Editing Subvocalization

{{Short description|Internal process while reading}}
{{Reading}}
'''Subvocalization''', or silent [[Speech communication|speech]], is the [[internal speech]] typically made when [[reading (activity)|reading]]; it provides the [[sound]] of the [[word]] as it is read.<ref name=carter>Carver, R. P. (1990) Reading Rate: A Comprehensive Review of Research and Theory (1990)</ref><ref name=History>Cleland, D. L., Davies, W. C and T. C. 1963. Research in Reading. ''The Reading Teacher'', ''16''(4), 224-228</ref> This is a natural process when reading, and it helps the [[mind]] to access meanings to comprehend and [[memory|remember]] what is read, potentially reducing [[cognitive load]].<ref name=rayner>Rayner, Keith and Pollatsek, Alexander (1994) The Psychology of Reading</ref>

This inner speech is characterized by minuscule 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.<ref name=rayner /> It is one of the components of [[Alan Baddeley]] and [[Graham Hitch]]'s [[phonological loop]] proposal which accounts for the storage of these types of information into short-term memory.<ref name=Smith>Smith, J. D., Wilson, M., & Reisberg, D. (1995). The role of subvocalization in auditory imagery. ''Neuropsychologia, 33(11)'', 1433-1454.</ref>

[[File:Sagittalmouth.png|thumb|alt=the larynx and associated musculature|The larynx and associated musculature]]

==History of subvocalization research==
Subvocalization has been considered as far back as 1868.<ref name=History/> Only in 1899 did an experiment take place to record movement of the [[larynx]] through [[silent reading]] by a researcher named H.S. Curtis,<ref>{{Cite journal |last=Curtis |first=H.S |date=1900 |title=Automatic Movements of the Larynx |journal=American Journal of Psychology |volume=11 |issue=11 |pages=237–239|doi=10.2307/1412271 |jstor=1412271 }}</ref> who concluded that silent reading was the only mental activity that created considerable movement of the larynx.<ref name=History/>
 
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.<ref name=History/> After failed attempts trying to reduce silent speech in study participants, in 1952, it{{who|date=July 2019}} came to the conclusion that silent speech is a developmental activity which reinforces learning and should not be disrupted during [[Child development|development]].{{Citation needed|reason=No researcher named|date=July 2019}} In 1960, Edfelt seconded this opinion.<ref name=History/>

==Techniques for studying subvocalization==
Subvocalization is commonly studied using [[electromyography]] (EMG) recordings,<ref name=Locke>Locke, J., & Fehr, F. (1972). Subvocalization of Heard or Seen Words Prior to Spoken or Written Recall. The American Journal of Psychology, 8(1), 63-68.</ref> concurrent speaking tasks,<ref name=Levy>Levy, B. A. (1971). Role of Articulation in Auditory and Visual Short-Term Memory. Journal of Verbal Learning and Verbal Behavior, 10, 123-132.</ref><ref name=Daneman>Daneman, M., & Newson, M. (1992). Assessing the Importance of Subvocalization in Normal Silent Reading. Reading and Writing: An Interdisciplinary Journal, 4, 55-77.</ref><ref name=Slowiaczek>Slowiaczek, M., & Clifton, C. (1980). Subvocalization and reading for meaning. Journal of Verbal Learning and Verbal Behavior, 19.5, 573-582.</ref> [[Speech shadowing|shadowing]],<ref name=Levy/> and other techniques.<ref name=Levy/><ref name=Daneman/>

EMG can be used to show the degree to which one is subvocalizing<ref name=Locke/> or to train subvocalization suppression.<ref name=Cole>Cole, R. A., & Young, M. (1975). Effect of subvocalization on memory for speech sounds. Journal of Experimental Psychology: Human Learning and Memory, 1(6), 772-779.</ref> 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.<ref name=Locke/><ref name=Cole/> In the case of suppression training, the trainee is shown their own EMG recordings while attempting to decrease the movement of the articulatory muscles.<ref name=Cole/> The EMG recordings allows one to monitor and ideally reduce subvocalization.<ref name=Cole/>

In concurrent speaking tasks, participants of a study are asked to complete an activity specific to the experiment while simultaneously repeating an irrelevant word.<ref name=Levy/> For example, one may be asked to read a paragraph while reciting the word "cola" over and over again.<ref name=Slowiaczek/> Speaking the repeated irrelevant word is thought to preoccupy the articulators used in subvocalization.<ref name=Levy/> Subvocalization, therefore, cannot be used in the mental processing of the activity being studied. Participants who had undergone the concurrent speaking task are often compared to other participants of the study who had completed the same activity without subvocalization interference. If performance on the activity is significantly less for those in the concurrent speaking task group than for those in the non-interference group, subvocalization is believed to play a role in the mental processing of that activity.<ref name=Levy/><ref name=Daneman/><ref name=Slowiaczek/><ref name=Cole/> The participants in the non-interference comparison group usually also complete a different, yet equally distracting task that does not involve the articulator muscles <ref name=Daneman/><ref name=Cole/>(i.e. tapping). This ensures that the difference in performance between the two groups is in fact due to subvocalization disturbances and not due to considerations such as task difficulty or a divide in attention.<ref name=Daneman/><ref name=Cole/>

