Verbal working memory and speech errors Eleanor Drake 15 th February 2008

Outline Introduction Introduction Working memory Working memory –Phonological loop –Measuring function Short-term memory and speech errors Short-term memory and speech errors Saito and Baddeley (2004) exp. 1 Saito and Baddeley (2004) exp. 1 Current study Current study –Aim –Speech task Results and interpretation Results and interpretation –Correlatory findings Results and interpretation Results and interpretation

Introduction Saito and Baddeley (2004) report correlation between vSTM performance and speech error rate. Saito and Baddeley (2004) report correlation between vSTM performance and speech error rate. Current study aim = determine if correlation replicable using different error- elicitation paradigm. Current study aim = determine if correlation replicable using different error- elicitation paradigm.

Working Memory Responsible for temporary storage and processing of information. Responsible for temporary storage and processing of information. Baddeley and Hitch (1974) model has been highly influential. Baddeley and Hitch (1974) model has been highly influential. Proposed a system involving a central executive + subservient modality specific visuo-spatial sketch pad and phonological loop (and an episodic buffer, in later versions). Proposed a system involving a central executive + subservient modality specific visuo-spatial sketch pad and phonological loop (and an episodic buffer, in later versions). Phonolgical loop function focus of current study. Phonolgical loop function focus of current study.

Working memory model

Phonological loop Responsible for short-term storage, and checking of verbal material Responsible for short-term storage, and checking of verbal material Bi-componential: Bi-componential: –Phonological store: storage of phonologically encoded information storage of phonologically encoded information information subject to decay (c s) information subject to decay (c s) –Subvocal articulatory rehearsal Cycles phonologically encoded information to refresh store Cycles phonologically encoded information to refresh store Recoding non-phonological (i.e., printed word) into phonological form Recoding non-phonological (i.e., printed word) into phonological form Evidence- “word-length effect”, “articulatory suppression” Evidence- “word-length effect”, “articulatory suppression”

Measures of phonological loop function Forward serial recall Forward serial recall –(e.g., Wechsler 2003 digit span) –Taken to relate to rate of articulatory rehearsal (i.e., individuals with a higher score rehearse more rapidly) –Repetition or matching –Measures verbal short-term memory

Measures of phonological loop function Nonword repetition Nonword repetition –Repetition of phonotactically acceptable but lexically empty syllable strings –Minimize contribution of long-term phonological, lexical, and semantic knowledge (Gathercole & Baddeley, 2003) –Greater reliance on auditory discrimination, motor planning and execution (Edwards and Lahey, 1998) –Measures phonological short-term memory

STM and speech production errors Why might there be a correlation? Why might there be a correlation? –Qualitatively similar errors = common locus in information processing? E.g., Ellis, 1980; Page et al, 2007 E.g., Ellis, 1980; Page et al, 2007 Similarity can be simulated via computational modelling (Page and Norris, 1998a) Similarity can be simulated via computational modelling (Page and Norris, 1998a) –“Serial-ordering mechanism” malfunction as origin of normal speech errors E.g, Nespoulos et al E.g, Nespoulos et al –vSTM lower in PWS (Bosshardt 1990; Bosshardt 1993) (Bosshardt 1990; Bosshardt 1993)

Saito and Baddeley (2004) Experiment 1 Experiment 1 –Does elicited speech error rate relate to phonological loop function? Measured PL function via serial digit recall Measured PL function via serial digit recall –Auditory distractor technique as error- elicitation paradigm Target word (e.g., “shizuoka”) produced in response to tone. Target word (e.g., “shizuoka”) produced in response to tone. Cue tone replaced 1/10 by similar distractor word (e.g., “shiozuke”), 1/10 by dissimilar distractor Cue tone replaced 1/10 by similar distractor word (e.g., “shiozuke”), 1/10 by dissimilar distractor

Saito and Baddeley (2004)

Findings Findings –Error rate =.031/.291 (dissimilar/ similar condition) –Speech error rate correlated with digit span task performance; r = , p <.05. Interpretation Interpretation –Both vSTM and speech task performance share predication on a “phonological planning factor”

Current study Does the correlation hold for: Does the correlation hold for: –another error-elicitation paradigm? Uses Wilshire’s (1999) tongue-twister task Uses Wilshire’s (1999) tongue-twister task –different tests of auditory short-term memory? Uses serial digit recall, serial digit matching, and NWR Uses serial digit recall, serial digit matching, and NWR

