Proceedings Fonetik 2009 - Institutionen för lingvistik

More documents

Recommendations

Info

Proceedings, FOETIK 2009, Dept. of Linguistics, Stockholm UniversityLanguage-specific speech perception as mismatchnegativity in 10-month-olds’ ERP dataIris-Corinna Schwarz 1 , Malin Forsén 2 , Linnea Johansson 2 , Catarina Lång 2 , Anna Narel 2 , TanyaValdés 2 , and Francisco Lacerda 11 Department of Linguistics, Stockholm University2 Department of Clinical Science, Intervention, and Technology, Speech Pathology Division,Karolinska Institutet, StockholmAbstractDiscrimination of native and nonnative speechcontrasts, the heart of the concept of languagespecificspeech perception, is sensitive to developmentalchange in speech perception duringinfancy. Using the mismatch negativityparadigm, seven Swedish language environment10-month-olds were tested on their perceptionof six different consonantal and tonalThai speech contrasts, native and nonnative tothe infants. Infant brain activation in responseto the speech contrasts was measured withevent-related potentials (ERPs). They showmismatch negativity at 300 ms, significant forcontrast change in the native condition, but notfor contrast change in the nonnative condition.Differences in native and nonnative speech discriminationare clearly reflected in the ERPsand confirm earlier findings obtained by behaviouraltechniques. ERP measurement thussuitably complements infant speech discriminationresearch.IntroductionSpeech perception bootstraps language acquisitionand forms the basis for later language development.During the first six months of life,infants are ‘citizens of the world’ (Kuhl, 2004)and perform well in both nonnative and nativespeech discrimination tasks (Burnham, Tyler, &Horlyck, 2002).For example, 6-month-old English andGerman infants tested on a German, but notEnglish contrast [dut]-[dyt], and an English, butnot German contrast [dɛt]-[dæt], discriminatedboth contrasts equally well (Polka & Bohn,1996). Around the age of six months, a perceptualshift occurs in favour of the native language,earlier for vowels than for consonants(Polka & Werker, 1994). Around that time infants’nonnative speech discrimination performancestarts to decline (Werker & Lalonde,1988), while they continue to build their nativelanguage skills (Kuhl, Williams, Lacerda, Stevens,& Lindblom, 1992). For example, 10- to12-month-old Canadian English environmentinfants could neither discriminate the nonnativeHindi contrast [ʈɑ]-[tɑ] nor the nonnativeThompson 1 contrast [ki]-[qi] whereas their 6- to8-month-old counterparts still could (Werker &Tees, 1984).This specialisation in the native languageholds around six months of age even on a supra-segmentallanguage level: American Englishlanguage environment infants younger thansix months are equally sensitive to all stresspatterns of words, and do not only prefer theones predominantly present in their native languageas infants older than six months do(Jusczyk, Cutler, & Redanz, 1993).During the first year of life, infants’ speechperception changes from language-general tolanguage-specific in several features. Adults arealready so specialised in their native languagethat their ability to discriminate nonnativespeech contrasts is greatly diminished and canonly partially be retrained (Tees & Werker,1984; Werker & Tees, 1999, 2002). By contrastingnative and nonnative discriminationperformance the degree of language-specificityin speech perception is shown and developmentalchange can be described (Burnham, 2003).In the presence of experience with the nativelanguage, language-specific speech perceptionrefines, whereas in the absence of experiencenonnative speech perception declines. Thisstudy focuses on 10-month-olds whose speechperception is language-specific.A common behavioural paradigm used totest discrimination abilities in infants youngerthan one year is the conditioned head-turnmethod (e.g., Polka, Colantonio, & Sundara,2001). This method requires the infant to beable to sit on the parent’s lap and to controlhead movement. Prior to the experimental test130
