Iil Joumal of Speecharl Hearing Research,Volune 36, l25f-l}70, December L993 3- -E '- Auerucex Speecn-uexclJAcE' First .La nguage Acquisition After HEARNO Assocmon Childhood Differs From Second, Acquisition: The Case of American Sign Language

Rachel I. Mayberry McGill Universirl Mutreal, Canada

This study determined whetherthe long-rangeoutcome of first-language acquisition,when the learningUegins after earty childhood,is similarto that of second-language.acquisition. Subiects were 86 deaf adults who had contrasting histories of spoken and sign tanguale acquisition. (ASL) Twenty-seven subjects were born deaf and began to acquire American Sign language as a first ianguage at ages ranging from infancy to late childhood. Nine other subjects were born with normlt nlaring,-which ihet bst in late childhood; they subsequently acquired ASL as a in early second language (b"ou"" they had acquired spoken English as a childhood). lSL sentence processing was measured by recall of long and complex sentences after and short-term memory for signed digits. Subjectswho acquired ASL as a second language age. In childhood outperformed those who acquired it as a first language at exactly the same in addition, the performance of the subjects who acquired ASL as a first language declined association with increasing age of acquisition. Efiects were most apparent for sentence processing skills related to lexical identification, grammatical acceptability, and memory for pattern sentence meaning. No efiects were found for skills related to fine-motor production and segmentation. (ASL)' Kff WORDS: acqulslilon, crltlcal period, deafness, Amerlcan Sign language second-language acquisltlon

Early in life children spontaneouslyacquire language, barring exceptionalcircum- are stances. For most peopie, then, any languagesthey learn after early childhood a first second tanguages-languages acquiredover and above the prior acquisitionof of language. For children-who are born severely or profoundly deaf, the timing hearing first-language acquisition can be radically off-schedule. Unlike normally eallY children, many deaf children have only limited access to language during the childhood in either spoken or signed foims (Mayberry, 1992)' This means that of acquisitionof sign language by iome (but not all) deaf individualsis an example first-languageacquisition begun atypicallylate. The unusualcircumstancei of sign languageacquisition compels us to ask whether same the long-range outcome of tanguageacquisition begun after childhood is the regardlEss Jf *h"tn"r it is a case of first- as compared to second-language and acluisition. The present studywas designedto answerthis question.The context moiivationfor this study are rootedin previousresearch in spoken and sign language acquisitionand processing,as will shortly become clear. idea The notionthat childrenare betterat languageacquisition than adults is an old (e.9.' that underlies much early childhoodtanguage education and intervention see penfield, 1g5g). Tlre "criiicat period hypothesisfor tanguageacquisition" specifically proposesthat ihe outcome of ianguageacquisition is not uniformover the lifespanbut

1258 0022-4685193/3606-I 258S0 I .00/0 @ 1993, American Speech-Language'Hearing Associacion

-t M.yb"rry: First-Iznguge AcquisitionAfrcr Ctildhnd 12Sg

ratheris optimalwhenit occursduring childhood (Lenneberg, parentswhose primarylanguage was sign, eitherASL or 1964. Althoughthe criticalperiod hypothesis for language PSE).The other half of thesubjects were non-native tearners acquisitionis widelyheld to be true(snow, 1994, it has been of ASL (that is, deaf adults who were raisedin families very difficultto test (columbo,1gg2). one mainproblem is headedby normailyhearing parents whose primaryran- thatthe circumstancesthat preventlanguage acquisition in guagewas spokenEngrish and who usedritfle or no earlylife are oftenso devastatingto tnethitd's development sign). The subjectsshadowed ASL and psE narrativesand thatthe dataare confounded(curtiss, 1927; skuse, lggg). an- swered comprehensionquestions aftenrard. Two normallyoccurring circumstances of post-childhood The native learnerssignificantty outperformed the non-native languageacquisition have been available for siudy,however. learners on the narrative-shadowingtasks and the one is second-languageacquisition, which has been studied comprehension- questiontasks (in both ASL and psE). extensively.Theother is signlanguage acquisition, the study In addiiion,perfor- of whichis morerecent. mance on the two tasks was significanflyand positively correlated.Thus, performance accuracy The long+angeoutcome of second-languageacquisition is on processingtaski givenin signlanguage reflect predictedin large_partby the age at whichthJleaming occurs the degreeto whichthe subject comprehendedthe (scovel,1g8g). Given equal practice and training,indMduals stimuli. In bothstudies, performance whobegin to leama secondlanguage during childhood or.fiper- accuracywas further related to the linguisticnature formtheir peers who begin to learnit afterchildhood on uiuty of the lexicalsubstitutions the subjects made while performing of languageme€Fures (ltashen, Long, & Scarcella,1979). " the varioustasks (i.e., sentence The recall, mostsalient efiects of ageof acquisitionare on speechproduc- sentenceshadowing, and narrativeshadowing). The most'common tion.The abilityto pronouncea se@ndlanguage without lexicalmistake was an omission.Less fre- an quent, accent,or likea nativespeaker, declines gradualty throughout butmore revealing, were lexical substitutions wherein the childhoodand precipitousryafterwards (Frege, uiaz; Frege& subjectsaw a particutarstimulus lexical item but re- Fletcher,1992; Oyama, 19Z6). Age of acquisitionhas also been spondedwith anotherone. The lexicalsubstiiutions were primarily foundto afiectperformance on taskssuch as recallof sentence of twolinguistic types, semantic and phonological. meaning(oyarna 1g7g),paraphrase and synta\ skills(coppi- semantic lexical substitutionsmaintained the intended eters,1984, andgrammaticaljudgments (Johnson & ttewport, meaningof the stimulussentence and wereconsistent with 1989,1991). thesemantic domain and syntactic role of thestimulus lexical The efiectsof age of acquisitionon the rong-rangeout- item.For example,one stimulusASL sentence(translated come of languageacguisition are not limiteJ to iporen into English)was, "As a chirdI arwaysprayed with my otder languages but atso appear.in sign languages.Newport brother."some subjectsrepeatedlthe itimulus with the (1988' 1990)found agg of acquisitionto preoiathe accurary followinglexicalsubstitution: "As a childlalways played with with whictrhighly practiced deaf signerscould comprehend my younger brother." This semantic lexical substitution and produce the_complexmorphology of AmericanSign $toungervs. oldef showsthat the subjectbasically under- Language(ASL). Emmoreyand corina 1rsso1found age-ot stood the stimulussentence, even thoughhis oi her re- acquisitionto predictthe speedwith which deaisigners could sponsewas not a verbatimrendition. Thus, semantic substi- recognize ASL signs (i.e.,words). In a seriesof studies, tutions were positivety correlated with both processing Mayberryand hercolleagues(Mayberry, 1993; Mayberry & accuracyand comprehension-questionperformance (May- Eichen,1991; Mayberry & Fischer,lggg) havefound numer- berry& Fischer,1gg9). ous efiectsof age of acquisition on sign languageprocess- Phonologicallexical substitutions showed a differentlin- ing.The presentstudy is an extension of thJseiindingr, ro guisticrelationship to the stimuluslexical item, one tied to theyare summarizedhere in detail. surfacepattern structure but divorcedfrom lexical or senten- In the first study,Mayberry and Fischer(19g9) foundprior tial meaning.For example,one stimulusASL sentence experiencewifr ASL (measuredin yearsof predict usage)to (translatedinto Engtish)was, "l ate too much turkeyand the performanceof 5s deaf college studentson-t*o kindsof potatoat Thanksgivingdinner." one subjectchanged sentence-processingtasks, immediate ,,steep', the recalland shadowing sign "anC" to the sign producingthe (simultaneousreception and production re--sponse of sentencestimulfi translatedas, "l ate too much turkey sleep potato." of sign languageexperience afiected performance The !"ngth on lexicalsubstitution bears no semanticrelationship to either nro.gss.ingtasks in a rinearfashion: the rongerthe Pof signer the stimulussentence or the target lexicalitem (s/eepvs. had used sign language(from 2 to 2O years), the more anq.However,there is a strikingphonotogical reiationship accuratelyhe or shecould recall and shadowASL sentences. betweenthe two signs, as Figure 1 shows.The lexical ln a secondstudy, Mayberry and Fischer(19g9) measured substitutionvaries from the target in only one articulatory thecomprehension performance of 16 deafcollege students parameter(place of articulation).The two signs rhymein givenin both ASL and pidgin Si'gnEngtish {1pnalives ASL.The phonological substitution suggests that the subject (PSe1.tHalf the subjects were native rearneis otn-sl6nit is, did not fully understandthe sentence,which was borne deaf adultswho were raised in familiesheaded out by deaf by correlationanalyses. phonological lexical substitutions were negativelycorrelated with both processingaccuracy and comprehension-questionperformance (Mlyberry n p!!, Fischer,19s9). The finding :?ls'il::g.lJ1qql, or is a sisndiatect that is structurailysimpter than showedthat these mistikes were wom grder parafiers spoken Engrish and has spars6 grammatical notsimple misarticulations l:r.rfmorphotogy by subjectswho otherwise under- (Witbur,1987; Wooitward, t9i3). stoodthe stimuli. 1260 Jounwlof Speechand' Hearing Reseatch i6 L258-LZ70December 1993