Speech errors Task involves reading monosyllabic words Task involves reading monosyllabic words Errors (i.e., deviations from the speech plan) assumed to occur at level of Errors (i.e., deviations from the speech plan) assumed to occur at level of –Formulation Phonological encoding Phonological encoding –Articulation Execution fault in control of muscular processes Execution fault in control of muscular processes –Not conceptualisation

Speech error elicitation Wilshire (1999) Wilshire (1999) 64 “tongue-twisters” 64 “tongue-twisters” – 4 monosyllabic words on screen, sequence to be repeated 4 times, at rate of 100 wpm –32 control, 16 ABBA onset, 16 ABAB onset –Of 32 non-control items 16 alliterating similar, 16 alliterating dissimilar (near even distribution) –Egs.-

Quadruple examples Control - CUB TIME DATE SIN Control - CUB TIME DATE SIN ABBA dissimilar - BED COUGH CARD BEEF ABBA dissimilar - BED COUGH CARD BEEF ABBA similar - DIRT BUS BOOT DOSE ABBA similar - DIRT BUS BOOT DOSE ABAB dissimilar - TIN MAP TYPE MOON ABAB dissimilar - TIN MAP TYPE MOON ABAB similar - SAP TIFF SURF TOP ABAB similar - SAP TIFF SURF TOP

Other parameters Serial digit recall repetition Serial digit recall repetition Serial digit recall matching Serial digit recall matching Nonword repetition Nonword repetition Digit articulation time Digit articulation time N =15 N =15

Tongue-twister results Error-rate:- 16.7% quadruples errorful Error-rate:- 16.7% quadruples errorful Error-rate by individual words within quad:- Error-rate by individual words within quad:- –Overall = 1.5% –Control =.71% –ABBA dissimilar =.63% –ABAB dissimilar = 1.77% –ABBA similar = 1.77% –ABAB similar = 4.13%

Tongue-twister results Analysis of variance Analysis of variance –A/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 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)

Tongue-twister results Word position: Word position: –Word 3 (e.g., sap tiff surf top) significantly more error prone (for ABAB sub-set) Percentage of syllables produced incorrectly by quad type and position within quad controlABBA dissimilarABAB dissimilarABBA similarABAB similar Quad type percentage of syllables produced incorrectly words1 Word 2 Word 3 Word 4

Tongue-twister results Reiteration Reiteration –1 st recitation less error prone 2 v 1: t = v 1: t = v 1: t = 2.48 p <.05 all cases 3 v 1: t = 2.48 p <.05 all cases 4 v 1: t = v 1: t = 2.63 –No significant differences amongst other recitation numbers.

Tongue-twister results Summary Summary –Error rate higher when ABAB … and/ or ABAB … and/ or A/S A/S Word position 3 Word position 3 –Error rate significantly lower 1 st recitation 1 st recitation

Discussion speech task Speech error rate (1.5%) Speech error rate (1.5%) – Wilshire (4.5%) Heterogeneity of participants, experimental conditions, error-sensitivity of scorer Heterogeneity of participants, experimental conditions, error-sensitivity of scorer – Saito and Baddeley (29.6%) In error-eliciting conditions In error-eliciting conditions –Spontaneous speech ( %) (Garnham et al. 1981) Suggests paradigm does elicit errors Suggests paradigm does elicit errors

Discussion speech task A/S > A/D:- phonological similarity effect A/S > A/D:- phonological similarity effect –Conforms with Wilshire (1999) –Cf. PSE in serial recall ABAB > ABBA:- ABAB > ABBA:- –Contrary to Wilshire (1999) –Contrary to Sevald and Dell (1994) –Design flaw? –Requires control experiment

Discussion speech task Word 1 > words 2/ 3/ 4 Word 1 > words 2/ 3/ 4 –In ABAB subset –Point at which A and B onsets are equiprobable –Experimental design -> preference for ABBA?

