used?

• Interference/ decay (cf. WM model)Interference/ decay (cf. WM model)

– Another suggestionAnother suggestion• Overt articulation having occurred impacts on Overt articulation having occurred impacts on

psychological/ physiological representations of the psychological/ physiological representations of the phrasephrase


• How?How?– Feedback from production creating Feedback from production creating

interefernceinterefernce– Overt articulation (opposed to Overt articulation (opposed to

articulatory rehearsal) ->articulatory rehearsal) ->•Proprioceptive or sensorimotor feedbackProprioceptive or sensorimotor feedback

•Auditory feedbackAuditory feedback


• Proprioceptive/ sensorimotorProprioceptive/ sensorimotor– Suggested in stuttering literature (e.g., Suggested in stuttering literature (e.g.,

Max et al. 2004)Max et al. 2004)– A/S more error-prone because of gestural A/S more error-prone because of gestural

similarity (cf. Articulatory Phonology)similarity (cf. Articulatory Phonology)– PSE becomes apparent with overt PSE becomes apparent with overt

articulation (Oppenheim and Dell, 2007)articulation (Oppenheim and Dell, 2007)– Non-canonical errors Non-canonical errors


• Auditory feedbackAuditory feedback– Gestural adjustment to correct perceived Gestural adjustment to correct perceived

speech errorspeech error– Conventional PSE from participant’s self-Conventional PSE from participant’s self-

generated auditory inputgenerated auditory input– Cf. effect of similar auditory distractor in Cf. effect of similar auditory distractor in

Saito and Baddeley studySaito and Baddeley study– Cf. stuttering literature on error-inducing Cf. stuttering literature on error-inducing

properties of own speech (Stuart et al., properties of own speech (Stuart et al., 1996) 1996)

Correlatory resultsCorrelatory results

• Descriptive stats and correlation matrix Descriptive stats and correlation matrix attachedattached

• Tongue-twister results correlate withTongue-twister results correlate with– Serial repetition (r = -.527)Serial repetition (r = -.527)– Serial matching (r = -.673)Serial matching (r = -.673)

• Serial recall results also correlate withSerial recall results also correlate with– Digit articulation time (r = -.671)Digit articulation time (r = -.671)– Age (r = -.570)Age (r = -.570)

• NWR no significant correlationsNWR no significant correlations

Correlations discussionCorrelations discussion

• Serial digit repetition and matchingSerial digit repetition and matching– Correlation suggests shared underlying factor(s)Correlation suggests shared underlying factor(s)– Phonological planning ?Phonological planning ?

• Saito and Baddeley (2004) factor analysisSaito and Baddeley (2004) factor analysis

• Matching doesn’t require digit articulation motor Matching doesn’t require digit articulation motor executionexecution

– Correlation with digit articulation timeCorrelation with digit articulation time• Serial digit recall relates to speed of subvocal Serial digit recall relates to speed of subvocal

articulatory rehearsal articulatory rehearsal

• S & B DAT relates to motor execution because more S & B DAT relates to motor execution because more repetitions?repetitions?


• NWR no correlationNWR no correlation– No inter-rater reliability assessmentNo inter-rater reliability assessment– Individual variation in auditory discriminationIndividual variation in auditory discrimination

•Novel stimulus -> greater reliance on auditory Novel stimulus -> greater reliance on auditory perception and processing abilitiesperception and processing abilities

– Doesn’t tap same processes as vSTM Doesn’t tap same processes as vSTM measuresmeasures•Sounds require novel phonological representationSounds require novel phonological representation


• NWR no correlationNWR no correlation– Contrary to findings of Hulme et al. Contrary to findings of Hulme et al.

(1991)(1991)•Hulme et al. familiarised participants with Hulme et al. familiarised participants with

nonwords before testingnonwords before testing

•So nonwords already had long-term So nonwords already had long-term phonological representation and phonological-phonological representation and phonological-articulatory speech planarticulatory speech plan

•Long-term memory contribution to serial Long-term memory contribution to serial recall tasks (& tongue-twister task?) recall tasks (& tongue-twister task?)


• vWM and speech errorsvWM and speech errors– Higher digit span score associated with fewer Higher digit span score associated with fewer

speech errorsspeech errors– Replicates findings of Saito and Baddeley Replicates findings of Saito and Baddeley

• Different explicit task demands of 2 error-elicitation Different explicit task demands of 2 error-elicitation paradigmsparadigms

– Correlation only exists for tasks involving real Correlation only exists for tasks involving real words words • Items which are already represented within the lexiconItems which are already represented within the lexicon

• PSE in both error-elicitation tasks implicates store?PSE in both error-elicitation tasks implicates store?


• vWM and speech errorsvWM and speech errors– Speech error-rate doesn’t correlate with Speech error-rate doesn’t correlate with

DATDAT•Although DAT involves articulation under Although DAT involves articulation under

pressurepressure•Although DAT indicator of articulatory rehearsal Although DAT indicator of articulatory rehearsal

rate (and hence capacity)rate (and hence capacity)

– Does correlation of speech-error rate and Does correlation of speech-error rate and vWM occur because performance on both vWM occur because performance on both tasks in predicated on robustness of verbal tasks in predicated on robustness of verbal representations ?representations ?

Discussion correlationsDiscussion correlations

• How?How?– Phonological representations vulnerable to Phonological representations vulnerable to

interference at a phonological level (PSE)interference at a phonological level (PSE)– Phonological representations subject to Phonological representations subject to

(limited) interaction from other levels of (limited) interaction from other levels of speech production system (e.g., Rapp & speech production system (e.g., Rapp & Goldrick, 2000)Goldrick, 2000)•Activation can be influenced by lexical Activation can be influenced by lexical

informationinformation•Feedback from an articulatory level Feedback from an articulatory level


• EvidenceEvidence– Wilshire (1998) Wilshire (1998)

•Onset-effect for word but not nonword Onset-effect for word but not nonword tongue-twisters indicates lexical-level tongue-twisters indicates lexical-level contribution contribution

– Tehan and Lalor (2000)Tehan and Lalor (2000)•Serial recall tasks involve lexical accessSerial recall tasks involve lexical access

– Hulme et al. (1991)Hulme et al. (1991)•Serial recall better for newly-learnt words if Serial recall better for newly-learnt words if

participant learns sound + meaningparticipant learns sound + meaning


• Explanation of correlatory pattern?Explanation of correlatory pattern?

– Serial recall correlates with DAT because Serial recall correlates with DAT because both predicated on speed of articulatory both predicated on speed of articulatory rehearsalrehearsal

– Serial recall correlates with error-rate Serial recall correlates with error-rate

because both predicated on strength of because both predicated on strength of phonological representationsphonological representations

verbal working memory and speech errors eleanor drake 15 th february 2008

Documents

phonological store

storerecoding nonphonological

speech errorssaito

serial digit recall

serial digit matching

processing of information

information processing

shortterm storage