A. SemanticSubstinrtion ence or reflectedinstead age limitationson languageacqui- sition.Subjects were 49 deaf adults who had usedASLfor an average of 42 years but began to acquire it at ages ranging from infancy to 13 years. (Most subjects were not college educated.) The processing task was recall of long and complex ASL sentences.A signed digit-spantask was also administeredto determine whether the subjects' short-term memory spans were comparable. Age of acquisition had significant efiects on several as- pects of the subjects' performance. As age of acquisition fr& increased, the grammatical acceptability of the subiects' responses declined. Likewise, as age of acquisition in- :;:AI _tf t- creased, the similarity in meaning between the subjects' E responses and the stimulus sentences dectined. Age of YOI.'NG OLD acquisitionwas further related to the linguisticnature of the Target Sigr ResponseSign subjects' lexical substitutions. As age of acquisition in- creased, the proportion of lexical substitutionsthat were purely phonologicalincreased while the proportionof lexical substitutions that were purely semantic decreased. The results demonstratedthat age of acquisitionhas significant efiects on the long-rangeoutcome of sign languageacquisi- tion with respectto sentenceprocessing (Maybgrry & Eichen, 1991). Thus, there are clear age limitations on the outcome of sign language acquisitionjust as there are for spoken lan- guage. However, the age of acquisition efiects on sign language processingappeared to be greater in magnitude B. PhonologicalSubstinrtion than those reported for spoken language for identical tasks (Mayberry& Eichen, 1991). There is a potentiallyimpoftant difierence between the two kinds of data that render the comparison illegitimate.The effects of age on the outcome of spoken language acquisitionare for learning a second lan- guage. The efiects of age on the outcome of sign language acquisitionmay be for learning a first language(for reasons previously described). This leads us to speculate that the timing of language acquisition may have greater effectson 2-'Z the outcome of first-languageacquisition than second-lan- ').<-.< guage acquisition, henceforth called the first-language (L1)------t - timing hypothesis. The L1-timinghypothesis is reasonablegiven the efiectsof deafnesson languageacquisition. Children born with hearing AND SLEEP impairmentare heterogeneouswith respect to the ability to Target Sigr Response Sign perceive speech. Small amounts of auditory perceptualskill in early childhood can lead to the acquisition of spoken FIGURE1. Examples ol a semantlc-lexlcalsubstltutlon (panel A) language, ranging from impoverishedto complete develop- anda phonologlcal-lexlcalsubstltutlon (panel B). lllustratlon by (Geers @ ment & Moog, 1987). For some adult deaf signers, BetURaskln' R.l. MaYberry. therefore, ASL may be best characterized as a second languagebecause they acquired a spoken languagein early The resultsof these two studiesdemonstrated that as childhood. For other adult deaf signers the scenario may performanceon sign languageprocessing tasks improves, have a more unfortunate outcome. Some adult signers comprehensionand memoryfor meaningimproves in tan- whose hearing losses are of a congenital and profound dem.We interpretedthese results to meanthat increasesin nature may have acquired only scant spoken language in performanceaccuracy reflect deeper, or more complete, early childhood prior to acquiring ASL at an older age. For processingof linguisticstructure. Inaccurate performance such individuals,ASL may best be characterizedas a first reflectsshallow processing, that is, beingintermittently stuck languageacquired atypically late. at the surface-phonologicallevel of languagestructure (May- Thus, the unusual circumstancesof ASL acquisitionallow berry& Fischer,1989). us to determinewhether the age limitationson the outcome In a thirdstudy, Mayberry and Eichen(1991) determined of languageacquisition are uniform for both first and second whetherthe processingefiects uncoveredin the first two languages.The answer to this question has importantimpli- studieswere due solelyto lengthof sign languageexperi- cations for theories of language acquisitionand critical peri- 1261 AEpuisitio^Altet Childlwd

Possiblc 1.00 -.- Ll-Ttming 0.e0 '-'-s"' €a AgeOnly L= E o.8o

at E o.7o 8 ^F 0.60 Method I J The L1-timing o.5o hypothesiswas tested with a matching 2 design. Late-secondlanguage learners of ASL were matchedby age (andsex where possible) to threegroups of 0.40 first-languagelearners of ASL: late-firstlanguage G3 5-8 learners, 9-13 9-15 nativelearners, and childhood Nuivc Childhood krc-Firsr learners.Because the sub- krc-Sccond jects' acquisitional Age of ASL Acquisition historiesare crucialto the experimental Group design,they are described here in detail.ffable I showsthe way in whichthe four groupswere matched.) FIGURE2. The L|-tlmlng hypothesispredlcts that performance wlll decllneprlmarlly In assocla$onwith age of flist-language acqulsltlon and less so In assoGlailonwlth age ol seion-d- Subjects language_acqulsltlon.!f 9se only predlctsprocesllng outcome, thenperformance wlll decllne In assoclationwlth age of ASL Thirty-sixsubjects with contrastinghistories of sign lan- acqulsltlonlndependent of whether lt was a flrst or second guage language. and spokenlanguage acquisition were recruited and tested.To controlforpractice efiects, only subjects who had usedASL continuouslyfor at least20 yearswere included. ods. Answering it requires us to examine the processing (Mostsubjects had considerably more experience than this, performance of two distinct kinds of late learners of ASL. as Table 1 shows.)Subjeds were placedinto four experi- (Late is definedhere as late childhoodor older.) one kind of mentalgroups according to acquisitionalhistory with ASL late learner is the deaf signer for whom ASL is a second and spokenEnglish. Three groups of subjects prelin- 'and were languagelearned after childhood-a late-secondlanguage- gually (congenitally)deaf used ASL as their primary because he or she aicquired spoken language in early means of communication.They acquiredASL as a first childhoodas a first language, that is, a bilingual.The other languageat threedifferent age ranges:0-3, S-€, and g-19. kind of late learneris the deaf signer for whom ASL is a first Onegroup of subjectswas posflinguallydeafened and used language learned after childhood-a late-first language- both ASL and spoken English,ASL when in the Deaf becausehe or she acquired scant spoken languagein early Communityand spokenEnglish when in the hearingcom- childhoodprior to acquiring ASL, that is, a monolingual. munity.2 -timing The L1 hypothesis predicts difierential performance For the presentstudy, age of acquisitionwas definedas on ASL processingtasks for the two types of late learners. the initialage at whichthe subjecthad regularcontact with Specifically, subjects for whom ASL is a late-first tanguage otherdeaf individuals who usedsign languageas a primary should perform more poorly than those for whom ASL is a means of communication.This informationwas obtained late-secondlanguage. (Figure 2 shows the data predictedby throughin-depth interviews conducted in ASL.Because this the L1-timinghypothesis.) Alternatively, if the age limitations eventis so salientto deafindividuals (and their famities), they on acquisitionare always uniform, independentof whether the acquisitionis of a first or second language,the perfor- manceof the two groups of late learnersshould not difier (as The implication here is not that all posilingually deafened individuals acquire also shown in Figure2). Finalty,the most completepicture of ASL and assimilate into the Deaf commu-nity. Many, possibly a majority, oo not.Hovever, testingthe L1-timinghypothesi6 requires'posflinlualf deafbned the Ll-timing hypothesiscan be obtainedif we also examine subjec'tswho did so.

TABLE1. Samplecharacterlsilcs.

