19 May 2007

Michael Tomasello despre originea comunicarii

Michael Tomasello e unul dintre cei mai meseriasi oameni de stiinta contemporani. El si echipa lui de la Institutul Max Planck de Antropologie Evolutionista din Leipzig fac experimente (in special) cu cimpanzei, copii mici, si caini incercand sa descopere in ce anume exact consta diferenta dintre oameni si restul animalelor. Ideea lor este ca probabil exista o singura diferenta intre noi si animale care a generat apoi un efect de avalansa. Principalul lucru care ne diferentiaza de celelalte animale este ca noi avem o cultura care evolueaza - multe dintre lucrurile care sunt descoperite sau inventate nu se pierd, iar generatiile ulterioare nu pleaca de la zero, ci construiesc pe bazele lucrurilor deja cunoscute. Asta e ceea ce a facut posibila raspandirea atat de spectaculoasa a omului, dominarea intregii planete si transformarea mediului in care traim intr-unul aproape in intregime artificial. Dintr-un motiv sau altul, alte animale, nici macar cimpanzeii, nu sunt capabili de o evolutie culturala similara, motiv pentru care societatile de animale (de exemplu felul in care sunt organizate haitele de lupi sau grupurile de cimpanzei) raman aproape neschimbate milioane de ani. In 1999 Tomasello a scris o carte, The Cultural Origin of Human Cognition, in care sustinea ca diferenta principala dintre om si cimpanzei e ca omul reuseste sa-i inteleaga pe ceilalti oameni drept niste fiinte ca urmaresc scopuri si selecteaza mijloacele care li se par cele mai eficiente pentru a-si atinge scopurile alese. Cele mai multe animale sunt intr-adevar incapabile sa inteleaga faptul ca alte animale au scopuri - si nici nu sunt in stare sa se inteleaga pe ele insele ca urmand scopuri. Acesta este motivul pentru care de pilda atunci cand ii arati unui caine ceva cu degetul el nu se uita la ce ii arati, ci la degetul tau - cainele nu intelege ca iti folosesti degetul ca un mijloc pentru a-i indica ceva. Cele mai multe animale inteleg lumea si tot ce e in ea in termeni pur cauzali - adica o inteleg presupunand ca ceea ce s-a intamplat in trecut se va repeta in viitor. De aceea animalele nu sunt prea creative, dupa standardele noastre. A crea ceva nou inseamna fie a folosi resursele prezente pentru a obtine altceva decat pana acum (a dori sa ajungi in alt loc decat au ajuns ceilalti), fie a crea noi mijloace (eventual mai eficiente) pentru a obtine ceva. Aceasta abilitate de a intelege diferenta dintre scopuri si mijloace este esentiala insa nu numai pentru creativitate, ci si pentru capacitatea de a invata. Atunci cand inveti ceva de la altcineva inveti cum se face ceva - pentru asta trebuie sa intelegi diferenta dintre ce urmareste ala sa faca si mijloacele pe care le adopta. Experimente cu cimpanzei si copii mici arata ca cimpanzeii invata ce anume sa faca si in mare masura descopera singuri metodele, in timp ce copiii invata metoda care le este aratata pentru a face ceva. Copiii tind sa se tina cu strictete de metoda care le este arata chiar si atunci cand acelasi rezultat poate fi obtinut mult mai simplu altfel (din acest punct de vedere cimpanzeii par mai inteligenti!). Anul trecut insa, insusi grupul lui Tomasello a reusit sa arate ca cimpanzeii sunt si ei capabili sa inteleaga actiunile altor animale in termeni de scopuri si mijloace. Ei au descoperit asta cand unul dintre cercetatorii de la Institutul Max Planck intindea rufele la uscat si i-a scapat un carlig de prins rufele. Spre uimirea lor, un cimpanzeu care a vazut asta s-a dus din proprie initiativa sa-i dea carligul. Cand insa au aruncat carligul pe jos, cimpanzeul a sesizat diferenta dintre un gest intentionat si unul involuntar, si nu s-a mai oferit sa ajute. Alte experimente au aratat apoi ca abilitatea de a intelege scopuri nu este de fapt ceva atat de dificil pentru cimpanzei si ca fac asta in mod curent. Intrebarea a fost atunci din ce cauza nu au si cimpanzeii o evolutie culturala similara cu a noastra? Este clar ca diferenta dintre noi si verii nostri cei mai apropiati este mai subtila. Anul trecut Tomasello a primit premiul Jean Nicod si a tinut o serie de patru lectii (pe care le puteti vedea aici) despre acest subiect. Se pare ca ceea ce ne face umani nu este atat abilitatea de a intelege ca altii au scopuri, cat abilitatea de a ne angaja in activitati de colaborare in vederea atingerii unui scop comun (ceea ce este numit "shared intentionality"). Acest gen de activitate este mai complicat pentru ca presupune patru termeni. Spre deosebire de "X foloseste M pentru a atinge scopul S", colaborarea este de forma "X si Y folosesc M pentru ca impreuna sa obtina S". Facand tot felul de experimente, cercetatorii au fost mirati sa constate ca cimpanzeii nu reusesc sa inteleaga ideea ca altcineva este altruist fata de ei - cu toate ca, asa cum s-a intamplat in cazul cu carligul, ei insisi sunt uneori altruisti! Astfel, ei reusesc sa inteleaga ce vrea altcineva numai in situatii conflictuale! De pilda cercetatorii au facut urmatorul experiment: Intr-o galeata erau niste banane. Daca experimentatorul se indrepta spre galeata, cimpanzeul ghicea ca s-ar putea sa fie ceva in galeata; insa daca experimentatorul numai arata spre galeata (spre deosebire de caini, cimpanzeii inteleg cand le arati ceva cu degetul), cimpanzeul nu intelegea - vedea doar galeata si nu se gandea ca poate vrei sa-i zici ceva util. Altfel spus, cimpanzeii inteleg gestul de a arata cu degetul numai la modul indicativ (ca indiciu ca vrei ceva de la ei), nu si declarativ (informativ: ca indiciu ca vrei sa-i arati ceva util pentru ei). Asta pare a fi explicatia pentru care cimpanzeii nu reusesc sa se angajeze in activitati de colaborare in vederea unui scop comun. Iata descrierea prelegerilor, Origins of Human Communication:

