The Role of Gesture in Language, Thought, and Communication

David McNeill, University of Chicago

The growth point (GP) is an analytic unit combining imagery and linguistic categorial content.  GPs are inferred from the totality of communicative events with special focus on speech-gesture synchrony and semantic co-expressivity.  Following Vygotsky (1987), a GP is intended to be a minimal psychological unit; that is, the smallest unit (in his analysis) that retains the essential properties of a whole.  In our case, the whole is an image and a linguistically-codified meaning category, such as we see in the speech-gesture window.  The GP is meant to be the starting point of the utterance generation process.  GPs are, to use another of Vygotsky's concepts, psychological predicates (not necessarily grammatical predicates).  Regarding the GP as a psychological predicate suggests a mechanism of GP formation in which differentiation of a novel focus from a background plays an essential part.  Differentiation, packaged into a GP, is the launching point of thinking for speaking and utterances.

A case study of a GP is a non-grammatical combination, "it down", plus a gesture in which the hands appear to thrust down a large bowling ball. This comprised the GP of  a full sentence, "and drops it down the drainpipe," in a cartoon story narration.  This inference is based on speech-gesture synchrony and co-expressiveness.  "It down" plus the downward gesture is the core cognition of the utterance as a whole in this analysis, a psychological predicate in a particular context.  Functionally, the image provided a holistic version of the concept at the moment of speaking while the linguistic categorial content ("it", "down") located this image within the socially-constituted linguistic system.   Both the holistic and analytic components are essential to a complete cognition.  From this GP, the rest of the utterance is ‘unpacked’ via further meaning generation and contextual contrasts.

A related concept is that of a catchment -- a gestural trace of thematic cohesiveness. Catchments are manifested in groups of 2 or more gestures (not necessarily consecutive) with partially recurring gesture features of movement, space, orientation, dynamics, etc. across discourse segments, forming a thematic unit.  Languages may differ in their preferred catchment structures as well as in their growth points.  Indeed, these should be coordinated.   In the "it down" case, the catchment consisted of four non-consecutive gestures (of which one was the two-handed gesture with "it down") and was based on a conflict of paths: the bowling ball DOWN vs. Sylvester UP, with the further significance of the directions as opposed forces (evil vs. good).   Catchments complement the GP analysis by giving a snapshot of the contexts against which the GPs are differentiated.

Different languages induce different GPs.  In motion event descriptions, English speakers choose to treat path as a series of short, straight segments and path junctures as landmarks past which the moving figure goes, but not as destinations.   The bowling ball's path was segmented  into 4 segments by the speaker of the "it down" example.   Spanish speakers, in contrast, treat even complex curvilinear paths as unbroken trajectories, but treat  junctures as momentary termini. These differences  across languages reveal impacts of language form on GPs – English hyper-segmentation of GPs  reflecting satellite-framed packaging where path information is divided into any number of satellite segments, Spanish curvilinearity reflecting verb-framed packaging where  path is completely encased in a single verb.