Shadowing is conceptually similar to concurrent speaking tasks. Instead of repeating an irrelevant word, shadowing requires participants to listen to a list of words and to repeat those words as fast as possible while completing a separate task being studied by experimenters.<ref name=Levy/>

Techniques for subvocalization interference may also include counting,<ref name=Daneman/><ref name=Slowiaczek/> chewing<ref name=Eiter/> or locking one's jaw while placing the tongue on the roof of one's mouth.<ref name=Eiter/>

[[Subvocal recognition]] involves monitoring actual movements of the [[tongue]] and [[vocal cords]] that can be interpreted by [[Electromagnetism|electromagnetic]] sensors. Through the use of electrodes and [[nanocircuitry]], synthetic telepathy could be achieved allowing people to communicate silently.<ref>{{cite web|url=http://txchnologist.com/post/43496630304/temporary-tattoos-could-make-electronic-telepathy|title=Temporary Tattoos Could Make Electronic Telepathy, Telekinesis Possible|website=Txchnologist.com|accessdate=10 June 2016|archive-url=http://web.archive.org/web/20150703132730/https://txchnologist.com/post/43496630304/temporary-tattoos-could-make-electronic-telepathy|archive-date=3 July 2015 | url-status = dead}}</ref>

==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 [[Modularity of mind|modular]] aspects of the brain.<ref name=evolution>Buller, D. J. (2005). ''Adapting Minds: Evolutionary Psychology and the Persistent Quest for Human Nature''. Massachusetts: The MIT Press</ref> There has been a great amount of exploration on the evolutionary basis of [[universal grammar]].<ref name=evolution/> 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.<ref name=evolution/> 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.<ref name=evolution/> The specific inquiry into subvocalization may be minimal right now{{when|date=December 2019}} 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 potential]]s; brief changes in an EEG ([[electroencephalography]]) to show brain activation, or [[Functional magnetic resonance imaging|fMRIs]].

Subvocalization is related to inner speech; when inner speech is used, there is bilateral activation in predominantly the [[Frontal lobe|left frontal lobe]].<ref name=brainstructures>Girbau, D. (2007). A Neurocognitive Approach to the Study of Private Speech. ''The Spanish Journal of Psychology'', ''10''(1), 41-51</ref> This activation could suggest that the frontal lobes may be involved in [[motor planning]] for speech output.<ref name=brainstructures/>

Subvocal rehearsal is controlled by [[Top-down and bottom-up design|top-down processing]];<ref name=brainstructures/> conceptually driven, it relies on information already in memory.<ref name=brainstructures2>Klob, B. & Whishaw, I.Q. (2009). ‘’Fundamentals of Human Neuropsychology’’ (6th ed.). New York, NY: Worth Publishers</ref> There is evidence for significant left hemisphere activation in the [[Inferior frontal gyrus|inferior]] and [[Middle frontal gyrus|middle frontal gyri]] and inferior parietal gyrus during subvocal rehearsal.<ref name="brainstructures"/> [[Broca's area]] has also been found to have activation in other studies exploring subvocal rehearsal.<ref name=brainstructures3>Burgess, N. & Hitch, G. J. (1999). Memory for Serial Order: A Network Model of the Phonological Loop and its Timing. ''Psychological Review'', ''106''(3), 551-581</ref>

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.<ref name=brainstructures/> Silent-reading activates similar areas of the [[Primary auditory cortex|auditory cortex]] that are involved in listening.<ref name=brainstructures/>
    
Finally, the [[Baddeley's model of working memory|phonological loop]]; proposed by Baddeley and Hitch as "being responsible for temporary storage of speech-like information"<ref name=brainstructure4>Baddeley, A., Eysenck, M. W. & Anderson, M. C. (2009). ''Memory''. New York, NY: Psychology Press</ref> 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]].<ref name=brainstructures5>Gruber, O. (2001). Effects of Domain-specific Interference on Brain Activation Associated with Verbal Working Memory Task Performance. ''Cerebral Cortex'', ''11'', 1047-1055</ref>

==Role of subvocalization in memory processes==
===The phonological loop and rehearsal===
{{further|Phonological loop}}