Proceedings, FOETIK 2009, Dept. of Linguistics, Stockholm Universityphase, a training phase needs to be incorporatedinto the experiment to build up the associationbetween perceived changes in contrast presentationand reward display in the infants. Thenumber of trials that it takes the infant to reachcriterion during training significantly reducesthe possible number of later test trials since thetotal test time of 10 min maximum remains invariantin infants.Can electroencephalography (EEG) measurementprovide a physiological correlate to thebehavioural discrimination results? The answeris yes. Brain activation waves in response tostimulus presentation are called event-relatedpotentials (ERPs) and often show a stimulustypicalcurve (Teplan, 2002). This can be forexample a negativity response in the ERP,called mismatch negativity (MMN), reflectingstimulus change in a series of auditory signals(Näätänen, 2000). MMN reflects automaticchange detection processes on neural level(Kushnerenko, Ceponiene, Balan, Fellman, &Näätänen, 2002). It is also used in neonate testingas it is the earliest cognitive ERP componentmeasurable (Näätänen, 2000). The generaladvantage of using ERPs in infant research liesexactly within in the automaticity of these processesthat does neither demand attention nortraining (Cheour, Leppänen, & Kraus, 2000).For example, mismatch negativity represents6-month-olds’ discrimination of consonantduration changes in Finnish non-sensewords (Leppänen et al., 2002). Similarly, differencesin the stress patterns of familiar wordsare reflected in the ERPs of German and French4-month-olds (Friederici, Friedrich, & Christophe,2007). This reveals early language-specificspeech perception at least in suprasegmentalaspects of language.How infant language development fromlanguage-general to language-specific discriminationof speech contrasts can be mapped ontoneural response patterns was demonstrated in astudy with 7- and 11-month-old American Englishenvironment infants (Rivera-Gaxiola,Silva-Pereya, & Kuhl, 2005). The infants couldbe classed into different ERP patterns groups,showing not only negativity at discriminationbut also positive differences. Discrimination ofSpanish voice-onset time (VOT) differenceswas present in the 7-month-olds but not in the11-month-olds (Rivera-Gaxiola et al., 2005).HypothesisIf ERPs and especially mismatch negativity areconfirmed by the current study as physiologicalcorrelates to behavioural infant speech discriminationdata, 10-month-old Swedish languageenvironment children would discriminatenative, but not nonnative contrast changes, asthey should perceive speech in a languagespecificmanner at this stage of their development.MethodParticipantsSeven 10-month-old infants (four girls andthree boys) participated in the study. Their averageage was ten months and one week, withan age range of ten to eleven months. The participants’contact details were obtained from thegovernmental residence address registry. Familieswith 10-month-old children who live inGreater Stockholm were randomly chosen andinvited to participate via mail. They expressedtheir interest in the study by returning a form onthe basis of which the appointment was bookedover the phone. All children were growing upin a monolingual Swedish-speaking environment.As reward for participation, all familiesreceived certificates with a photo of the infantwearing the EEG net.StimuliSpeech stimuli were in combination with thevowel /a/ the Thai bilabial stops /b̬ /, /b/, and/p h / and the dental/alveolar plosives /d̬ /, /d/, and/t h / in mid-level tone (0), as well as the velarplosive [ka] in low (1), high falling (2), and lowrising (4) tone. Thai distinguishes three voicinglevels. In the example of the bilabial stops thismeans that /b̬ / has a VOT of -97 ms, /b/ of 6 msand /p h / of 64 ms (Burnham, Francis, & Webster,1996). Out of these three stimulus setscontrast pairs were selected that can be contrastive(native) or not contrastive (nonnative) inSwedish. The consonantal contrasts [ba]-[p h a]and [da]-[t h a] are contrastive in Thai and inSwedish, whereas the consonantal contrasts[b̬ a]-[ba] and [d̬ a]-[da] are only contrastive inThai.Both consonantal contrasts were mid-toneexemplars but the third set of contrasts was tonal.It presents the change between high fallingand low rising tone in the contrast [ka2]-[ka4]131
Page 1 and 2:
Department of LinguisticsProceeding
Page 3 and 4:
Proceedings, FONETIK 2009, Dept. of
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Proceedings, FOETIK 2009, Dept. of
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80: Proceedings, FONETIK 2009, Dept. of
Page 127 and 128: Proceedings, FOETIK 2009, Dept. of
Page 129: Proceedings, FOETIK 2009, Dept. of
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227:
Department of LinguisticsPhonetics
show all

Proceedings Fonetik 2009 - Institutionen för lingvistik

Create successful ePaper yourself

Delete template?

Save as template?