Discussion speech tasks Recitation 1 < recitation 2/ 3/ 4 Recitation 1 < recitation 2/ 3/ 4 –Consistent with Wilshire (1999) She proposes explanations She 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 suggestion Overt articulation having occurred impacts on psychological/ physiological representations of the phrase Overt articulation having occurred impacts on psychological/ physiological representations of the phrase

Discussion speech tasks How? How? –Feedback from production creating interefernce –Overt articulation (opposed to articulatory rehearsal) -> Proprioceptive or sensorimotor feedback Proprioceptive or sensorimotor feedback Auditory feedback Auditory feedback

Discussion speech tasks Proprioceptive/ sensorimotor Proprioceptive/ sensorimotor –Suggested in stuttering literature (e.g., Max et al. 2004) –A/S more error-prone because of gestural similarity (cf. Articulatory Phonology) –PSE becomes apparent with overt articulation (Oppenheim and Dell, 2007) –Non-canonical errors

Discussion speech tasks Auditory feedback Auditory feedback –Gestural adjustment to correct perceived speech error –Conventional PSE from participant’s self- generated auditory input –Cf. effect of similar auditory distractor in Saito and Baddeley study –Cf. stuttering literature on error-inducing properties of own speech (Stuart et al., 1996)

Correlatory results Descriptive stats and correlation matrix attached Descriptive stats and correlation matrix attached Tongue-twister results correlate with Tongue-twister results correlate with –Serial repetition (r = -.527) –Serial matching (r = -.673) Serial recall results also correlate with Serial recall results also correlate with –Digit articulation time (r = -.671) –Age (r = -.570) NWR no significant correlations NWR no significant correlations

Correlations discussion Serial digit repetition and matching Serial digit repetition and matching –Correlation suggests shared underlying factor(s) –Phonological planning ? Saito and Baddeley (2004) factor analysis Saito and Baddeley (2004) factor analysis Matching doesn’t require digit articulation motor execution Matching doesn’t require digit articulation motor execution –Correlation with digit articulation time Serial digit recall relates to speed of subvocal articulatory rehearsal Serial digit recall relates to speed of subvocal articulatory rehearsal S & B DAT relates to motor execution because more repetitions? S & B DAT relates to motor execution because more repetitions?

Correlations discussion NWR no correlation NWR no correlation –No inter-rater reliability assessment –Individual variation in auditory discrimination Novel stimulus -> greater reliance on auditory perception and processing abilities Novel stimulus -> greater reliance on auditory perception and processing abilities –Doesn’t tap same processes as vSTM measures Sounds require novel phonological representation Sounds require novel phonological representation

Correlations discussion NWR no correlation NWR no correlation –Contrary to findings of Hulme et al. (1991) Hulme et al. familiarised participants with nonwords before testing Hulme et al. familiarised participants with nonwords before testing So nonwords already had long-term phonological representation and phonological-articulatory speech plan So nonwords already had long-term phonological representation and phonological-articulatory speech plan Long-term memory contribution to serial recall tasks (& tongue-twister task?) Long-term memory contribution to serial recall tasks (& tongue-twister task?)

Correlations discussion vWM and speech errors vWM and speech errors –Higher digit span score associated with fewer speech errors –Replicates findings of Saito and Baddeley Different explicit task demands of 2 error-elicitation paradigms Different explicit task demands of 2 error-elicitation paradigms –Correlation only exists for tasks involving real words Items which are already represented within the lexicon Items which are already represented within the lexicon PSE in both error-elicitation tasks implicates store? PSE in both error-elicitation tasks implicates store?

Correlations discussion vWM and speech errors vWM and speech errors –Speech error-rate doesn’t correlate with DAT Although DAT involves articulation under pressure Although DAT involves articulation under pressure Although DAT indicator of articulatory rehearsal rate (and hence capacity) Although DAT indicator of articulatory rehearsal rate (and hence capacity) –Does correlation of speech-error rate and vWM occur because performance on both tasks in predicated on robustness of verbal representations ?

Discussion correlations How? How? –Phonological representations vulnerable to interference at a phonological level (PSE) –Phonological representations subject to (limited) interaction from other levels of speech production system (e.g., Rapp & Goldrick, 2000) Activation can be influenced by lexical information Activation can be influenced by lexical information Feedback from an articulatory level Feedback from an articulatory level

Discussion correlations Evidence Evidence –Wilshire (1998) Onset-effect for word but not nonword tongue- twisters indicates lexical-level contribution Onset-effect for word but not nonword tongue- twisters indicates lexical-level contribution –Tehan and Lalor (2000) Serial recall tasks involve lexical access Serial recall tasks involve lexical access –Hulme et al. (1991) Serial recall better for newly-learnt words if participant learns sound + meaning Serial recall better for newly-learnt words if participant learns sound + meaning

Discussion correlations Explanation of correlatory pattern? Explanation of correlatory pattern? –Serial recall correlates with DAT because both predicated on speed of articulatory rehearsal –Serial recall correlates with error-rate because both predicated on strength of phonological representations