Goldin-Meadow & Brentari (G-M&B) write that “sign should be compared with speech-plus-gesture, not speech alone” (sect. 7.1). We explain, first, why recent studies of sign language semantics converge on the same conclusion and, second, how semantic methods could offer a typology of iconic enrichments in both modalities (see Schlenker Reference Schlenker2016).

An expression (in any modality) may be termed iconic if there exists a structure-preserving map between its form and its denotation. In (1)a, the length of the talk is an increasing function of the length of the vowel. In the American Sign Language (ASL) example in (1)b, the outcome of the growth is an increasing function of the maximal distance between the two hands realizing the verb GROW.

1. 1.

   1. a. The talk was long / loooooong. (cf. Okrent Reference Okrent, Meier, Quinto-Pozos and Cormier2002)

   2. b. POSS-1 GROUP GROW- / GROW- / GROW-.

“My group has been growing a bit / a medium amount / a lot.” (ASL; video 8, 263; see Schlenker et al. Reference Schlenker, Lamberton and Santoro2013)

Recent work in sign language semantics has argued for two claims (Schlenker, Reference Schlenkerforthcoming).

Logical visibility. When iconic phenomena are disregarded, speech and sign share the same “logical spine,” including in cases where sign language makes visible the “Logical Forms” of spoken language sentences – for instance, by making overt use of logical indices realized as “loci,” whereas indices are mostly covert in spoken languages (Lillo-Martin & Klima Reference Lillo-Martin, Klima, Fischer and Siple1990).

Iconicity. Sign language makes use of rich iconic resources, including at its logical core. For instance, sign language loci were argued in recent research to be both logical variables and simplified representations of what they denote (see Schlenker et al. Reference Schlenker, Lamberton and Santoro2013 and, for some sources, see Liddell Reference Liddell2003 and Kegl Reference Kegl1977/2004).

This could lead to two conclusions.

One conclusion is that spoken language semantics is (along some dimensions) a “simplified,” iconically defective version of sign language semantics – simply because the iconic potential of the vocal stream is so limited.

Alternatively, it may be that (a) the “standard” conception of spoken language semantics was insufficiently inclusive, and that (b) when sign is compared to speech-plus-gesture rather than to speech alone, the two systems display similar expressive resources.

So, does speech-plus-gesture really display the same expressive resources as sign? In order to adjudicate the debate, we need a better understanding of the semantic status of iconic enrichments. A distinction will prove fruitful: in "internal" enrichments, the form of an expression is iconically modulated to affect the meaning of that very expression, as in examples (1)a–b; in “external" enrichments, an expression is iconically enriched by an extraneous element, as in example (2) (= enrichment of punish by a gesture).

1. 2. John _punished his son.

Interesting differences between internal and external enrichments arise upon embedding. The internal enrichments in example (1) behave like standard at-issue (= assertive) contributions and can take scope under logical operators – thus example (3)a means something like “If the talk is very long, I'll leave before the end”; and similarly example (3)b means that if my group grows a lot, John will lead it.

1. 3.

   1. a. If the talk is loooooong, I'll leave before the end.

   2. b. …IF POSS-1 GROUP GROW_broad, IX-b JOHN LEAD. (ASL; video 33, 71; 2 trials)

Recent discussions suggest that internal enrichments can also have other types of contributions – for instance, presuppositional ones (Schlenker et al. Reference Schlenker, Lamberton and Santoro2013).

External enrichments seem to be more constrained, as illustrated in example (4) (the picture represents a gesture that co-occurs with the expression that immediately follows it).

1. 4.

   1. a. None of these 10 guys punished his son like _this.

   2. b. None of these 10 guys _punished his son.

      => for each of these 10 guys, if he had punished his son, slapping would have been involved

   3. c. None of these 10 guys punished his son / regrets coming

      => each of these 10 guys has a son / came

In the baseline in example (4)a, like this is an at-issue modifier; what is denied is thus that any of the relevant individuals punished his son by slapping him – hence if any punished his son, it was in some other way. The target example in (4)b arguably triggers the opposite inference: For each of the relevant individuals, if he had punished his son, it would have been by slapping him. In this case, the iconic enrichment “projects” (in universal form) beyond the negative expression none. I have argued (Schlenker Reference Schlenker2015; Reference Schlenkerunder review) that this behavior is reminiscent of presuppositions, illustrated with the presupposition triggers his son and regrets in example (4)c: These, too, yield universal inferences under none.

A similar behavior is obtained with the disgusted face :-( in example (5)a: It too gives rise to a universal inference under none. Interestingly, this case of external enrichment can be extended to ASL, as in example (5)b; while the latter is slightly degraded, it gives rise to a universal inference as well – and since the iconic enrichment of the manual sign is facial, it too counts as external.

1. 5.

   1. a. None of my friends goes :-(_[skiing with his parents]

      => in my friends' case, skiing with one's parents is no fun

   2. b. ? YOUNG NONE IX-arc-a :-(_[SPEND TIME WITH POSS-arc-a PARENTS]

      => spending time with one's parents is disgusting (ASL; video 33, 0472, 2 trials)

Finally, the gestures in examples (6)a(1)–(6)b(1) follow rather than co-occur with the expression they modify, and they arguably behave like the appositives in examples (6)a(2)–(6)b(2) (Schlenker Reference Schlenkerunder review; but see Ebert & Ebert Reference Ebert and Ebert2014). For example, both constructions can modify a bottle of beer in the scope of a philosopher, but not of no philosopher – a standard property of appositives (see Potts Reference Potts2005; Nouwen Reference Nouwen2007).

1. 6.

   1. a. A philosopher brought a bottle of beer

      (1) –  / (2) , which was _this large.

   2. b. ??No philosopher brought a bottle of beer

      (1) –  / (2) , which was _this large.

A generalization suggests itself: internal enrichments may have any semantic status, and in particular they may be at-issue, whereas external enrichments are not normally at-issue. If correct, this has an important consequence: Since internal enrichments are so impoverished in spoken language, even when co-speech gestures are reintegrated into spoken language semantics, there will be far-reaching expressive differences between speech-plus-gesture and sign.