Subvocalization

Subvocalization has been considered as far back as 1868. who concluded that silent reading was the only mental activity that created considerable movement of the larynx. In 1950, Åke Werner Edfeltreached 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, Edfelt seconded this opinion. ==Techniques for studying subvocalization==

Subvocalization is commonly studied using electromyography (EMG) recordings, concurrent speaking tasks, shadowing, 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. ==Evolutionary background==

The exploration into the evolutionary background of subvocalization is currently very limited. The little known is predominantly about language acquisition and memory. Evolutionary psychologists suggest that the development of subvocalization is related to modular aspects of the brain. There has been a great amount of exploration on the evolutionary basis of universal grammar. The idea is that although the specific language one initially learns is dependent on one's culture, all languages are learned through the activation of universal "language modules" that are present in each of us. This concept of a modular mind is a prevalent idea that will help explore memory and its relation to language more clearly, and possibly illuminate the evolutionary basis of subvocalization. Evidence for the mind having modules for superior function is the example that hours may be spent toiling over a car engine in an attempt to flexibly formulate a solution, but, in contrast, extremely long and complex sentences can be comprehended, understood, related and responded to in seconds. The specific inquiry into subvocalization may be minimal right now but there remains much to investigate in regard to the modular mind. ==Associated brain structures and processes==

The brain mechanics of subvocalization are still not well understood. It is safe to say that more than one part of the brain is used, and that no single test can reveal all the relevant processes. Studies often use event-related potentials; brief changes in an EEG (electroencephalography) to show brain activation, or fMRIs. Subvocalization is related to inner speech; when inner speech is used, there is bilateral activation in predominantly the left frontal lobe. This activation could suggest that the frontal lobes may be involved in motor planning for speech output. There is evidence for significant left hemisphere activation in the inferior and middle frontal gyri and inferior parietal gyrus during subvocal rehearsal. Silent speech-reading and silent counting are also examined when experimenters look at subvocalization. These tasks show activation in the frontal cortices, hippocampus and the thalamus for silent counting. is an active subvocal rehearsal mechanism, activation originating mostly in the left hemispheric speech areas: Broca's, lateral and medial premotor cortices and the cerebellum. ==Role of subvocalization in memory processes==

The phonological loop and rehearsal The ability to store verbal material in working memory, and the storage of verbal material in short-term memory relies on a phonological loop. Subvocalization and the phonological loop interact in a non-dependent manner demonstrated by their differential requirements on different tasks. The working memory span is a behavioural measure of "exceptional consistency" and is a positive function of the rate of subvocalization. Experimental data has shown that this span size increases as the rate of subvocalization increases, and the time needed to subvocalize the number of items comprising a span is generally constant. Short-term memory The role of subvocal rehearsal is also seen in short-term memory. Research has confirmed that this form of rehearsal benefits some cognitive functioning. The production of acoustic errors in short-term memory is also thought to be, in part, due to subvocalization. Individuals who stutter and therefore have a slower rate of subvocal articulation also demonstrate a short-term reproduction of serial material that is slower as compared to people who do not stutter. Encoding Subvocalization plays a large role in memory encoding. Subvocalization appears to facilitate the translating of visual linguistic information into acoustic information as words being heard are already in acoustic form and therefore enter short-term memory directly without use of subvocal articulation. Furthermore, subvocalization interference impedes reading comprehension but not listening comprehension. ==Role in reading comprehension==

Subvocalization's role in reading comprehension can be viewed as a function of task complexity. Subvocalization is involved minimally or not at all in immediate comprehension. For example, subvocalization is not used in the making of homophone judgements is thought to allow for the integration of past concepts with those currently being processed. ==Comparison to speed reading==

Advocates of speed reading generally claim that subvocalization places extra burden on the cognitive resources, thus slowing the reading down. Speedreading courses often prescribe lengthy practices to eliminate subvocalizing when reading. Normal reading instructors often simply apply remedial teaching to a reader who subvocalizes to the degree that they make visible movements on the lips, jaw, or throat. At the slower rates (memorizing, learning, and reading for comprehension), subvocalizing by the reader is very detectable. At the faster rates of reading (skimming and scanning), subvocalization is less detectable. For competent readers, subvocalizing to some extent even at scanning rates is normal. Typically, subvocalizing is an inherent part of reading and understanding a word. Micro-muscle tests suggest that full and permanent elimination of subvocalizing is impossible. This may originate in the way people learn to read by associating the sight of words with their spoken sounds. Sound associations for words are indelibly imprinted on the nervous system—even of deaf people, since they will have associated the word with the mechanism for causing the sound or a sign in a particular sign language. At the slower reading rates (100–300 words per minute), subvocalizing may improve comprehension. Subvocalizing or actual vocalizing can indeed be of great help when one wants to learn a passage verbatim. This is because the person is repeating the information in an auditory way, as well as seeing the piece on the paper. ==Auditory imagery==

The definition of auditory imagery is analogous to definitions used in other modalities of imagery (such as visual, auditory and olfactory imagery) in that it is, according to Intons-Peterson (1992), "the introspective persistence of an auditory experience, including one constructed from components drawn from long-term memory, in the absence of direct sensory instigation of that experience.". Auditory imagery is often but not necessarily influenced by subvocalization, These findings suggest that subvocalization is common to both auditory imagery and rehearsal. In objection to a subvocalization mechanism basis for auditory imagery is in the fact that a significant amount of auditory imagery does not involve speech or stimuli similar to speech, such as music and environmental sounds. However, to combat this point, it has been suggested that rehearsal of non-speech sounds can indeed be carried out by the phonological mechanisms previously mentioned, even if the creation of nonspeech sounds within this mechanism is not possible. ==Role in speech==

There are two general types of individuals when it comes to subvocalization. There are Low-Vocalizers and High-Vocalizers. Using electromyography to record the muscle action potential of the larynx (i.e. muscle movement of the larynx), an individual is categorized under a high or low vocalizer depending on how much muscle movement the muscles in the larynx undergo during silent reading. Regulation of speech intensity Often in both high and low vocalizers, the rate of speech is constantly regulated depending on intensity/volume of words (said to be affected by long delays between readings) and increasing the delay of speech and hearing ones' voice is an effect called “delayed auditory feedback”. As articulation of similar words is affecting subvocalization, there is an increase in acoustic errors for short-term memory and recall. An example of articulation suppression is repeating the same word over many times such as the and attempting to memorise other words into short-term memory. Even though primary cues may be given for these words in attempt to retrieve them, words will either be recalled for the incorrect cue or will not be recalled at all. ==Schizophrenia and subvocalization==

People with schizophrenia known to experience auditory hallucinations could show the result of over-activation of the muscles in the larynx. Using an electromyography to record muscle movement, individuals experiencing hallucinations showed greater muscle activation before these hallucinations occurred. This small fact could be a clue to finding if there is a true link between subvocalization and hallucinations, but it is very difficult to see this connection because not many patients experience hallucinations. ==References==