Lecture 1: The Intentional Communication of Great Apes

Apes communicate with conspecifics most flexibly in the gestural domain, including adapting to the attentional state of the recipient. They use both intention movements (abbreviations of social actions that become communicative within a specific interactive context) and attention getters (actions that gain the attention of others to the self in a wide variety of contexts). All of these are basically dyadic - aimed at regulating the social interaction directly - not triadic in the sense of referring to external entities. They are also all basically "competitive" - aimed at getting the signaler what she wants - not co-operative in the sense of sharing psychological states. Interestingly, when interacting with humans many apes do learn to "point" to things they want triadically. But these "points" are action imperatives only; they are not co-operative in the human sense (and may not even be truly referential), as evidenced by the fact that these pointing apes still do not understand when humans point for them informatively. [handout] Lecture 2: The Co-operative Communication of Human Beings In contrast to our nearest primate relatives, human beings communicate with one another co-operatively. This co-operative structure pervades all aspects of the communicative exchange. Thus, human communication depends fundamentally on: (1) a joint attentional (or intersubjective) frame that provides the common ground necessary for reference; (2) the mutual manifestness of the communicative act itself, which generates both relevance inferences and interpersonal obligations; (3) the co-operative motives to help and to share experience with others (even if embedded within a selfish, deceptive motive); and (4) the ability to collaborate with others in joint activities, specifically to ensure that the receiver comprehends the sender's message as intended. The communicative activities of other animal species have little resembling this same co-operative structure. Human co-operative communication emanates evolutionarily from an adaptation for shared intentionality in general, as manifest in many other human cultural activities. Linguistic communication has this same co-operative structure, but adds, in addition, the perspective-taking inherent in contrastive linguistic symbols. [handout] Lecture 3: The Ontogenetic Emergence of Shared Intentionality The human adaptation for shared intentionality emerges ontogenetically at around the first birthday as two developmental pathways come together: (1) the general primate social-cognitive ability to understanding the goals and perceptions of others (and perhaps the intentions and attention of others); and (2) the uniquely human skills and motivations for sharing psychological states with others. As these two strands come together, human infants become able to create shared goals and intentions with others in joint action, and also to engage in various kinds of joint attentional activities, which create the ability to understand multiple perspectives on a common entity. The difference between humans and apes can be most clearly seen when their behavior is compared in situations involving helping (which do not involve full-blown shared intentionality, and in which they differ only a little) and situations involving true co-operation and shared intentions (in which they differ more profoundly). This same basic difference emerges when humans and apes are compared in the comprehension of communicative intentions (e.g., as expressed in both deictic and iconic gestures): human infants understand co-operative communicative intentions prelinguistically, whereas apes do not understand these at all - but rather understand the (social) intentions of others most readily in competition. [handout] Lecture 4: The Ontogenetic emergence of Co-operative Communication

Infants begin expressing their communicative intentions also at around the first birthday. In addition to co-operative requests (expressions of desire that helpful others are supposed to respond to helpfully), infants also communicate prelinguistically for two other basic motives: (1) to help others by providing them with needed information (informing); and (2) to simply share interest and attention with others to outside events and activities declaratively. They also, on occasion, gesture for others iconically [deictic gestures being triadic analogues of ape attention-getters and iconic gestures being triadic analogues of ape intention movements]. A series of experiments suggests that these early communicative acts involve full-blown shared intentionality, including participation in joint attentional (intersubjective) frames with distinct perspectives, participation in joint activities with shared goals and intentions, and the comprehension of co-operative communicative intentions. Less certain is how infants acquire these skills (imitation?ritualization?), and whether infants' comprehension of communicative intentions is fully Gricean (she intends that I know that she intends that we share attention to X). Studies of how infants acquire their earliest skills of linguistic communication in discourse help to resolve some of these outstanding issues. [handout]