( R e)construing Meaning in NLP (2020)

Abstract: Human speakers have an extensive toolkit of ways to express themselves. In this paper, we engage with an idea largely absent from discussions of meaning in natural language understanding—namely, that the way something is expressed reflects different ways of conceptualizing or construing the information being conveyed. We first define this phenomenon more precisely, drawing on considerable prior work in theoretical cognitive semantics and psycholinguistics. We then survey some dimensions of construed meaning and show how insights from construal could inform theoretical and practical work in NLP.

## introduction natural language is a versatile tool for allowing humans to express all manner of communicative intents, from simple descriptions of the entities and situations in their direct experience to elaborate rhetorical flights of fancy. many nlp applications, such as information extraction, question answering, summarization, and dialogue systems, have restricted their scope to what one might call objective information content-relatively uncontroversial facts that systems can infer from an utterance, store in a database and reason about. while it is tempting to equate such information with the meaning of an utterance, a large body of literature in linguistics and psycholinguistics argues that an utterance conveys much more than a simple set of facts: it carries with it a halo of intimations arising from the speaker's choices, including considerations of perspective, emphasis, and framing. that is, linguistic choices subtly color meaning; far from merely conveying objective facts, they reflect how speakers conceptualize meaning and affect listeners' interpretations in predictable ways. take, for example, this metaphor-rich portrayal of a newborn as a tyrant over her parental subjects: this report of new parenthood describes a major life change along with everyday caregiver routines, but its emphasis is on the parents' experience of being suppressed (under) and controlled (grip) by a creature who is cast, variously, as a tyrant (regime), a bird (squawk), and a relentless machine (sleepinput-output cycles, iron grip)-albeit a (subjectively) adorable one. the power of linguistic choices to shape understanding is also evident in more mundane @xcite examples: jerry sold a car to chuck. jerry paid chuck for the car. b. i work at microsoft. i work for microsoft. c. the statue stands in the plaza. the statue is standing in the plaza. each set includes sentences that convey roughly the same facts-i.e. they could describe the same scenario-but nonetheless differ in various respects. the familiar framing differences between buy/sell/ pay (2a) focus attention on different participants and subevents in a commercial transaction. (2b) involves a subtler difference in emphasis, where the choice of at highlights the location of the work, while for evokes how that work benefits the employer. grammatical marking can also shift event connotations, as illustrated by the stative vs. temporary contrast in (2c). such distinctions illustrate the general phenomenon of construal, which we claim has been neglected in nlp. we believe that a proper recog-nition of construal would provide a unified framework for addressing a wide range of issues involving meaning and linguistic variation, opening the way to systems that more closely approximate (actually) natural language. this paper surveys the theoretical and empirical landscape related to construal phenomena and makes the case for its relevance to nlp. after clarifying the terms adopted here ( §2), we lay out a few key dimensions of construed meaning ( §3) and then elaborate on some mechanisms of construal ( §4). a trio of case studies illustrate how different types of construal can challenge nlp systems ( §5). we end with some conclusions and suggestions for how to begin addressing these challenges ( §6). ## meaning and construal our view of construal and its close companion meaning is rooted in both frame-based and cognitive semantic traditions. the notion that words and other linguistic units evoke background scenes along with specific perspectives on those scenes is captured by @xcite slogan, mean-ings are relativized to scenes. this idea has deeper consequences than merely assigning different semantic roles to examples like (2a). as @xcite observes, "any given situation can be viewed in multiple if not infinitely many ways. starting from the same basic conceptual content. . . we can form an endless variety of specific conceptions by making alternate choices in regard to the many dimensions of construal." this view of linguistic meaning-which we might call inherently multivalent-is more flexible than in many theoretical and computational treatments, particularly truth-conditional approaches that liken meanings to facts in a database. the visual domain offers a more informative analog: a photographic or artistic rendering of a scene can vary in vantage point, viewing distance, objects in sight or in focus, color and lighting choices, etc. @xcite . context matters, too: a painting hanging on a preschool wall may be received differently if displayed in a museum. just as there is no one objective, context-independent depiction