Subvocalization

Subvocalization, or silent speech, is the internal speech typically made when reading; it provides the sound of the word as it is read. This is a natural process when reading and it helps the mind to access meanings to comprehend and remember what is read, potentially reducing cognitive load. This inner speech is characterized by minute movements in the larynx and other muscles involved in the articulation of speech. Most of these movements are undetectable (without the aid of machines) by the person who is reading. It is one of the components of Baddeley and Hitch's phonological loop proposal which accounts for the storage of these types of information into short-term memory.

Subvocalization has been considered as far back as 1868. Only in 1899 did an experiment take place to record movement of the larynx through silent reading by a researcher named Curtis, who concluded that silent reading was the only mental activity that created considerable movement of the larynx.

In 1950 Edfelt reached a breakthrough when he created an electrically powered instrument that can record movement. He concluded that newer techniques are needed to accurately record information and that efforts should be made to understand this phenomenon instead of eliminating it. After failed attempts trying to reduce silent speech in study participants, in 1952, it came to the conclusion that silent speech is a developmental activity which reinforces learning and should not be disrupted during development, in 1960 Edeflt seconded this opinion.

Subvocalization is commonly studied using electromyography (EMG) recordings, concurrent speaking tasks,shadowing, and other techniques.

EMG can be used to show the degree to which one is subvocalizing or to train subvocalization suppression. EMG is used to record the electrical activity produced by the articulatory muscles involved in subvocalization. Greater electrical activity suggests a stronger use of subvocalization. In the case of suppression training, the trainee is shown their own EMG recordings while attempting to decrease the movement of the articulatory muscles. The EMG recordings allows one to monitor and ideally reduce subvocalization.

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