The ability to store verbal material in [[working memory]], and the storage of verbal material in [[short-term memory]] relies on a phonological loop.<ref name=Smith/> This loop, proposed by Baddeley and Hitch, represents a system that is composed of a short-term store in which memory is represented [[phonology|phonologically]], and a rehearsal process. This rehearsal preserves and refreshes the material by re-enacting it and re-presenting it to short-term storage, and subvocalization is a major component of this rehearsal.<ref name=Smith/> The phonological loop system features an interaction between subvocal rehearsal and specific storage for phonological material.<ref name=Smith/> The phonological loop contributes to the study of the role of subvocalization and the inner voice in auditory imagery.<ref name=Hubbard>Hubbard, T.L. (2010). Auditory imagery: empirical findings. ''Psychological Bulletin, 136(2)'', 302-329.</ref> Subvocalization and the phonological loop interact in a non-dependent manner demonstrated by their differential requirements on different tasks.<ref name=Hubbard/> The role of subvocalization within the workings of memory processes is heavily reliant on its involvement with Baddeley's proposed phonological loop.

===Working memory===
{{further|Working memory}}

There have been findings that support a role of subvocalization in the mechanisms underlying working memory and the holding of information in an accessible and malleable state. Some forms of internal speech-like processing may function as a holding mechanism in immediate memory tasks.<ref name="Standing1980">Standing, L., Bond, B., Smith, P., Isley, C. (1980). Is the immediate memory span determined by subvocalization rate? ''British Journal of Psychology, 71(4)'', 535-539</ref> The working memory span is a behavioural measure of "exceptional consistency" <ref name="Standing1989">Standing, L., & Curtis, L. (1989). Subvocalization rate versus other predictors of the memory span. ''Psychological Reports,65(2)'', 487-495.</ref> 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.<ref name="Standing1980"/> [[fMRI]] data suggests that a sequence of five letters approaches the individual capacity for immediate [[Recollection|recall]] that relies on subvocal rehearsal alone.<ref name=Logie>Logie, R.H., Venneri, A., Sala, S.D., Redpath, T.W., Marshall, I. (2003). Brain activation and the phonological loop: the impact of rehearsal. ''Brain and Cognition, 53(2)'', 293-296.</ref>

===Short-term memory===
{{further|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 [[cognition|cognitive]] functioning.<ref name=Smith/> Subvocal movements that occur when people listen to or rehearse a series of speech sounds will help the subject to maintain the [[phoneme|phonemic]] representation of these sounds in their short-term memory, and this finding is supported by the fact that interfering with the overt production of speech sound did not disrupt the encoding of the sound's features in short-term memory.<ref name=Cole/> This suggests a strong role played by subvocalization in the encoding of speech sounds into short-term memory. It has also been found that language differences in short-term memory performance in bilingual people is mediated, but not exclusively, by subvocal rehearsal.<ref name=Thorn>Thorn, A. S. C., & Gathercole, S. E. (2001). Language differences in verbal short-term memory do not exclusively originate in the process of subvocal rehearsal. ''Psychonomic Bulletin & Review, 8(2)'', 357-364.</ref>

The production of acoustic errors in short-term memory is also thought to be, in part, due to subvocalization.<ref name=Glassman>Glassman, W.E. (1972). Subvocal activity and acoustic confusions in short-term memory. ''Journal of Experimental Psychology, 96(1)'', 164-169.</ref> Individuals who stutter and therefore have a slower rate of subvocal articulation<ref name="Bosshardt 1990">Bosshardt, H. (1990). Subvocalization and reading rate differences between stuttering and nonstuttering children and adults. ''Journal of Speech and Hearing Research, 3''”, 776-785.</ref> also demonstrate a short-term reproduction of serial material that is slower as compared to people who do not stutter.<ref name=Bosshardt>Bosshardt, H. (1993). Differences between stutterers and nonstutterers short-term recall and recognition performance.”Journal of Speech & Hearing Research, 36(2)”, 286-293.</ref>

===Encoding===
Subvocalization plays a large role in memory [[Encoding (memory)|encoding]]. Subvocalization appears to facilitate the translating of visual linguistic information into acoustic information<ref name=Levy/><ref name=Eiter/> and vice versa.<ref name="Locke"/> For example, subvocalization occurs when one sees a word and is asked to say it (see-say condition), or when one hears a word and is asked to write it (hear-write condition), but not when one is asked to see a word and then write it (see-write condition) or hear a word and then say it (hear-say condition).<ref name=Locke/> The see-say condition converts visual information into acoustic information. The hear-write condition converts acoustic information into visual information. The see-write and hear-say conditions, however, remain in the same sensory domain and do not require translation into a different type of code.<ref name=Locke/>

This is also supported by findings that suggest that subvocalization is not required for the encoding of speech,<ref name=Cole/><ref name=Eiter>Eiter, B., & Inhoff, A. (2010). Visual Word Recognition During Reading by Subvocal Articulation. Journal of Experimental Psychology, 35(2), 457-470.</ref> as words being heard are already in acoustic form and therefore enter short-term memory directly without use of subvocal articulation.<ref name=Eiter/> Furthermore, subvocalization interference impedes reading comprehension but not listening comprehension.<ref name=Slowiaczek/>