Age of Age ofASL Years of ASL Chronologlcal hearing loss acqulsltlon experience age

Group Range Range Range Range MFn

Late-second 9 (8-12) 11 (e15) 50 (2s41) 60 (3u721 63 9 Late-first Birth (0) 11 (s-13) 54 (2&61) 60 (4u72) 63 9 Ghildhood Birth (0) 7 (il) 51 (31-€s) 61 (37-711 54 9 Native Birth (0) Birth (0-3) 51 g#n 51 (4H4 27 I 36 1258-1270December 1993 1262 JounulofSpeech anl Heaimg Rseatch subjectreported languagewas neither used nor known' Each havec|earanddetai|edmemoriesofit,whichtheyreadi|ythatheorshewastransferredtoaresidentia|schoo|be. oescriue.Theva|idityofsubjects'se|f-reportsofwhenthis spokenlanguage was deemedinsufiicient by recent studies' each causehis or her h"ppened is iemonstiated purioses.Annougn no formalassessment of """.t (defin9din thismanner) to predict for educationat rho*ing iie of acquisition languageskills was given,only 1 subjectreported a varietyof tasks (Emm9ryy&-Corina' spoken sign pe-r{ormanceon to use speechfor Lommunicationpurposes' The Maybbrry-&Eichen, 1991; Mayberry beingable rdgoi Mayberry,1993; thesesubjects had usedASL ranged from 28 1988, 1990)' situationis Lft,i ; time & Fischer,1989; tlewport, $he meanof 54 years'They ranged in agefrom in Canadaif andwhen io Oi y""ts witha identicalto askingengiisn speakers with a mean of 60 years' speakers'a memorable 40 to 72 years ih;t associatediaity-witn French Ninecongenitally deaf subjects be- groups had the following chitdiood learners. The four eiperimental signbetween the agesof 5 and8 yearswhen "u"nt.l g*i" Lcquire characteristics.a-t.to""condlanguageleamers.Ninesubjectshadnor- in i schoolwith otherdeaf children who used in"y parents ;id "nroliedilgrage. Each subjecthad normallyhearing mal hearingtnrougf,outlarg childhoodand spontaneously with them during in *fro n.iinei knew nor used any sign sf,ofen Englishai a first languagebeginning acquireO cnitonoodorado|escence.Thesesubjects|earnedlo.signin subieciwas thus an unquestionable.caseof int"nry. Eich immersionsetting in residentialschools for deafchildren' icquisitionof ASL'The causeof deafness an second-language ihe residentialschiol was the first educationalexperience in day foral|subjectswasvira|infection(accordingtose|f.report)'for 7 subjects;2 othersubjects began their education notused; meningitisinsevencases,measlesinonecase'andenceph-ctassesfbr deafchildren where sign language was in another.Afier becomingdeaf, these subiectswere (atage 8)' alitis theylater were transferred to a residentialschool educatedin the companyof congenitallydeaf and the rrOt"qr"ntly Ot intt" 2 subiects,1 reportedhaving no speech whoseprimary language was sign or-PSEin the children QS-U reportedhaving limiied speech' The lengthof time cases,but some version9f MG.ElManually otn", n" t"jotity of had usedAsu ,"nged from 31 to 64 yearswith a one case as describedbelow)' For the subjects years Coded'Englisn-in mein of 51 years.They rangedin agefrom 37 to 71 part,'thelate-second language subjects acquired sign roit with a meanof 61 Years. inanimmersionsetting.on|ylsubiectreceiveddidactic in Nativelearners.Ninecongenita||ydeafsubjectsbeganto instructionin how to sign' Six subjectswere educated deaf. schoolsfor Jeaf chitdrenafter becoming language residential ".qui'"ASLininfancy(orveryearlychi|dhoodilt*gcases).Sevensubjects had ieaf parentswho usedsign Threesubjectswereeducatedindayschoo|sandc|assesfor*itn tn", beginningat birth. Two subjectshad normally childien.The lengthof timethe subiectshad usedASL of deaf hearingparenis butiegan to learnsign at 2 and3years from 28 to 6/years with a mean of 50 years' The iangeO ,"'rp"ctiveiyin preschoolllot deaf childrenwhere the rangedin a$eirom 37 toT2yearswith a meanof 60 sunieAs "g"r"'ngr"g'" of insiructionwas MCE(Manually cod.ed English). years. and onE,uoi"ct hada deafaunt and unclewho lived nearby Subjectmatching.Eachsubjectinthe|ate.second|an. (s years) withwhomhe/shehadfrequentcontact.oheperformanceof guagegroup n *Itched by chlonologicalage 5 native prelin- these2 subjectswas indisiinguishable from that of the io r-suoieciin "" each of the followingthree groups.of ease learnerssoihey were included in the nativegroup.) For guallydeafsigners,late-firstlanguagelearners'nativelearn- ofterminotogy,tnisgroupisca||edthenative|earnersby anO cnitOnoodlearners. Subjects wgrl additionally parents. Ers, whichis meantthat ihey acquiredASL from their matchedforsexwherepossible,asshowninTablel' yearsand The nativelearners ranjed in age from43 to 67 l_at*frrst language iearners.Nine congenitally deaf sub- had usedsign for nearlyas long,as Table1 shows' jects beganto lcqulre sign lang-uageafter ea.rlYchildhood and Sampleiharacteriitics' As previouslydesqibed betweentheages.ofgand13.Eachsubjecthadnorma||y ASL experi- lan- shownin Table1, the groups'mean length of hearingparents who neitherknew nor used any sign A one-way Likethe *"t 51,51, 54, and 50 yearsrespectively' gu"g"iuith himor her in childhoodor adolescence. for length learn- "n." of varianceshowed no significantefi_ects i-"t"-.'."condlanguage tearners, the late-firstlanguage : n's']' This sign "n"rv.irof srgn language experience [F(3,32\ O'24' ersacquired sig-n inln immersionsetting. They acquired indicitestnittn-e groups differed primarily in theage atwhich whentheyenro||edinresidentia|schoo|sfordeafchi|dren time theyfirst began tjacquire ASL and notin the lengthof (betweeniheages of 9 and 13).Prior to attendingresidential they had usedit. they nid attendeda varietyof schoolswhere sign icnoob, Meanchronological age of the groupswas 51.' 61' 60' and 60 years respectively,as previouslydescribed' A one-way varianceshowed no significantefiects for chro- all anaiysisof 3lndividualswho assimilateinto ths Deaf communitydo not necessarily :1'51' Thisindicates that the the language tor"ili.tr age [F(3,92]l n's']' havethe samedegree oiAsu proficiencyeven though.thgv,use Althoughthe The situationis identical.for example'to an age-iratchingacross groups was successful. iJ intlrpersona.6mmunica$on. highlyproficient in years' both English-speakingcommunitin *tti"n manymembers aro t-."n age oi the groupswas older,50 to 60 are lessproficient (such as Efiii;h tJucnaiaoun naiu6 ipeakers)but others were representedin eachgroup .p"afeoi: despitethis variation, communication Vorng"t;nd olderlubjects children.