Summary of Flexible Processing and the Design of GrammarArticle: Ivan A. Sag and Thomas Wasow, Stanford UniversitySummary: Greg Shumway, Brigham Young University

Overview• Competence grammar informed by the incremental and

integrative nature of language processing• Grammar as a system of local monotonic constraints that

directly characterize the signs (i.e., the form-meaning correspondences) of a given language.

Processing: Sources of Info.• grammatical knowledge• discourse context• background world knowledge• social knowledge• knowledge of style / genre• gestures, paralinguistic information

The Big Sleep (1946)• VIVIAN: You like my father, don’t you?• MARLOWE: Mm-hum.• VIVIAN: Why don’t you stop?• MARLOWE: Remember I told you I was beginning to like

another one of the Sternwoods?• VIVIAN: I wish you’d show it.• MARLOWE: That should be awful easy.• VIVIAN: I like that. I’d like more ____. That’s even better.

• What does the underlined that mean?• What does the ellipsis after more mean?• Reference beyond the text: Vivian’s surname is Sternwood.

Casablanca (1942)• The noun Paris is used to denote a shared experience, not a

place

• “I wouldn’t bring up Paris if I were you...”

• Interpretation relies on a large quantity of shared background knowledge.

Other External Info. Sources• “I want you and you to come with me, while you stay here

with the kids.”• Visual and gestural information crucial for determining pronoun

referents• “Lin’s parents are only yea high, but he’s six foot three.”• Size indicator yea is meaningless without gesture

• “The police refused the students permission to demonstrate because they (feared / advocated) violence.”• Who does they refer to?

• “Having found the book on the (fable / table), I made sure to return it quickly to the library.”• How does the meaning of the preposition “on” change

depending on the object of the prepositional phrase?

Influence of Social Knowledge• In 2010, Casasanto conducted an experiment on social priming• Participants heard potentially ambiguous words that were

disambiguated by sentence context• Example: mast => [mæs] by final deletion of [t]• Such deletion occurs at a higher rate in African American speech

(Wolfram 1969)• Participants heard sentences like the following while viewing a

picture of a face, which they were told was the speaker.• The [mæs] probably lasted through the storm.• The [mæs] probably lasted an hour on Sunday.

• When asked whether the sentence made sense, participants responded significantly faster when the accompanying picture was of a black person.

Influence of Style and Genre• Newspaper headlines often employ the structure of a “garden

path,” i.e., N-V-PP-VP (where V could be a past participle or a passive participle)• US Tourists Seized in Egypt’s Sinai Released• Peoria Man Arrested in Fatal Stabbing Is Released from Jail• Activist Detained in Mideast Speaks• Baltimore Man Detained in Guantanamo Formally Charged• 2 Arrested After Band’s Protest at Moscow Cathedral to Remain

Jailed• All of these have a hard-to-parse telegraphic style, but readers

who encounter them often process them with little difficulty.

Complex Language Processing• Involves many diverse sources of information:• grammatical knowledge• discourse context• gestures and visual information• general world knowledge• social knowledge• knowledge of style and genre

Three Questions• How does integrative processing take place?• What is the architecture of the processor (or processors)?• What does processing tell us about the design of grammar?

Casablanca• Rick: I congratulate you ___.• Victor: What for___?• Rick: ___Your work.• Victor: I try___.• Rick: We all try___. You succeed___.

• Speakers must be able to infer the missing parts of the other person’s utterances.• They must quickly select between many alternative meanings

Disambiguation• Lexical• bank, can, will, duck, to/two/too,etc.

• Structural• I found the message in the book.• I forgot how good beer tastes.

• Combinations of Lexical and Structural• I saw her duck.• That creature has two legs and flies.

Division of Labor proposals• Grammar provides argument variables (for pronouns, ellipsis,

names, etc.). The processor assigns values to variables incrementally.

• Grammar proposes disjunctions in certain cases (e.g., lexical or structural ambiguity). The processor simplifies these disjunctions as quickly as possible.

• Grammar provides underspecified semantic representations (for scope, polysemy, etc.). The processor refines these representations monotonically.

Underspecification• Underspecified representations• “Kelly showed every photo to a critic last month.” (How many

critics?)• “Unfortunately, the book didn’t sell.” (physical or textual object?)

• torn pages (physical)• poor reviews (textual)

Findings• Listeners process utterances incrementally• Don’t have to hear a whole sentence before constructing

interpretation.• Experimental Evidence• Psycholinguistic literature over the past 30 years indicates that

listeners are remarkably fast at resolving ambiguity and under-specification.

• Resolution proceeds incrementally• Listeners begin determining intended interpretations of utterances

as soon as they are uttered• They don’t wait for grammatical analysis of subsequent material

Proposal: Realistic Grammar• Constraint-Based Architecture• constraints are unordered and input-driven• grammars should be formulated in a process-neutral way

• Surface-oriented grammatical analysis• Experimental work by Pickering and Branigan (2012) supports “a

single, ‘shallow’ surface syntactic representation• Occam’s razor favors a theory with only one syntactic level

• Sign-based grammar• Linguistic expressions relate forms (sounds / symbols) with

meanings.

(Realistic Grammar cont.)• Strong lexicalism• Words are information-rich (knowing one involves a great deal)• The lexicon should represent word groupings and categories in

terms of: (1) what they mean, (2) what they combine with, and (3) their inflectional properties.

• Representational underspecification• The processor builds partial representations, incorporating

information that is available at each moment, but remains uncommitted where decisive information is not yet available.

• Semantic representations can be built up incrementally simply by specifying previously unspecified information.

Sign-Based Construction Gmr.• The meanings of most words can best be understood on the

basis of a semantic frame• description of a type of event, relation, or entity and the

participants in it• Frames are modeled as typed feature structures• Lexical meanings are hierarchically organized

Sign-Based Construction Gmr.

Conclusions about Processing• The Language Processing System proposed in this paper:• is situated and discourse-driven• is incremental and flexible• is semantically and pragmatically modulated• is multimodal and cue sensitive• is distance-locality sensitive• is constrained by frequencies, yet open to priming• keeps fillers active• has limited non-determinism

• “By connecting grammar more tightly with work on processing, we can motivate the high-level design of grammar, draw conclusions about the particulars of individual grammars, and provide better sources of explanation for many linguistic phenomena.”

- Ivan A. Sag

Thank you!• Sag, Ivan A. Flexible Processing and the Design of Grammar.

Journal of Psycholinguistic Research (2014). Volume 44, Issue 1