of a scene, there are many valid ways to present an idea through language. we thus extend fillmore's slogan to include all kinds of conceptual content (beyond scenes); the broader communicative context; and the effect of choices made as part of the construal process: meanings are relativized to content, context and construal. below we elaborate on how each of these interrelated factors affects construed meaning. ## dimensions of construed meaning several (partial) taxonomies of construal dimensions have been proposed in the cognitive linguistics literature @xcite @xcite @xcite ; see @xcite for an overview. we will not attempt to reconcile their many differences in terminology and organization, but instead present selected dimensions most relevant for nlp. ## construal in action how might construal work in practice? we have emphasized so far the flexibility afforded by the dimensions in §3. but we must also explain why some words and concepts make easier bedfellows than others. this section presents a thumbnail sketch of how the construal process copes with apparent mismatches, where it is the collective constraints of the input structures that guide the search for coherence. we focus on comprehension (similar processes apply in production), and assume some mechanism for proposing interpretations consisting of a set of conceptual structures and associated compatibility constraints. compatibility constraints are analogous to various kinds of binding constraints proposed in the literature (variable binding, rolefiller bindings, unification bindings, and the like): they are indicators that two structures should be conceptualized as a single unit. but compatibility is softer and more permissive than identity or typecompatibility, in that it can also be satisfied with the help of construal operations. some operations effect relatively subtle shifts in meaning; others have more dramatic effects, including changes to truth-conditional aspects of meaning. below we illustrate how some example linguistic phenomena fit into the sketch just presented and mention connections to prior lines of work. count/mass coercion. english nouns are flexible in their count/mass status (see §3.4). atypical marking for number or definiteness can cause a shift, or coercion, in boundedness: plural or indefinite marking on mass nouns (a lemonade, two lemonades) yields a bounded interpretation (cups or bottles of lemonade). conversely, count nouns with no determiner are coerced to an undifferentiated mass, via a phenomenon known as grinding ("there was mosquito all over the windshield") @xcite @xcite . here we see evidence of the outsize influence of tiny grammatical markers on manipulating lexical defaults in the construal process. aspectual composition. aspect is a prime arena for studying how multiple factors conspire to shape event construal. verbs are associated with default aspectual classes that can be coerced under pressure from conflicting cues, where details of event structure systematically constrain possible coercions and their inferential consequences @xcite . in fact, aspectual coercion can be reanalyzed in terms of construal dimensions. for example, durative modifiers (e.g. for an hour) prefer to combine with atelic processes (lacking a defined endpoint, as in 3a) on which to impose a bound (analogous to count/mass coercion) and duration. combination with any other aspectual class triggers different operations to satisfy that preference: a single sneeze, being a discrete event unlikely to last an hour, undergoes iteration into a series of sneezes (3b), illustrating a change in plexity ( §3.4); while the book-reading in in ( 3c ) is simply viewed as unfinished (cf. "he read the book"). the departure in (3d) is a discrete event, but unlike sneezing, it also results in a state change that is reversible and therefore boundable (cf. the iterative reading of "he broke the glass for an hour", the non-permanent reading of 2c). its coercion thus features multiple operations: a prominence shift to profile the result state of being gone; and then a bounding that also reverses state, implying a return @xcite . constructional coercion. the flagship example cited in the construction grammar literature (4a) has also been analyzed as a kind of coercion, serving to resolve conflicts between lexical and grammatical meaning @xcite : here, the verb sneeze, though not typically transitive or causal, appears in a caused motion argument structure construction, which pairs obliquetransitive syntax with a caused motion scene. the resulting conflict between its conventional meaning and its putative causal role is resolvable, however, by a commonsense inference that sneezing expels air, which can plausibly cause the napkin's motion (cf. @xcite . this coercion, also described as role fusion, differs from the previous examples in manipulating the prominence of a latent component of meaning. coercion doesn't always succeed, however: presumably sneezing could only move a boulder with contextual support, and sleeping has a less plausibly forceful reading. in fact, construal depends on the interaction of many factors, including degree of conventionality (where push and blow are prototypical caused motion verbs), embodied and world knowledge (the relative forces of sneeze and sleep to napkin weight), and context. 