Elements
Mental spaces are temporary conceptual domains constructed during ongoing discourse. These spaces contain elements, which are either entities constructed on-line or pre-existing entities in the conceptual system. The linguistic expressions that represent elements are noun phrases (NPs). These include linguistic expressions like names (Fred, Elvis, Madonna, Elizabeth Windsor, Tony Blair, James Bond), descriptions (the Queen, the Prime Minister, a green emerald, a Whitehouse intern, an African elephant), and pronouns (she, he, they, it).
NPs can have a definite interpretation or an indefinite interpretation. Briefly, NPs that have a definite interpretation include those that occur with the definite article the, (the sleepy koala) and names (Margaret Thatcher, James Bond). NPs that have indefinite interpretation include those occurring with the indefinite article a (a sleepy koala) and ‘bare plurals’ (koalas). NPs with indefinite interpretation typically introduce new elements into the discourse: elements that are unfamiliar or have not already been mentioned in the conversation (I’ve bought a new sofa!). NPs with definite interpretation are said to function in the presuppositional mode, because they presuppose existing knowledge. This means that they refer to elements that are already accessible: elements familiar to speaker and hearer, or already part of the conversation (The new sofa clashes with the curtains). In Mental Spaces Theory, elements introduced in the presuppositional mode are said to be propagated, which means that they spread to neighbouring spaces. This process of propagation is governed by the Optimisation Principle. This principle allows elements, together with their properties and relations, to spread through the network or lattice of mental spaces, unless the information being propagated is explicitly contradicted by some new information that emerges as the discourse proceeds. This principle enables mental space configurations to build complex structures with a minimum of explicit instructions.