|]jtiil'or second-tans;S" thosewith less as Table1 shows' il ;-o""ur sp6akersadapting to *itn i rangeof 37 to 72 years, Thus,iOentidcaiion't "tr,liotJpioncientix't anO assimilation into the DeafCommunity 1 shows the sex distributionof the ilfi;ffit. studiescited here Inspectionof Table lo", not implyuniform p'on"i"n.v in ASL The research a wid6 rangaof proficierrcy.relale{to the sarne second-|anguagegrouptofavorma|esoverfema|eswitha ,r,*, n"t n'sl usersnJu" in the produceuariatilit' in ipoferitangtiage.(For descriptions of ASL of .67. ti ti4, Wolfi and Brown (1987)found faAorsthat 1988'and ratio the DeafCommunity, ;;le;#' tsag, Faoden& Humphries' preva|enceofmeningitis-inducedhearing|ossinthegenera| Schien,1989.) Mayberry: First-Language ,kqu*ition After Childhood 1263 popurationto be greaterfor maresthan femares with a ratio .68. Thus, the male of Each stimutussentence bias of in" .""ond-language was foilowedby a 30-secinterval reflects poputation group duringwhich the trends. ey contrast,the native-rearner subjectresponded. groupfavors femares, Short-termmemory which .io"r not reflecttne-poprration spanfor sig.neddigits.To compare to the bestof our knowredge. performanceon the sentence io*"u"t, it is importantto recairtast< viitn a word recarl that the recruitmentpoor-for note task (wherethe wolds native fearnersis rim*ed are highrypracticed), sTM recafr causethey constitute be- signeddigits was for tess than 10o/oot th; ;; arsotesteo.-irrr prrpor"';iil; (Rawfings poiutation son was to compari- & Jensema, 1977). determinewhether difierenc", in The hearing recaframong nsi sentence revetsof a, the subjectswere the groupscourd be attribuiro p-r"-existing eachsubject not assessedbut difierences io describedhim or r,"ELri beingprofoundry amonsthem in srrt,n ;,4;o5i ln pifotresearch deaf. sessed d;;. wasas_ (Maybeny,1994i, il; ",accurasy by administeringthe digitspan self-report of thesubjects, (weschrer, subi"rt'o?'tn"wAts was ascertaineooyi6'J"n the 1gg1).Both-ton"ati and backward jects' Mean hearingof 16 sub_ assessed. span were and median *", stimuriwere 14 rists ot sinde'Jigiirin"t agedacross L"*rg-,""itroro iio ie 1"u"r- randomsequences were soo, lk, 2kHz, tSO)-f;;the better of the numbers1 to g. Lists ear. rengthfrom increasedin twg to nine digitswittr two triars The tistswere air"-.n bngtn. signedov a ieat';",i* signei";-vJieotapeo. Experimentat procedures The signed dis[s *9ie proJr.Lo at ir,e secondwith i,intonation,, ;; ; one per ASL processing a normalfist in task.Thesign languageprocessing srightpause Asi-th;i is, witha was immediaterecat task between.ga.!digit and a return of rongand compfexASL sentences. restingposition-after. of the handto sentencerecarf *'"r the rast'digitof each ur"d Jrln" dependentmeasure presented iiri. blgit, were causeprevious research be- in signwith no ,p"""f, o.il;";;;;;i. had shownit to o" nid;ry sensitive Testing to age of acquisitionin ,""ra o-i:o_!::e,1.[ ,rOiect was testedinlividuaily scribed) yays (as previousfyde- by two fluent signers and becausethe presentstudy lone naiive and ;;;;-native). theseprevious was an extensionof s ubjectswere tord- that tnbv wo resutts(Mayb;r.y & Edh;;6;;Mayberry urcisee videotaped sentences & Fischer, givenin ASL an!]nlru"t"'O 198_?.,fne'pr'.nofinguistic -imitation) to i"peat in signfanguage each immediate ,'"iion"f" for using stimurussentence as recari 10r eticiteJ accurateryas possibreiirmediatety language as a measure of after watchingit. subjects processingis ihai recart *"iJ warnedthat the stimurus requires of comprexsentences sentenceswere_,:lg^gd."orpi", a highdegreg o{r3ngr"g" proficiency. by designin an efiortto recat fanguage The abirityto elicit mistakes.The experimeniaf stimuriwithoJt comprer,ension, practice rist-wasp?.J"i by four rs not characteristic or echoraria, sentences.Trt; stimuri*"r" presented of normaffanguage processing. color on a 26'nch over' when the More- videomonitor. A cororviJeo-camera ranguagestimiriarJ 'i"g-lii monitor pracedbeside the sentences,as in comprex recordedthe subjectr;,lgnperformance. the presentstldy, ,roj"&, For consistentmistakes pbtn ,lke highly the digit-soan witninano betweensubjects) the videotaped lT!,;?roi""tl'were instrucredto watch yieldinsights into-howtnev that signerand repeatthe signed mavtlprocessingthe stimufi, separatetwo digitsin the previousresearch ltas as conditions,forward and reversed demotirtr"t"o*- uyrqv.,r'rrv(Mayberry&q Eichen, restins seguence. tt:1iy1b"rry & Fischer, forowedtrre stanoaiJ prl""oilffi; rs89J. schfer'lggl) d;L ** Jentencestimuri.The and was gtopp"i *i"n the stimurussentences were eightASL recalf correc'y subjectfaifed to sentencesused in previou, two trials bi tn" ,"me fength. ,"r*r"h. (Mayberry& Eichen, determined Span was 1991).The senteT",ygrg to be-the rongesiJigit rist rength tongfianging from 12 to 15 sequencewithout recaredin signs'witha medianol base error. rlsisnsl-and comprex(with conjoined or refativizedcfauses). Thele linJr of stimutiwere used two reasons.Long sentences for circumventceifing effects Pertormance Analyses nativeand chirdhooarearners for ;;sr;;;"#a, sen- tencesof shorterfgnOthl Se nten ce re fhetranscription, sentences Lrroi.-dorpf", the 7 !!, coding, andanaf ys is of requirea.good gtri""rify -6ng oinsl"n-A_*ithout subjects' senten." ,"*[ lonsisteo and recat. syntaxto understand identicaf ,""Jr"f steps Finaty, o"."ri" sentences to thos.eused in pr"utrr ":i term memov exceedshort- Eichen,1991; -research(Mayberry & tslytl,_.p1,. thl'y-must be tinguisticaly Mayberrya Fis-#1, 19e9). cessedand cannot pro- sign performance ln tne;rst step, simpry'oei5ca'ed in a tist was frst t anscrioeoinoepen;;;v stimulussentences fashion.The coders who by two are givenin the appendix. were unawareof the rroi"&['".q,iirition"t Tl" erghttarget history' Both - ,"nt#.". ;";; were highfy pr".ti""o *itti j."J:::"rf'lfl lang uag e transcription.-ei.fi ni, k,:iiot sign 9:*'q*;rigiJ,^:ndvideotao; jfff,:#"3 .o'i Ji rs"o a transcriptio were given in ASL, previousfydevetoped n code which is-a-separatetanguage for tnislrrpo.". The English'the sioner from elaboratedtranscription code is an used no ap"".n or mouthmovements. *neli[-a separate Thetarget s"ntEn."s Engfishword represents and unique werenesied randomfy within eachASL fexicarstem imentarrist of 30 an exper- morphemeof and bound totaf r"nt"n"".-piesented consecutivery.n the subject,s,"rponr".

