In psycholinguistics, language production is the production of spoken or written language. It describes all of the stages between having a concept, and translating that concept into linguistic form. In computational linguistics/natural language processing and artificial intelligence, the term natural language generation (NLG) is more common, and those models may or may not be psychologically motivated.
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Stages of production
The basic loop occurring in the creation of language consists of the following stages:
Serial model
A serial model of language production divides the process into several stages. For example, there may be one stage for determining pronunciation and a stage for determining lexical content. The serial model does not allow overlap of these stages, so they may only be completed one at a time.
Connectionist model
Several researchers have proposed a connectionist model, one notable example being Dell. According to his connectionist model, there are four layers of processing and understanding: semantic, syntactic, morphological, and phonological. These work in parallel and in series, with activation at each level. Interference and misactivation can occur at any of these stages. Production begins with concepts, and continues down from there. One might start with the concept of a cat: a four-legged, furry, domesticated mammal with whiskers, etc. This conceptual set would attempt to find the corresponding word {cat}. This selected word would then select morphological and phonological data /k / at/. The distinction of this model is that, during this process, other elements would also be primed ({rat} might be somewhat primed, for example), as they are physically similar, and so can cause conceptual interference. Errors might also occur at the phoneme level, as many words are phonetically similar, e.g. mat. Substitutions of similar consonant sounds are more likely to occur, e.g. between plosive stop consonants such as d, p and b. Lower primed words are less likely to be chosen, but interference is thought to occur in cases of early selection, where the level of activation of the target and interference words is at the same level.
Fluency
Can be defined in part by prosody, which is shown by a smooth intonation contour, and a number of other elements: control of speech rate, relative timing of stressed and unstressed syllables, changes in amplitude, and changes in fundamental frequency
Research into production
There are two main types of research into speech production. One type focuses on using the analysis of speech errors. The other looks at reaction-time data from picture-naming latencies. Although originally disparate, these two methodologies are generally looking at the same underlying processes of speech production.
Speech errors
Analysis of speech errors has found that not all are random, but rather systematic and fall into several categories. Although speech production is very fast, (2 words per second) the error rate of the utterances are relatively rare (less than 1/1000) and those errors are categorized as follows: