Co-speech gesture projection: Evidence from truth-value judgment and picture selection tasks

Abstract

Two main analyses have been proposed to explain how co-speech gestures interact with logical operators. According to the Supplemental analysis (Ebert & Ebert 2014), co-speech gestures have the same semantic status as appositive relative clauses. According to the Cosuppositional analysis (Schlenker To appear a; b), co-speech gestures trigger a particular kind of presupposition. The sentence "John will not use the stairs", produced with an UP gesture (finger pointed upwards) is argued to give rise to the conditional presupposition that if John were to use the stairs, he would use the stairs in an upwards trajectory. Both the Supplemental and Cosuppositional analyses predict that inferences triggered by co-speech gestures should project out of the scope of operators, but not quite in the same way. We present an experimental investigation of the projection properties of the inferences arising from the co-speech gestures UP and DOWN in six different linguistic environments (plain affirmative and negative sentences, modal sentences containing "might", and quantified sentences containing "each", "none", and "exactly one"). Applying a reading detection analysis (Cremers & Chemla 2017) to the responses of a Truth Value Judgment Task and a Picture Selection Task, we find evidence for existential projection of the gestural inferences in the scope of "each", "none", and "exactly one", and, to some degree, local accommodation of the inferences. These results can be derived by the Cosuppositional analysis, in combination with an analysis of presupposition projection such as Beaver (2001), which predicts existential projection out of quantified structures; on the other hand, both findings are difficult to reconcile with the Supplemental analysis. Our projection results bring gestural inferences and verbal presuppositions closer together, but a remaining puzzle is why in quantified structures we obtain existential rather than universal inferences (Chemla 2009), the latter being the more standard finding in the presuppositional literature (though see Tieu et al. 2016 for evidence of universal projection of the same gestural inferences).

Acceptability of at-issue co-speech gestures under contrastive focus

“…The previous studies don't take into account the role of focus in how co-speech gestures are interpreted. Thus, Tieu et al (2017; provide experimental data (truth-value judgements, picture selection tasks, inferential judgements) to support the claim that inferences contributed by co-speech gestures tend to project from a variety of embedded environments-significantly more so than contributions of control at-issue modifiers of the form like this gesture or alike:…”

“…It has been claimed in recent literature (Ebert & Ebert 2014;Tieu et al 2017;Schlenker 2018) that (1) gives rise to an inference that if John orders a beer, it will be large (i.e., John won't order a small beer). 2 In contrast, (2), a counterpart of (1) with an adjectival modifier, doesn't give rise to such an inference:…”

“…It is, however, also possible to attribute part of the variation observed to individual differences in behavior rather than grammar, in particular, how willing a given speaker is to ignore the contribution of co-speech gestures altogether when performing an acceptability judgement task. Tieu et al (2017;, for example, claim that the possibility that some participants were ignoring the gestures could explain some of their data. However, Tieu et al don't discuss individual variation in their data-it would be interesting to look at the individual patterns of judgements in their data to see if indeed that was a possibility.…”

Effects of linguistic context on the acceptability of co-speech gestures

“…Recently, this type of formal semantic/pragmatic analysis has been extended beyond language in a narrow sense to co-speech gesture (Ebert & Ebert 2014;Tieu et al 2017;Esipova 2018;Schlenker 2018). On the face of it, this is a natural extension, given that co-speech gestures are known to be prosodically integrated with spoken language and havebeenarguedtocontributetoaunifiedsemanticcontenttogetherwithspeech/sign (McNeill 1992;Kendon 2004;Goldin-Meadow & Brentari 2017).…”

Composition and projection of co-speech gestures

“…There is a general consensus in this literature that such gestures contribute projecting inferences by default (Ebert & Ebert 2014;Ebert 2017;Tieu et al 2017Tieu et al , 2018Schlenker 2018a,b), but there is no consensus on what mechanisms assure said projection. All of this literature, however, relies on an implicit or explicit assumption that the projection profile of co-speech gestures is uniquely determined by their co-speech status.…”