4The dataanarlais presented here is rimitedto because !ffi::J,#:S::f,:"":f ,*lyru:3:,[il'fl _"igll""t"nces of the 3; ,U":,flffiJ":""#F"J:",fit i'r:dir*Fin:w, ;:n#n::;5?i:?:::xtrfr::,""9,3,:f:*ffi ti:""l"#;nH jf: 36 1258-1270December 1993 1264 Jounwl of Speechand Heaing Research

productlon In the secondstep, the transcriptionsof the two coders TABLE 2. Response length and sign rate. were comparedstem by stem and bound morphemeby Signs/Response Seconds/Slgn boundmorpheme in the presenceof, andin referenceto, the originalvideotaped performance. Transcription difierences Group weie resolvedthrough discussion and repeatedviewing of questionby the two coders.Transcription Native 12.19 1.4 0.74 0.10 the performancein 2.4 0.83 0.11 quite from94 to 100o/oagreement Childhood 12.36 reliabilitywas high,ranging Late-first 1',,.67 2.4 0.65 0.24 acrossall stemsand inflections.High reliability was readily Late-second 10.22 1.8 0.83 0.30 achievedbecause both coderswere highlypracticed at the task and the signed utteranceswere highly predictable (beingvariations of the samestimuli). numberof roottexical items (base signs) each subject gave In the thirdstep, mismatches between the stimulussen- in eachresponse was summedand analyzed. tenceand the subject'sresponse were notedand described The groupscould not be distinguishedon the basisof their phrasal, sentence linguisticallyat the lexical,inflectional, and responselength : 2'11,n's']' As Table2 shows,mean mis- [F(3,32) tevels.A code that categorizedthe varioustypes of responselength was similaracross the groups.This result response. matcheswas then appended to eachtranscribed extendsprevious research by showingthat earlyand late leam- purpose(May- The codewas previouslydeveloped for this ersof ASI- includinglate-second language leamers, cannot be of berry& Eichen,1991). In the fourthstep, the transcription distinguishedsolely on the basisof responselength. The result each responseand its appendederror code were entered furthershows that any processingdifierences alrong earlyand intoa computerprogram, SALT (Miller& Chapman,1984). late leamersare not due to basicproblems in the parsingof The programwas designedto compareutterances from two lexicalitems in givenASL sentences. linguistic speakers,and we usedthis capability to compilethe Sign production rate.The subjects'signproduction rate similaritiesand difierencesbetween the stimulussentence was measuredby timingthe durationof eachresponse in andthe subject'scoded resPonse. hundredthsof a second,beginning with the initiation of lexical 1991)'the As in previousresearch (Mayberry & Eichen, movementin the first sign of the responseand endingwith per-. subjects'responses were analyzedfrom four different the releaseof lexicalmovement of the finalsign (Uddell& (a) re- spectiveswith respect to the stimulus sentences: Johnson,1989; Padden& Perlmutter,1987). Response (b) and sponse length and sign productionrate, lexical durationwas then dividedby the numberof signs (base (c) preservationand inflectionalpreservation and change, lexicalitems) in the particularresponse. This yielded a sign sequencingof syntacticcoristituents, (d) grammaticalac- productionrate in hundredthsof a secondper sign for each STM ceptability,and (e) preservationof sentencemeaning. response,which was then averagedand analyzed. purposesof clarity' for signeddigits was also anallzed. For The groupscould not be distinguishedon the basisof their for each type of analysis are given -- computationaldetails sign articulationrate [F(3,32) 1.128,n.s.], as Table 2 results. belowin tandemwith each set of associated shows.This resultextends previous research by showing that earlyand late learners,including late-second language tearners,cannot be distinguishedfrom one anotherwith Results respectto their rate of sign articulation.The resultfurther For'thestatistical analyses, each categoryof performance showsthat any processing difierences among the groups are analysisw€ts computed and analyzedseparately. Sentence notdue to the laterlearners producing signs at a significantly recalldata were analyzed with one-wayanalyses of variance slowerrate than the early learners. (unlessothenrise noted). The between-subiectsfactor was age of ASL acquisitionwith four levels:native, childhood' and Change late-first,and late-secondlanguage learner groups, as de- Lexical and lntlectional Preservation datawere scribedabove and shownin Table 1. Digitspan Recalloflexicalstems (base signs) and bound morphology of anallzed with a two-way, repeated-measuresanalysis (signinflections) was examinedwith respect to (a)preserved variance.The between-subjects factor was age of acquisition nature of lexical recall, (b) preservednature of bound- was recall withfour levels of group.The within-groupsfactor morphemerecall, and (c) linguistictype of lexicalsubstitu- order. sequencewith two levels,forward and reverse tions. Preserved lexicat stems. Overall accuracyof lexical recatlwasmeasured by scrutinizingthe lexicalstems given in Response Length and Rate eachresponse. For this measurethe proportionof signsin Responselength.lf age of acquisitionefiects are associ- eachresponse that were identicalin phonologicalform and atedwith problems in the fine-motorcontrol and coordination meaningto thatof the stimulussentence was computed. The requiredto sequencelong sentences(13 to 15 signs in proportionfor each responsewas then averagedand ana- length),or, alternatively, if the efiectsare due to an inabilityto lyzed. parsethe.lefcal itemsof the stimulussentences, then the Age of acquisitionsignificantly afiected the extentto which responsesof late-firstand late-secondlanguage learners the lexical stems were recalledin a preservedfashion shouldbe abbreviatedin comparisonto thoseof nativeand [F(3,32)= 3.82,p <.05].AsTable 3 shows,the efiectwas childhoodlearners. To determinewhether this was so, the due to the nativelearners who recalledsignificantly more Mayberry: First-Language Acquisitiotr Afrcr Childlwod 1265

TABLE 3. Proportlon of stlmulus lexlcal stems preserved In Linguistic Level of Lexical Substitutions each response. # lcmanuc Group SD ""o..'' Phonological Native 0.72 0.05 0.60 6 Childhood 0.56 0.13 o Late-first 0.56 0.09 F b [at+second 0.s6 0.18 o 0.40 0

L preserved three o lexicalstems in a fashion than the other EL o groups, late-first,and late-second language learn- L childhood, 0.20 ers (p <.05 for eachcomparison, Student-Newman-Keuls). er Thefinding extends previous research by showingthat native learnersdisplay greater skill at preservedlexical recall than 0.00 signerswho acquiredASL at later ages, regardlessof G3 5-E 9-13 9-15 whetherthey are first-or second-languagelearners. Nativc Childhood larc-First rate-Sccond Pre*rved bud morphemes.To measurethe preserued Age of ASL Acquisition natureof boundmorphemes (botl inflectionaland derivational) Grcup in sentencerecall, the numberof boundmorphemes the subject recalledin a preservedfashion (i.e., identical phonological form FIGURE3. The meanproportlon of phonologlcaland semantic' wes com- lexlcal substltutlons produced by the sublects durlng sentence and morphosyntacticfunction to that of the stimulus) recall as a functlon of age of ASL acqulsltlon and first versus puted,independent of wheher the basestem was recalledin a second languageacqulsltlon (for total substltutlons produced preservedfashion. Bound morpheme recall was treatedas a by each subiea summed across all responses). singleresponse category and summedover all responses.This necessarybecause there w€tsan unequal computationwas solely phonologicalin nature was dividedby the total number differentkinds of ASL bound morphemes numberof ssreral of substitutions.Likewise, the sum of lexical substitutionsthat (.e., classifier,ad- representedin the ASL stimulussentences were solely semantic in nature was divided by the total verbial,and aspectral inflections). numberof substitutions.Using. proportion scores ensured the morphemesw€ls unaffected by age Meanrecall of bound comparability of the comparison across subjects because as Table4 shows.This resultparallels that of of acquisition, early leamers made feWersubstittttions overallthan did late previous in'which learnerstended to recall research native learners as indicated by the results shown in Table 3. more preservedbound morphemes than signerswho ac- Phonological and semantic lexical substitutions were ana- quired but the trend did not reach ASL at older ages, lyzed with one-way analyses of variance by ranks. the efiect. significancebecause not all subjectsshowed As previous research predic'ted and Figure 3 shows, the level lexical substitutions. The lexical Unguistlc of tendency to produce lexical substihrtionsof either a semantic or for stimuluslexical stemsthe subjectsmistakenly substituted phonological nature w€ts €lssociated with age of acquisition. itemswere in scrutinizingthe linguistic examined detailby Across ilTethree groups of first{anguage groups (native,child- relationships these substitutionsand the stimulus between hood, and latefirst language learners),the proportionof total lexicalitems replaced.Most lexicalmisrecalls were of they lexicalsubstitutionsthAtweresemantic in naturedeclined as age two constrastivetypes, phonologicaland semantic,as de- of acquisitionincreased (f = 13.26,df :3, p <.01, Kruskal- in Figure1. scribedin detailabove and shown Wallis).At the same time, the proportionthat were phonological For the present the proportionof total lexicalsub- study, in nature increasedaqoss the three groups 8.8+, df = 3, p (across responses)the madethat were ff stitutions all subject <.05). Hotlrrever,the relationshipbetween age of acquisfionand phonological,was of the two types,semantic or computed linguistic-enorpattem did not encompassthe late-secondlan- producedby and anallzed.First, every lexical substitution guage leamersin the following manner. was all eightresponses. There the subject summedacross Even though the late-secondand late-firstlanguage learn- werefive total lexicalsubstitution: (a) semantic, categoriesof ers acquiredASL at the same late ages, the linguisticpattern (b) phonological,(c) unexplainable/ambiguous,(d) unintelli- of their lexicalsubstitutions difiered, as Figure 3 shows, The gible,and (e) phonologicaland semantic.To derive both late-secondlanguage learners showed a pattern of lexical proportionscores, the sum of lexicalsubstitutions that were substitution that was more akin to that of the native learners in terms of predominant linguistic-errortype. They made TABLE 4. Proportlon ol stlmulus-bound morphemes preserved mostly semantic lexical substitutionsand few phonological acrogs all responses. ones (late-secondlanguage learners! 12 : 135.53,F <.01; nativelearners: : 135.53,p <.001, median-signtestwith Group SD x2 Yates correction).The childhood learners also tended to Native 0.42 0.13 make more semanticthan phonologicallexical substitutions Childhood' 0.26 0.15 but to a lesserdegree than native and late-secondlanguage Late-first 0.26 0.15 learners (Xt = 6.06, p <.05, median-sign test with Yates Late-second 0.34 o.22 correction).By contrast, the pattern of lexical substitutions 36 LZ58-L27O December1993 1266 lclyrnul of Sp"ech atll Heaing Reseatch

