A growth point (GP) is a dynamic unit of online verbal thinking. It is sui generis-not the same as units of synchronic linguistic description (words, morphemes, etc.). The GP combines unlike modes of cognition imagery and linguistic categorial content. Combining unlike modes is critical since the combination explains how the GP is unstable and thus able to fuel an imagery-language dialectic. One way to conceptualize the GP is as an image that is being categorized linguistically -an image with a foot in the door of language, as it were. The combination is called a growth point since it is meant to be the initial form of a thinking-for-speaking unit out of which a dynamic process of organization emerges. It is also called a GP since it is a theoretical unit in which the principles that explain the mental growth of children - differentiation, internalization, dialectic, and reorganization- also apply to realtime utterance generation by adults (and children). A final reason is that a GP addresses the concept that there is a specific starting point for a thought. Although an idea unit continues out of the preceding context and has ramifications in later speech, it does not exist at all times, and comes into being at some specific moment; the formation of a growth point is this moment, theoretically, and its is made visible in the onset of the gesture (the preparation phase specifically; see the section on annotation).
The GP is also a guide for gesture and speech transcription and analysis. GPs are inferred from the totality of communicative events with special focus on speech-gesture synchrony and co-expressivity, and these properties must be coded exactly. Our methods for achieving such records are described elsewhere on this site. Co-expressivity means that the gesture synchronizes with speech segment(s) that, in the context of speaking, express the same underlying idea unit as the gesture -these speech segments may or may not be 'lexical affiliates'.
Finally, and no less crucial, a GP is inseparable from its context of speaking. The term 'context' is often simply a term for anything that is unanalyzed (saying it is 'due to context'), but in the GP the context has a definite meaning and role. Briefly, a GP models the act of speaking as a kind of differentiation. The slogan could be synthesis by analysis (inverting analysis by synthesis, which similarly tried to bring the perceptual and the generative together). Differentiation requires a background, and this is the systematic role of context. A GP always implies a context: differentiation of the GP cannot occur without it. The context must be one in which the proposed GP can take shape. This way of reasoning has a methodological implication, for a context that is inappropriate falsifies the hypothesized GP. The conditions that contexts must meet in order for a GP to take form are explained in the following.
Psychological predicates and fields of opposition.
Growth points are the newsworthy elements in the immediate context of speaking. These gestures surgically zero in on this novel content. GPs are, to adopt a concept from Vygotsky, psychological predicates (not always grammatical predicates).
The concept of a psychological predicate illuminates the link between the GP and the context of speaking. Defining a psychological predicate (and hence a GP) requires reference to the context; this is because the psychological predicate and its context are mutually defining. The GP:
- Marks a significant departure in the immediate context; and
- Implies this context as a background.
Regarding the GP as a psychological predicate suggests a mechanism of GP formation in which differentiation of a focus of content from a background plays an essential part. Such differentiation is validated by a very close temporal connection of gesture strokes with the peak of acoustic output in speech. Shuichi Nobe has documented this connection instrumentally: "The robust synchrony between gesture strokes and the peaks of acoustic aspects suggests that the information the gesture stroke carries has an intrinsic relationship with the accompanying speech information prominently pronounced with these peaks. The manifestation of the salient information seems to be realized through the synchronization of these two modalities".
Regarding the GP as a psychological predicate also clarifies the sense in which we use the term 'context'. The contextual background indexes and is constrained by external conditions, both social and material, but an essential fact is that the contextual background is also under the control of the speaker; it is a mental construction, part of the speaker's effort to construct a meaning. The speaker shapes the background in a certain way, in order to make possible the intended significant contrast within it. Background and contrast are both necessary and are constructed together. A new 'meaning' is a fresh differentiation from a constructed background -meaning has this dual character of being both a focal point and an implied background, and both are necessary (it is not an 'accumulation' or a 'deposit' in some kind of memory bank).
We use the terms field of oppositions and significant (or newsworthy) contrast to refer to this constructed background and the differentiation of the GP. All of this is meant to be a dynamic, continuously updated process in which new fields of oppositions are formed and new GPs or psychological predicates are differentiated in ongoing cycles of speaking and thinking.
The close synchrony of speech and gesture in daily speech is explained as the product of GP differentiation. Speech-gesture synchrony is an active part of the construction of the meaning.
The 'catchment' is the contextual twin of the growth point. A catchment is recognized when one or more gesture features recur in at least two (not necessarily consecutive) gestures. The logic is that the recurrence of imagery in the speaker's thinking generates recurrent gesture features. Recurrent features suggest a common discourse theme. These gesture features can be detected. Working backwards, the recurring features offer clues to the cohesive linkages in the text with which it co-occurs. A catchment is a kind of thread of visuospatial imagery that runs through a discourse to reveal the larger discourse units that emerge out of otherwise separate parts.
By discovering the catchments created by a given speaker, we can see what this speaker is combining into larger discourse units -what meanings are being regarded as similar or related and grouped together, and what meanings are being put into different catchments or are being isolated, and thus are seen by the speaker as having distinct or less related meanings. Individuals differ in how they divide the world into related and unrelated components. Catchments give us a way of detecting these individual grouping patterns, which are a version of one's cognitive style. To summarize the definition of a catchment:
- A catchment is recognized from recurrences of gesture form features over a stretch of discourse. Catchments are recognized from 2 or more gestures (not necessarily consecu-tive) with partially or fully recurring features of shape, movement, space, orientation, dynamics, etc.
- A catchment is a kind of thread of consistent dynamic visuospatial imagery running through the discourse segment that provides a gesture-based window into dis-course cohesion.
The logic of the catchment is that discourse themes produce gestures
with recurring features; these recurrences give rise to the catchment.
Thus, working backwards, the catchment offers clues to the cohesive
linkages in the text with which it co-occurs and the fields of
oppositions from which GPs are pulled out.