1Psych 56L/ Ling 51:Acquisition of LanguageLecture 5Biological Bases of Language IIIAnnouncementsReview questions for biological basis of language availableHomework 1 assigned, due next Monday (10/20/08) in class.Class Reader:Jacquece Fradue, [email protected] and Other SpeciesLanguage and Other SpeciesAre we special among the animal species?What are other species capable of?Could language have evolved gradually?2Communication SystemsHuman language does enable communication, but it hasseveral features that separate it from other animalcommunication systems:reference: symbols stand for things in the worldsyntax: productive system for combining symbols to expressnew meaningsintentionality: speakers use language for the purpose ofcommunicating with othersPrimate CommunicationVervet monkeysPredator alarm calls:“leopard” = run to the trees“eagle” = look up, run into the bushes“snake” = stand up on hind legs & lookaroundNo evidence for complex combinatorial system or thatmonkeys produce calls with the intent to modify the mentalstate of their listener.Primate CommunicationVervet monkeysWhat they can’t say:“What a large eagle up in the sky overthere! We’d better take cover. C’mon!”“I doubt there are any leopards aroundhere. The field looks pretty clear.”“Did you see that whopping big snakeyesterday? It was so scary!”Bee CommunicationHoney BeesDance to communicate the location offood (nectar)Can indicate: nearby vs. far, direction,richness of the food source (danceharder for the good stuff)Though bees can create novel messages, they’re alwaysabout the location of food.3Bee Communication‘deciphered’ by Karl von Frisch, 1919 & onwardUnder 50 m awayOver 50 m away:encodes distance& direction - isencoding of 2Dspace (a bee’s“mental map”)Bee CommunicationHoney BeesWhat bees can’t communicate:“Have you seen the flowers in the nextfield over? They totally rock. I’ve neverseen such brilliant colors.”“This hive is lookin’ gooooood lately.”Bird CommunicationSongbirdsMales use songs to attract andacquire mates. In many species,the development of the songrequires exposure to adult birdswho model the song.Bird CommunicationSongbirdsNote: even though there is alearned part and a genetic part, westill classify birdsong as an instinct.4Bird CommunicationSparrow Song song callSong is highly structured - notes, syllables, phrasesBird CommunicationVariation in SongBird 1Bird 2Bird CommunicationSongbird communication is thought to be similar to human childrenneeding exposure to adult language. Both human language andbirdsong: (1) have early stages prior to the appearance of the adult form(babbling vs. subsong) (2) require the babies to be able to hear their own productions (3) have sensitive periods (4) are lateralized in the left hemisphereLearning Human LanguageJust because other animals’ communication systems aren’t ascomplex as human language, does that mean that they’reincapable of learning human language (reference, syntax,intentional communication)?5Alex the ParrotGrey parrot, born 1976, died 2007 Trained by Dr Irene Pepperberg (U. Arizona) since 1977 Impressive ability to speak/understand…for a parrothttp://www.youtube.com/watch?v=R6KvPN_Wt8IAlex’s language• Speech sounded remarkably accurate…produced very differently from humans• Knew names of about 150 objects plus some fixedexpressions• Answered simple questions about objects (e.g. aboutsize, color, material)• Required immense amounts of trainingTeaching chimpanzeesTeaching chimpanzees to speak didn’t work out very well1930s: Gua, raised in a human home and treated like humaninfant along with the couple’s son- motor skills surpassed child’s, but never learned to speakwhile the child did1940s and 50s: Viki, raised in a human home and activelytaught to produce words- by 6, Viki could say “mama”, “papa”, “cup”, and “up”Problem: Chimpanzees have a vocal tract that makesspeech production essentially impossible.Teaching chimpanzeesTeaching chimps to sign using ASL1960s: Washoe, lived in trailer in backyard, people alwayscommunicated via ASL, taught by molding hands into theappropriate signs- learned to produce 132 signs after 4 years, correctlylabel a variety of objects and sign small expressions like“more fruit”, “Washoe sorry”, and “Please tickle”6Teaching chimpanzeesTeaching chimps to sign using ASL1979: Nim Chimpsky, raised in private home, taught signs byhaving hands molded into them- learned 100 signs and produced some combinationsBut combinations produced are very different from those of ahuman child - very repetitive, no additional complexity:2-sign 3-sign 4-sign“eat drink” “eat me Nim” “eat drink eat drink”“tickle me” “me Nim eat” “play me Nim play”Teaching chimpanzeesTeaching chimps to sign using ASLNim’s longest utterance: “give orange me give eat orange meeat orange give me eat orange give me you”Also, all Nim’s sign combinations were imitations of histeachers - no novel combinations, unlike human children.No symbolic reference:“For Nim, meaning seemed to have no role outside of thespecific association between a form and its referent thathad been explicitly taught to him….for Nim, signs did notrefer; he did not have words - signs, or names - for things.”- Laura Petitto, one of Nim’s teachers, 1988Teaching bonobosBonobos (pygmy chimpanzees)vocalize in communication morefrequently than common chimps do.1981: adult bonobo Matata instructed with an artificiallanguage and utterly failedHowever, her infant bonobo Kanzi - who wasn’t explicitlyinstructed in anything - learned the artificial language andalso to understand some spoken English.http://www.greatapetrust.org/media/video-bonobo-kanzi.phpTeaching bonobosDid Kanzi have reference?“strawberry” = “I want to go to the placewhere strawberries are found”, “Iwant a strawberry to eat”, “There’s apicture of strawberries”, …Kanzi’s spoken English: comparable to a 2-yr old child’sperformance (but a 2-year old’s syntactic knowledge is fairlylimited)Also, Kanzi was 8 years old when he was tested, and wasunlikely to improve his performance any further withage….unlike human children.7So what’s the problem?Not a lack of intelligence - chimpanzeesare highly intelligent.One answer: language is an expression of a domain-specificmental faculty that humans have and other primates do