Level Charecteristics of Responses TABLE 5. PropOrtlon of Stlmutus grammatlcal constltuents Sentence preservedIn each resPonse. 1.00 # Crraomatical Group ""o..- Seoantic Rcluiolts !t, o.71 0.04 o.8o Native Zo 0.s3 0.16 c Childhood e, late-first o.47 0.09 c, late-second 0.69 0.14 a ? 0.60 a produoedby the late-firstlanguage learners was unique: o t They produted nearly equal proportionsof phonological o = p = O'41' 3 0.4o subititntionsand semanticones (xt 0'669, t- I median-signtest withYates correction). These findings sup- t port the tt-ti*ing hypothesis.The age at which a first I lastingefiects on the way in which i"ngrag" is acquiredhas G3 9-13 9-15 lateradulthood. 5-8 l3nguageis processedin Nativc Childhood l:rc-First [:rc-Scco'nd Age of ASL Acquisition GrouP Becatl of SYntactic Constituents responses of the subjects' FIGURE4. The mean proportion of thesublects'total The degreeto whicfrthe constituentsfiucture andsemantlcally p-arallel to (i.e.,subiect thatwere grammaticillybcceptable response;minored x1d of the stimulussentences iiie-sil1nutitorsubiects groufed by ageot ASLacquisltlon and or obiect-nounphrases, verb phrase,adjective and adverbial flrst versussecond language acqulsltlon phrases,and so forth)was anallzed.The syntacticconstih1ents of eachresponse were first categorizedaccording to type,then intheir response was examined, independent matcfredby sequenceto that of the stimulus.This procedure ulussentences or grammaticalacceptability of the yieldedtheproportion of syntac{icconstifuents each subject gav.e of the syntacticstructure rationalefor this analysisis that successful in eacfrresponse thatwere of boffithe sametype and the same response.The processingtypically entails memory for sentence orderas that of the stimulus. tanguage of its originalstructural form for both Age of acquisitionsignificanuy afiected constituentrecall melning independent Bellugi,1982; Sachs, 1967)' A = 13.77,p <.0011;as Table5 shors' The effectwas speechlnd sign(Hanson & lFtg,gZ) judged havepreserved the intendedmean- primaritydue to the ndive and late-seoondlanguage leamers responsewas to if it conveyedthe semanticgist responsesminored the cOnstitrentsfructlre eind se- ing of the stimulussentence wtrose relations,that is, same quencingof the stimulussentences b a greder extentthan of tne stimulusin termsof semantic actions,and relations among boh the childhoodand late-firstlanguage leamer group actors,relations among actors, thoseof judges(unaware of the acquisitional <.05 br ead, comparison,Student Nerrman-Keuls]' This actorsand actions.Two [p independentlycompared. each re- resultis predictedby the Ll-timinghlryoffiesis. historyof the subject) sponseto eachstimutus sentence and decided whether the semanticrelations of the stimuluswere the sameas those judges Sehtence-Level Pertormance given in the response.The responsesthat both agreedupon were then summed and anallzed. grammaticalacceptability Grammaticat responses.The nge of acquisitionsignificanfly afiected the subjects'ability to withoutregard to of the subjects'responses was €Fsessed maintainthe general meaning of thestimulus serilences [F(3'32) responses particularsemantic or syntacticcontent. Subjects' = 14.52,p<-.OO1l.As Figure 4 Shows,preservation of stimulus (unawareof the were judged by two native AsL learners meaningin the subjects'responses declined with grammaticalor sentence subject's-acquisitionalhistory) to be either age of acquisitionacross the threegroups of first- proportionof the increasing ungrammaticalin eitherASL or PSE.The learners.The native leamers significandyoutper- grammaticalby language suqea,s total responsesthat was deemed tormeotne childhoodand late-first language leamer groups;the bothjudges w€Ni then analPed. childhoodleamers, in tum, significanflyogtperbrmed the late- afiectedthe extentto which I Age of acquisitionsignificantly first languageleamers [p <.05 for eachcomparison, student acceptableresponses the subjects gave grammatically ruewman-Xeulsl.The late-secondlanguage learners performed = 4 shows'The effectwas [F(3,32) 4.87,p <.011,as Figure less well than the native leamersbut also outperbrmedthe languagelearners who gave primarilydue to the late-first childhoodand lat+first language leamer groups [p <.05for each acceptableresponses than significantly fewer grammatically comparison,Student Newman-Keulsl. This result is predictedby languagelearners (p the native,childhood, and tate-second the L1-timing hy'Pothesis. <.05 for each comparison,Student Newman-Keuls).Al- thoughthere was a cleartrend for the nativelearners to give moregrammatical responses than the othergroups, it did not Digit Span reachsignificance. and reverse presirved meaning of responses.The extentto which sTM spanfor signeddigits in bothforward subjects recalledon the subjects'responses preserved the meaningof the stim- order was computedand analyzed. Maybett-12First-Language Acryisition Afur Childlwd 1267

averageone more digit in thefonrard than reverse sequence What is the nature of the advantageconferred on adult [F(3,32)= 28.13,p <.001J.Age of acguisitionalso afiected languageprocessing by acquiringlanguage early in life?The digitspan [F(3,32) = 4.42,p <.05J.Themean span of the presentresults in conjunctionwith previous.research provide groupswas 4.7, 4.2, 4.3, and 5.2 digits respectively. The. digit some hints.The easiestway to organizethese clues is to spanof the late-secondlanguage learners was significanfly eliminatethose processing skills that showed no efiectsand larger than that of the childhoodand late-firstlanguage thenfocus on thosethat did. learners.However, the digit spansof the late-secondlan- Two measureswere undected by age of acquisfion--ffre guagelearners did notdifierfrom those of the nativelearners rate at which the subjectssigned and the totialnumber of (p <.05 for eachcomparison, Student Newman-Keuls). signsArordsthey gavein eachresponse. This meansthat the ln summary,the results of this study show that ASL effectsassociated wifr thetiming of first-languageacquisition are proficienryas measuredby recatl of long and complex notdue to problemsin fine-motor movement and coordination or sentencesis predictedby the timingof first-languageacqui- inparsing surhce pattem sfucture. Thefinding extends previous sition.Multiple aspects of ASL sentenceprocessing perfor- researchby showingthat this is true regardlessof whetherthe mancewere related to thetiming of first-languageacquisition languagebeing processed is a firstor secondone (Mayberry& aq evidencedby the fact that the late-secondlanguage Eichen,1991; Mayberry & Fischer,1989). learnerssignificantly outperformed the late-firstlanguage Severalmeasures were significantly afiected by ageof acqui- learnerseven though both groups began to acquireASL at sition.For example, the late-firstlanguage leamers were partic- the same late ages. These efiectswere (a) preservationof ularlydisadvantaged on the measureof grammaticalacceptabir- semanticroles and relationsat the sentencelevel, (b) ity in comparisonto the othergroups, including the tate-second grammaticalacceptability of responses,(c) preservationof languageleamers. This finding is in keepingwith previous constituentstructure and sequencing, (d) preservation of the researchshowing that the abilrtyto makegrammatical accept- judgments domainof lexicalmeaning independent of surfacephonolog- ability is associatedwith age of second-language icalform,and (e) STM span for highlypracticed signs (digits). acquisitionin speech(Coppieters, 19BZ1, Johnson & Newport, 1989, 1991). present One aspectof sentencerecall was relatedsolely to native In the study, the performanceof the late-secondlanguage grammaticar acquisitionof ASL, namelyrecall of lexicalitems in a fully leamerson the acceptabirity measurewas notsignificanfly preservedfashion (i.e., both surfacephonological form and . differentfromthat of the nativeand childhoodleamers. meaning).Finally, measures of responselengrth and sign One reasonfor this maybe thatthe grarn- productionrate showed no efiects. maticalitymeasure of the presentstudy was quite broad.Re- sponseswere judged grammaticalwithout referenceto the stimulusor signdialect Nevertreless, the finding suggests that syntacticskill, by itsetf,may not be the primarysortce of the Discussion advantageconfened on languageprocessing by acquiringlan- guageearly in life. The L1-timinghypothesis predicts that the age at whicha The timingof first-languageacquisition showed significant first languageis acquiredhas greater efiects on language efiectson severalmeasures of languageprocessing skillthat processing skillsin adulthoodthan doesthe age at whicha are relatedto memoryskill: sequencing of constituentstruc- secondlanguage is acquired.In termsof the presentstudy, turein the sameorder as thatof the stimulus,preservation of the hypothesispredicted that adult deaf signerswho ac- the generalsemantic gist of wordsand sentencesin reration quired AsL atthesame late ages would show unequal skill at to the stimulus,and STM span for signeddigits. The late- processing ASL as a functionof whetherthey acquireda second languagelearners significantly outperformed the languageon schedulein earlychildhood. The resultsof the late-firstlanguage learners on all these measures.This present studysupport the hypothesis.Adult deaf signers who suggeststhat the advantagesconferred by acquiringa unquestionablyacquired ASL as a secondlanguage after languagein earlylife may turn on memoryskill, but how? earlychildhood outperformed their matched peers (for chro- Of all the groups,the nativetearners showed the best nologicalage, length of ASL experience,and sex) who performancefor preservedlexical recall.Native lbarners acquiredASL as a first languageat the same late ageson were betterable than the othergroups to recallthe precise severalmeasures of languageprocessing. The acquisitionof phonologicalstructureand meaning of thelexicalstimuli. The languageearly in life is apparenflynecessary fgr language threegroups who acquiredASL at laterages, the childhood, processing to be carriedout eficientlyin lateradulthood. late-first,and late-secondlanguage learners, all showed Theunique feature of the presentresults is thatthey show diminishedskill at preservedlexical recalr in comparisonto theefiects to be robustand impervious to the linguisticdetaits the natives.This suggeststhat individualswho acquirea oJthe languageacquired early. In otherwords, the timingof givenlanguage after early childhood have processing skills first languageacquisition in developmentafiects language for that languagethat are limitedin someway. Thus,one processing skillsin lateradulthood independent of the spe- importantdifference between the late-firstand late-second cifictype of languageacquired early. Thus, adult deaf signers languagelearners may tie in whetherand howthey circum- whoacquired a firstlanguage on schedulein earlychildhood vent limitationsin languageprocessing. outperformedthose who did not, even though they were The late-firstlanguage learners made unique lexical sub- processing sentencesin a languageother than the onethey stitutionsthat were related solely to the surfacephonological originallyacquired at an earlyage, namely,a secondlan- structureof the signs they were processing.This kind of guage theylearned at an olderage. lexicalsubstitution was unrelatedto stimurusmeaning at the .'a

