lundi 17 septembre 2012

Séminaires Edward Gibson

Linguistique expérimentale, théorie de l'information, ça n'est pas vraiment du TAL, mais cela devrait intéresser les linguistes-informaticiens, et c'est une grande chance que de pouvoir bénéficier de la présence de ce grand spécialiste, invité par l'EFL et LLF pendant ce semestre.

Le Labex EFL est heureux d'annoncer le cours de Edward Gibson, MIT, Brain and Cognitive Sciences, qui commence lundi, 17 septembre, au LLF, Paris Diderot, Salle 4C92.

Cours tous les lundis du 17 septembre au 10 décembre, 16-18 h
175 rue du Chevaleret, 4e étage, salle 4C92


The proposed seminar is inspired by Shannon's (1948) seminal work on information theory and will focus on communicative properties of language representations and processing. Three broad questions will be addressed: 1. How do communicative pressures shape the lexicon? 2. How do communicative pressures shape the syntax of languages? 3. How do communicative properties of language affect interpretation of the linguistic signal? In the first section of the course I will discuss Zipf's (1949) original ideas on the relationship between word length and frequency and recent findings that extend those ideas and show that word length is better explained by how predictable a word is in the context in which it appears than by word frequency. I will then talk about lexical ambiguity and present evidence that ambiguity is not a weakness of the language system, as has been argued by e.g., Chomsky. Instead, ambiguity is a desirable feature of any communication system because it allows for a more efficient lexicon. In particular, the same 'easy' (e.g., short or easily pronounceable) words can be reused in the language, referring to different things, because context can and does robustly disambiguate the intended meaning. I will also discuss ambiguity in the context of word learning.

In the second section of the course I will focus on language structure. A recent paradigm, in which participants are asked to gesture the meanings of simple events (Goldin-Meadow et al., 2008), has been shown to reflect word-order preferences somewhat independent of native language and is thus promising for revealing fundamental properties of our communication system and perhaps shedding light on how different word orders arose in the course of language evolution. For example, when shown a picture or animation of a boy kicking a ball, speakers of languages with either a subject-verb-object (SVO) order or a subject-object-verb (SOV) order gesture the event as subject-object-verb (i.e., 'boy', 'ball', 'kick'). This finding has been interpreted as evidence for SOV order being somehow fundamental or ?base? in how we think about events. Critically, however, we have shown that when asked to gesture meanings of 'reversible' events (e.g., a boy pushing a girl), where either entity can be the agent or the patient of the action, the gesture sequences shift to the SVO order, across languages. This finding fits well with the idea that communication takes place over a noisy channel, where the signal may get corrupted in some way. The use of SVO gesture sequences for reversible events makes the meaning more robust to noise thus maximizing the chances of the comprehender recovering the intended meaning. I will further connect these experimental findings to typological patterns across languages. The noisy-channel hypothesis makes several attested predictions about cross-linguistic variation, such as prevalence of casemarking in SOV languages, and lack of case-marking in SVO languages, suggesting that a shift from SOV to SVO word order makes the language sufficiently robust to noise. However, if a language keeps its base SOV word order, then another 'device' is needed to make the signal more robust to noise, and case-marking is one way of marking the agent and patient of an event. In the third section of the course I will talk about how communicative properties of the language system affect the interpretation of the linguistic signal. Until recently, it has been assumed that the input to the sentence comprehension mechanism is an error-free sequence of words. However, given that noise (speaker errors, perception errors, or noise in the environment) can corrupt the linguistic signal, as discussed above, the human sentence comprehension mechanism is plausibly adapted to process sentences that contain errors. A noisy-channel model predicts that the interpretation of a corrupted linguistic signal will depend on how easily recoverable the plausibly intended signal is. If the comprehender can easily explain how the original signal got corrupted, then s/he will rely on semantic cues for interpretation. If, on the other hand, there is no clear explanation for how the signal got corrupted, then the comprehender is predicted to more closely follow the actual syntactic form of the utterance in deriving an interpretation. These predictions are in contrast to those of some earlier models, according to which the final interpretation is always determined by the syntax of an utterance (cf. MacWhinney et al., 1984), even though meaning may guide initial interpretation in the face of temporary syntactic ambiguity. I will discuss several recent sets of findings in sentence comprehension that provide support for the noisy-channel model as well as re-interpret some classical findings in the context of this model.

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