5 there is extensive psycholinguistic evidence of constructional coercion and the many factors influencing ease of construal (see @xcite for reviews). some of these phenomena have been analyzed within computational implementations of construction grammar @xcite @xcite @xcite @xcite , and have also been incorporated in corpus annotation schemes @xcite @xcite . metonymy and metaphor. metonymy and metaphor are associated with semantic mismatches 5 a related theory is @xcite semantic proto-roles account, which links the grammatical subject/object asymmetry to two clusters of semantic features that are more agent-like (e.g., animacy) or patient-like (e.g., affectedness), respectively; associations between these proto-roles and grammatical subjects and objects are attested in comprehension @xcite and have been investigated computationally @xcite . first, the modifiers tiny and iron expect a physical entity, but grip is a (nominalized) action. this conflict triggers a profile shift (prominence) to the grip's effector (a hand), effectively licensing a metonymy. a further conflict arises between the hand and its description as iron (unlikely to be literal unless the protagonist is of robotic lineage). a structural alignment (metaphor) then maps the iron's strength to the grip's force, which in turn maps to the degree of dictatorial control. 6 we observe that multiple construal operations can occur in sequence; that a conceptual or linguistic element may afford more than one construal within the same analysis (grip as both a hand and metaphorical control); and that aspects of common sense, world knowledge, and culture (though not the focus of the present work) inevitably constrain construal options. ## case studies we turn to a few illustrations of how the pervasive effects of construal can arise in applied settings. ## discussion throughout this paper, we have emphasized the flexible and multivalent nature of linguistic meaning, as evidenced by the construal phenomena described here. the effects of construal are ubiquitous: from conventional to creative language use, through morphemes and metaphors. indeed, even the smallest forms can, like tiny tyrants, exert a transformative force on their surroundings, inducing anything from a subtle shift in emphasis to a radical reconceptualization. as illustrated in §5, this flexibility of language use poses a challenge for nlp practitioners. yet crucially-and fortunately-construal is not random: variations in linguistic form correspond systematically to differences in construal. the dimensions of construal and their associated operations ( §3 and §4) offer principled constraints that render the search for coherence more tractable. how, then, should we proceed? our goal is for construal dimensions such as those highlighted in §3 to be incorporated into any research program aspiring to human-level linguistic behavior. below, we describe several concrete recommendations for how to do this. more meaningful metrics. taking construal seriously means rethinking how nlp tasks are designed and evaluated. construal dimensions can provide a rubric for assessing tasks, datasets, and meaning representations @xcite for which meaningful distinctions they make or require. (e.g.: does it capture the level of reso-lution at which entities and events are described? does it represent metaphor? is it sensitive to the prominence of different event participants?) such questions might also help guard against unintended biases like those recently found in nlp evaluations and systems (e.g., @xcite . popular nlu benchmarks (like superglue; @xcite should be critically examined for potential construal biases, and contrasts should be introduced deliberately to probe whether systems are modeling lexical choices, grammatical choices, and meaning in the desired way @xcite @xcite . as a broader suggestion, datasets should move away from a one-size-fits-all attitude based on gold annotations. ideally, evaluation metrics should take into account not only partial structure matches, but also similarity to alternate construals. ## conclusion as the saying goes, the camera doesn't lie-but it may tell us only a version of the truth. the same goes for language. some of the phenomena we have described may seem, at first glance, either too subtle to bother with or too daunting to tackle. but we believe it is both timely and necessary, as language technologies grow in scope and prominence, to seek a more robust treatment of meaning. we hope that a deeper appreciation of the role of construal in language use will spur progress toward systems that more closely approximate human linguistic intelligence. verb constructions. in asaf bachrach, isabelle roy, and linnaea stockall, editors, structuring the argument, pages 61-80. john benjamins, amsterdam. eva wittenberg and roger levy. 2017. if you want a quick kiss, make it count: how choice of syntactic construction affects event construal. journal of memory and language, 94:254-271. semih yagcioglu, aykut erdem, erkut erdem, and nazli ikizler-cinbis. 2018. recipeqa: a challenge dataset for multimodal comprehension of cooking recipes. in proc. of emnlp, pages 1358-1368, brussels, belgium.