36 1258-1270December 1993 1268 Jrlrrnulof Speechanl HeaingResearch

secondlanguage into the firstone, if neces- lexicalor sentencelevels. Production of sucherrors suggests cantranslate the a richand detailed semantic . that the late-firstlanguage learner is intermittentlystuck at sary,and thereby access in concertwith previousresearch the surface level of language structure. Other research The presentresults are of age of acquisitionon language suggeststhat this may indeed be the case (Emmorey& showingthat the efiects as memorydemands increase (May- Corina,1990; Mayberry & Fischer,1989). By contrast,the procesJingincrease The presentresutts extend our late-secondlanguage learners made few phonologically b"rry & Fischer,lggg). phenomenonby showingthat it is basedlexical substitutions but mostlysemantic ones. This understandingof the to acquirea languageearly in life. suggeststhat the late-secondlanguage learner, but not the compoundedby failure is neededto uncoverthe precise late-firstlanguage leamer, can rectifyintermittent failures in clearly, more research efiectsreported here; lexicalidentification and sentencecomprehension. natureand locusof L1-timing as to whetherthe L1-timing Why would the late-secondlanguage leamer be able to Finally,the questionarises That is, do the findings circumventprocessing failures and the late-first language leamer efiectsare experimentalartifacts. subjects'sign communica- nof, The simplestexplanation is thattre lat+secondlanguage reportedhere characterizethe sourcesof evidencesug- leamermay use his or herfirst language (acquired on schedule tion outsidethe laboratory?Two here are valid. First, in a eartylife) to circunventthe processinglimitations posed by gest that the efiects reported 4 (1991)asked subjects acquiringa languageat a lateage in at leasttwo wala. First,the previousstudy, Mayberry and Eichen of ASL acquisition)to late-secondlanguage leamer has acquiredgeneral knovledge iadultdeaf signers who variedin age skill on a S-point abouthor languageis sfiucturedin additionto a detailedand iate their everydaysign comprehension to "neverunder- extensivelexicon. Togertrrer these knovvledge sourc€s may help scale rangingfrom "alwaysunderstand" sign skills predictsentence meaning in the face of uncertainty(in the stand."The subjects'self-assessment of their performanceon the ASL pro- secondlanguage). That is, the'late-secondlanguage learner was positivelycorrelated to the presentstudy). Of may be awarethat he or she has "missed"someffiing in the cessingtask (identicalto the task of preservationof stimulussen- secondlanguage and thus activelyseek to fill the "gap" by all the processingmeasures, the sub- guessing.This guessing,in tum, may be guidedby linguistic tence meaningwas most closelyassociated with probabilityis high knovvledgeof boffi a grammaticaland semarilicnature derived jects' self-assessmentof sign skill.The presentstudy if the fom the firstlanguage. inat tne samerelation would hold for the ln addition,the late-secondlanguage learner may use a measurehad beentaken. phonological"recoding"strategy as a memoryaid. Recoding The secondline of evidencecomes from within the Deaf Jacobs signs/wordsfrom a secondlanguage into the first language Community.In describingthe Deaf Community, He (acquiredearly in life) would capitalizeon a well-developed (1989) constructsa typologyof adult deaf signers. (native)phonologicalsystem as a meansof holdingmeaning categorizessigners in'terms of languageskill, which he (alreadyprocessed from the second language)in working believesto be the productof hearingloss, educational par- memory.This strategymay be especiallyimportant to lan- experience,and family environment. Jacobs' categories guageprocessing when the languagewas learnedat a late allel the experimentalgroups of the presentstudy. For prelinguallydeaf ige becauselate learnersare slowerat recognizinglexical example,his adventitioustydeaf adultsand the late- itemsthan are nativelearners (Emmorey & Corina,1990). aduftsfrom deaf familiescorrespond exactly to groups the present Increasedtime to identifysigns/words means that late learn- secondlanguage and nativelearner of as having ers must hold informationin workingmemory longer than study.He describesthese two types of signers nativelearners in orderto computesentence structure and excellenttanguage skill because ". . . theyhad early commu- is prelin' derivesentence meaning. nication,"(Jacobs, 1989, p. 73). His thirdcategory to The late-firstlanguage learner, unlike the late'secondlan- guattydeaf adultsfrom hearing familieswhich corresponds guageleamer, has no auxiliarylinguistic system (acquired in the chitdhoodlearners of the presentstudy. He describes first two earlychildhood) with which to circumventdelays and lapsesin these signersas havingless proficiencythan the families lexicaland clausalidentification. lf this explandionis corect, vpes of signersbecause "They come from hearing whenthey the late-firstlanguage leamer has at leastfourmajor difficulties who havehad troublecommunicating with them /ow- in languageprocessing brn the late-secondlanguage leamer werelittle" (Jacobs, 1989, p.74l.His fourthcategory, hasonly one. The lat+firstlanguage leamer has difiicultywith verbaldeaf adults,is not futly comparablewith the late-first lexicalidentification, uncertain grammatical expectations' an languagelearners of the presentstudy. The languagehe underdevelopedlexicon, and an overburdenedworking mem- asciibesto the fourthtype of signeris worsethan that of the ory.The late.secondlanguage leamer has difiicutty with lexical fourth group of the presentstudy, namelythe late-first identificationtoo. But unlikethe late-firstlanguage leamer, the languagelearners. He describesproduction of signsmixed late-secondlanguage leamer can partial ly remedyd ifiiculty with with gesture and pantomimefor low-verbaldeaf adults. lexicalidentification via grammaticalexpectations (from the However,he also observesthat this type of signer has nativelanguage). The late'secondlanguage leamer expects, difrcultywith ". . . longor involvedsentences" (Jacobs, 1989, of €tsa generalprincipal, sentences to decomposeinto clauses p.74r,which was true for the late-firstlanguage learners and phrases,subjects to take verlcs,some verbs to take the presentstudy. of signers objects,.and so forth. Moreover,the late-secondlanguage The correspondencebetween Jacobs'typology leamercan alleviate the increasedload on workingmemory by and the experimentalgroups of the presentstudy is striking recodinginto the first language(via the phonologicalsystem of becauseeach grouping was derivedindependently by difier- the nativelanguage). Thus, the late-secondlanguage leamer . ent means.Jacobs' typology was based on sociological 1269 . MayberryzFirst'LuryuageAcErkition Aftet Childlwd

Chitd fromwithin the DeafCommunity. The grouping Recent insights. In S. J. SegalowiE & l. Rapin (Eds'1, observation handbook of neuropsych.ology-(pp' present was basedon a seriesof psycholinguis- neuropsych6logy, Volume 7 of of the study 5147), f. gotidr & J. Grafman (Series Eds.). Amsterdam:Else- tic studiesdesigned to determinewhether the age at which vier. signlanguage is firstacquired has long-lasting efiects on sign Mayberry, R.l. (1993). The importance of childhoodto languag^e processingin lateradulthood. acquisition: Evidence from American Sign Language. 1n J' C' language of speech the Ll-timinghypothesis accounts for sig- Gobdman & H. C. Nusbaum (Eds.)' The development In conclusion, perception: The tnnsition from spee_chsounds to spoken words variationin ASL proficienryamong adult deaf sign- nificant ipp. S7-90). Cambridge:MIT Press/BradfordBooks. ers.The hypothesismay not havebeen previously proposed tUiyberry, R: 1.,& Eichen, E. B. (1991).The long-lastingadvant'age becausefirst languages are rarely acquired after childhood in of teaming sign language in childhood: Another look at the critical d l-ang uag e, the normallyhearing population. The resultsof the present period forianluage-acd'u isition. Jo urn al of Mem ory an the phenomenonmay be a commonone 30,48*512. studysuggest that Mayberry, R.1., & Flscher, S. D. (1989). Looking-throughphono- thathas long-lasting repercussions on the languagecompre- 6gicallhape io lexicalmeaning: The,bottleneck of non-nativesign hensionskills of individualswho are bornprofoundly deaf. faiguage irocessing. Memory and Cognition,17,740-754' Mfiler] J.i., & Chapman, R. S. (1984). SALT: Systematicanalysis of knguage tranicripts. Madison: University of Wisconsin, Lan- guage Analysis Lab. Acknowledgments Neivp6rt, E. L (1998). Constraints on learning and their role in tadguageacquisition: Studies of the acquisitionof AmericanSign The researchreported here was supportedby a grant-fromthe Language. Ianguage Sciences, 10, 147-172. NationalInstitute oh Deafnessand OtherCommunication Disorders Hewp6rt,E. L (1-990).Maturational constraints on language learn- (DC00231).I thank Drucilla Ronchen for tireless ASL consulting and ing. Cognitive Science, 14, 147-172. iubject reiruitment,Elten Eichen for.endless help transcrhing and Oyarira, 5. (tgze). A sensitive period for the acquisition of a anaiping ASL utterances,and Shari Baumand MarthaCrago for nonnative inondtogical system. Joumal of Psycholinguistic Re- careiuttyreading earlier versions of the manuscript.| especially search, 5,261-285 gratefr.rito.thesubjects for their wiltingparticipation and"T numerous Oyama, S. (1978). The sensitive period and comprehensionof insightsinto languageand deafness. speech. Working Papers on Bilingualism, 16,1-17- Padden, C., & Humphrles, T. (1988). Deaf in funerica: Voices from a culture. Cambridge: Harvard University Press. Padden, C.A., & Pirlmutter, D.M. (1984. AmericanSign.Lan- References guage and the architecture of phonological theory. Natural Lan- guage and Unguistic Theory,5, 335-375 Columbo, J. (1982). The critical period concept Research, meth- pe-ntidtO,W. G. (tSSg). Speech anQ brain mechanisms.Princeton, odology and theoretical issues- Psychological Bulletin, 91,260- N.J.: PrincetonUniversitY Press. 275. Rawlfngs, B., & Jensema, c. (9m. Two studiesof the families of coppleters, R. (1984. Competence difierences between native and heaiig' impaired chitdren (Research Bulletin, Series R. No' 5)' non-native speakers. I-anguage, 6ts, 54+573- Wasniignoir, D.G.: Gallaudet University, ffice of Demographic Curtlss, S. (1977). Genie: A psycholinguisticstudy of a modem-day Studies. "wild cllild." New York: Academic Press sachs, J. S. (1967). Recognition memory for syntactic and semantic Emmorey, K, & Corlna, D. (1990). Lexical recognition in sign aspects of connected discourse. Perception and Psychophysics, hnguale: EfiecG of phonetic structure and morphology. PerceV 2,437442. tual and Motor skills, 71,1227-1252. Schien, J. D. (1989).At home among strangers.Washingfion, D'C': pronounceforeign FleEe, J. E. (1984. A critical period !or,l_eamingto Gallaudet UniversitYPress. languages? Applied Unguistics, 8, 162-17i7. Scovet, T. (1989). A {ime to speak:A psycholinguisticinquiry into the Flege-,J.E., & Fletcher, K L (1992). Talker and listener efiects on criticat pirioa for human speech. Cambridge: Newbury House. th--eperception of degree of foreign accent. Journal of the Acous- Skuse, O. H. (tgAA). Extreme deprivationin early childhood.ln D' tial Societyof America,9t, 370-389. Bishop & K. Mogrford (Eds.), l-anguage development in excep' Geers, A, & Moog, J. (1987).Predicting spoken languageacquisi- tional circumstaices (pp. eg-le). Edinburgh: Churchill Living- tion of profoundly hearing-impaired children. Joumal of speech stone. and Hearing Disorders,43,8L94. snow, c. (1987). Relevance of the notion of a critical period to Hangon, V. L, a Beltugl, U. (1982). On the role of sign order and languageacquisition.In M. Bomstein (Ed.), sensitive_p-eriodsin morphological structure in memory for American Siqn Language deieto-pmenti t nterdisciptinary pe rspeclives (pp. 183-209). Hills- seniences. Journal of Verbal Leaming and Verbal Behavior, 21, dale, N.J.: L. Erlbaum 621433. weschfer, D. (1981). weschter Adult lntelligence scale'Revised. Jacobs, L M. (19891.A deaf aduft speaksout. Washington,D.C.: New York: The Psychological Corporation. Gallaudet University Press. wftbur, R. (1987). American sign language: Linguisticand applied Johnson, J. S., & Niwport, E. L (1989). Critical period efiects in dimensions.Boston: College-HillPress. second-languagelearning: The influence of maturational state on wotff, A. B., & Brown, s. c. (1987). Demographicsof meningitis- the acquisition-ot English as a second language. Cognitive Psy' induced hearing impairment lmplications for immunization of chology,2t, 60-99. children againsfHemophilus Influenzae Type B. American Annals Johnson, J. S., & Newport, E. L (1991). Critical period efiects on of the Deaf, 132,2#O. universal properties of language: The status of subjacency in the acquisition of a second language. Cognition, 39,21*258. Krashen, S., Long, M., & Scarcella, R. (1979). Accounting for chitd-adutt difierences in second language rate and attainment. ReceivedMaY 15, 1992 TESOL Quarterly, 13, 107-1 14. AcceptedAugust 2, 1993 Lenneberg, E. H. (1964. Biologicalfoundations of language. New York John Wiley & Sons. Comrnunication Sci' Uddetl, S., & Johnson, R. (1989).American Sign Language:The Contact author: R. Mayberry, School of Hall, 1266 Pine phonologicalbase. Srgn l-anguage Studies, il' 19!.278. ences and Disorders, McGill University, Beatty Miyberry, R. l. (1992).The cognitivedevelopment of deaf children: Avenue West, Montreal,Quebec H3G 1A8, Canada. 36 ll58-l770 December1993 1270 Iournalof Speechand Heaing Resecrch

Appendix ASL StlmulusSentences (Given in EnglishTranslation) Deafclubs Theapproaching man who is deafdoesn't know American sign 5. when I was younger,I was very activein various 1. time any more. becausehe livesin England. that are locatedatl overthe city, but I haven'tany are muchmore likely than women to just sit 6. Yesterday,twas surprisedto bumpinto mytwo best childhood 2. On Sundays,men years. televisedsports all day long. friendswith whom I grewup andwhom I hadn'tseen for 10 and watch go the doctor 3. My boyfriend'sbest friend,who is standingover there,really 7. once whenI hada teniblecold that wouldn't away, datemy sister,but she won'thave anything to do with him. gave- me a newmedicine that cured my 1asaldripinstantangously' wantsto sincegas 4. Thatman's oldest daughter just hada babyboy, so he'savery 8. In the past,very few peoplerode bikes to work,but proudgrandfather right now. has gottenso expensive,scads of peopleride bikesto work now'