Schemas and instances
A defining property of the cognitive model is that the characterisation of linguistic units as symbolic units is not restricted to the content system but also applies to the grammatical system. In other words, grammatical units are also seen as form-meaning pairings. As we have seen, while the meaning associated with open-class units is specific (rich in conceptual content), the meaning associated with closed-class units is schematic. From this perspective, there is no need to posit a sharp boundary in the grammar between open-class and closed class units. Instead, specificity versus schematicity of meaning can be viewed as the poles of a continuum, according to which both open-class and closed-class expressions are meaningful, each making a distinct and necessary contribution to the cognitive representation prompted by the utterance. According to Langacker, the inventory of symbolic units is organised by schema-instance relations. A schema is a symbolic unit that emerges from a process of abstraction over more specific symbolic units called instances. In other words, schemas form in the mental grammar when patterns of similarity are abstracted from utterances, giving rise to a more schematic representation or symbolic unit. The relationship between a schema and the instances from which it emerges is the schema-instance relation. This relationship is hierarchical in nature.
Consider common nouns like cats, dogs, books, flowers and so on. Each of these expressions is a highly entrenched symbolic unit. For example, the symbolic unit cats might be represented by the formula in (43):
The representations in SMALL CAPITALS indicate the semantic poles and those in the International Phonetic Alphabet (IPA) font represent the phonological poles. The slash indicates the symbolic link between semantic and phonological poles, and the hyphen indicates the linking of symbolic units to form a complex structure. Given that there are many cases of regular plural nouns in the linguistic inventory, this regular pattern is captured by a schematic symbolic unit which contains only schematic information about the construction. This schema for plural nouns is represented in (44).
In this schematic representation, the semantic pole THING indicates a noun but its corresponding phonological unit is left blank to indicate that this construction represents nouns in general. Each fully specified unit corresponding to this schema (for example, the expressions cats, dogs, books, flowers) represents an instance of the schema. The hierarchical relationship between a schema and its instances is captured in Figure 14.8.
It is important to point out here that the schema-instance relation is not restricted to symbolic units. For Langacker, the schema is any superordinate (more general) element in a taxonomy and the instance is any subordinate (more specific) element. In other words, the schema-instance relation represents a type of categorisation relation. In terms of phonological units, for example, the phoneme is the schema and its allophones are instances. In terms of semantic units, the concept FLOWER is schematic in relation to the instances ROSE, LILY and GERBERA. An instance is said to elaborate its schema, which means that it provides more specific meaning. For example, MAMMAL is more specific than ANIMAL, and in turn MONKEY is more specific than MAMMAL.
