MA ELT & Applied Linguistics: Psycholinguistics Willem J M Levelt’s Theory of Speaking

Theoretical Basis Levelt took as his starting point the principle that speaking is best described by examples of successful speech, and not by analysing errors. His model attempts to show how the speech act is a process moving linearly from intention to articulation, although he does recognise that there are some feedback loops. For Levelt, speaking and listening are separate processes and physically separate in the brain. He is concerned with speaking and does not specify the nature of the listening engine. Levelt’s speech engine has three major processing modules, and it uses two sources of knowledge, one inside the language engine (the lexicon) and one outside it (the encyclopedia). There is thus a separation of semantic content from the words themselves; words are just phonological tags which are activated by semantic look-up – a kind of reverse dictionary.

The Model of the Theory

Willem J M Levelt (1998). Speaking: from intention to articulation. MIT Press: Cambridge, Mass, USA. p9.

How the Model Works The intention to speak involves the activation of knowledge which is held in general cognition (the encyclopedia). This consists of two types of semantic content: objects and relationships between them. The conceptualizer module takes this intentional block of knowledge as input and overlays it with a grammatical form – producing a linear what-did-what preverbal message, which is amenable to being spoken but not yet utterable. This preverbal message is passed to the formulator, where it is grammatically encoded into a surface structure of the language being spoken. The lexicon is also referenced to find the appropriate word which

matches the semantic content of each preverbal unit. These words have two parts: the form, which determines which inflection or case is appropriate for the grammatical context; and the lemma, which contains the phonetic (and graphological?) form of the intended semantic content. The lemma also contains a sense-meaning, which is how the amorphous semantic content finds the appropriate lemma. The output from the formulator is inner speech – a language construct in all but utterance. From the formulator the inner speech produced is passed to the articulator, which is a dumb programmable module. It just runs the phonetic program generated by the formulator, and thus produces the utterance, or overt speech. This is not the end of the story, though, because the speaker is part of their own audience. The utterance is received by the speaker’s speech-comprehension system and passed back to the speech engine for checking. The model gets a little hazy at this point: clearly the utterance has to be checked by the conceptualizer, the formulator and the original intention to ensure its integrity, but Levelt is not fully clear on how this happens.

What is a Lemma? For Levelt, a lemma is a look-up, selecting the appropriate phonological form based on the sensory-meaning. The word comes from ancient Greek, where it means a pre-established fact. Warning! Levelt’s usage of the term is idiosyncratic. It does not match with the meanings attached to lemma in other areas of linguistics!

The Nature of the Theory The theory is …

Nativist: the speaking engine is a pre-existing system in cognition which is dedicated to producing speech.

Generative: based on the Principles & Parameters approach, it sees the generation of speech as a movement from deep structure to surface structure.

Strongly modular: the speech engine is composed of a series of modules which are specialised.

Hierarchical: the speech system is composed of modules which have sub-modules.

Problems with the Theory It remains a theory. Evidence of its actuality in the brain remains elusive.

It is mechanistic, it uses a highly constrained linear model to describe what (if it is like other cognition) is probably a massively parallel process.

Sense-meaning depends on lexicon: if you have only one word for the emotion of happiness it has to cover everything from satisfaction to delight. Does this mean that a limited lexicon affects how you are able to differentiate happiness, or only how you are able to express it? (Sapir-Whorf hypothesis).

Are words actually stored as stems and affixes? There is some evidence for this with regular less common forms, e.g. UN-CLEAR-ABLE, but common or irregular items (e.g. UNHAPPINESS, DYSFUNCTION) seem to be held as separate lexical entries. The lexical strategy may vary from brain to brain.

The encyclopedia is separate to the dictionary, so how is the encyclopedia referenced?

The assumption that speech comprehension is a separate system to speech production means that self-monitoring can only occur after utterance; but self-correction seems to happen during articulation as well as before and after it (the half-uttered syllable).

Levelt’s model does not address cases where self-monitoring is problematic – such as where a stutterer becomes worse when they become aware of themselves speaking.

More Information See

http://www.nupffale.ufsc.br/newsounds/Papers/17.Fernandes-Boechat_Brito.pdf

http://www.aclweb.org/anthology/J/J90/J90-1012.pdf for fuller descriptions of Levelt’s theory of speaking.