==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.<ref name=Aaronson>Aaronson, D., & Ferres, S. (1986). Reading Strategies for Children and Adults: A Quantitative Model. Psychological Review, 93(1), 89-112.</ref> For example, subvocalization is not used in the making of homophone judgements<ref name=Smith/> but is used more for the comprehension of sentences and even more still for the comprehension of paragraphs.<ref name="Daneman"/> Subvocalization which translates visual reading information into a more durable and flexible acoustic code<ref name=Bad>Baddeley, A., Eldridge, M., & Lewis, V. (1981). The role of subvocalisation in reading.. The Quarterly Journal of Experimental Psychology A: Human Experimental Psychology, 33(4), 439-454</ref> is thought to allow for the integration of past concepts with those currently being processed.<ref name=Slowiaczek/><ref name=Aaronson/>

==Comparison to speed reading==
Advocates of [[speed reading]] generally claim that subvocalization places extra burden on the cognitive resources, thus slowing the reading down.<ref>{{Citation |url=http://www.pugetsound.edu/academics/academic-resources/cwlt/classes/accelerated-reading/subvocalization/ |title=Subvocalization |work=Accelerated Reading |author=Charlotte Emigh |publisher=University of Puget Sound Center for Writing, Learning & Teaching |year=2011}}</ref> 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 [[lip]]s, [[jaw]], or [[throat]].<ref name=mcwhorter />

Furthermore, fMRI studies comparing fast and slow readers (during a reading task) indicate that between the two groups there are significant differences in the brain areas being activated. In particular, it was found that rapid readers show lower activation in the brain regions associated with speech, which indicates that the higher speeds were attained, in part, by the reduction in subvocalization.<ref>{{cite book|last1=Bremer|first1=Rod|title=The Manual: A Guide to the Ultimate Study Method|publisher=Fons Sapientiae Publishing|isbn=978-0-9934964-0-0|edition=2|url=https://books.google.com/books?id=cEFKjwEACAAJ&q=ultimate+study+method|date=2016-01-20}}</ref>

At the slower rates (memorizing, [[learning]], and reading for [[reading comprehension|comprehension]]), subvocalizing by the reader is very detectable. At the faster rates of reading ([[Skimming (reading)|skimming]] and scanning), subvocalization is less detectable. For competent readers, subvocalizing to some extent even at scanning rates is normal.<ref name=mcwhorter>McWhorter, K. (2002) Efficient and Flexible Reading. Longman</ref>

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.<ref>{{Citation |url=https://blog.superhuman.com/subvocalization/ |title=Subvocalization: What is it and how to avoid it while reading |author=Christina Marfice |year=2021}}</ref> This may originate in the way people learn to read by associating the [[Visual perception|sight]] of words with their spoken sounds. Sound associations for words are indelibly imprinted on the [[nervous system]]&mdash;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]].{{Citation needed|date=May 2012}}

At the slower [[Reading (activity)#Reading rate|reading rates]] (100–300 words per minute), subvocalizing may improve comprehension.<ref name=rayner /> 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==
{{further|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),{{Fcn|date=October 2022}} "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,<ref name=Hubbard/> and has ties to the rehearsal process of working memory.<ref name=Smith/> The conception of working memory relies on a relationship between the "inner ear" and the "inner voice" (subvocalization), and this memory system is posited to be at the basis of auditory imagery. Subvocalization and the phonological store work in partnership in many auditory imagery tasks.<ref name=Smith/>

The extent to which an auditory image can influence detection, encoding and recall of a [[stimulus (psychology)|stimulus]] through its relationships to perception and memory has been documented.<ref name=Hubbard/> It has been suggested that auditory imagery may slow the decay of memory for [[pitch (music)|pitch]], as demonstrated by T. A. Keller, Cowan, and Saults (1995) <ref name=Hubbard/> who demonstrated that the prevention of rehearsal resulted in decreased memory performance for pitch comparison tasks through the introduction of distracting and competing stimuli. It has also been reported that auditory imagery for verbal material is impaired when subvocalization is blocked.<ref name=Aleman>Aleman, A., & vant Wout, M. (2004). Subvocalization in auditory-verbal imagery: Just a form of motor imagery? ''Cognitive Processing, 5(4)'', 228-231.</ref> 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.<ref name=Pitt>Pitt, M. A., & Crowder, R. G. (1992). The role of spectral and dynamic cues in imagery for musical timbre. ''Journal of Experimental Psychology:Human Perception and Performance, 18'', 728–738.</ref> 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.<ref name=Baddeley>Baddeley, A. D., & Logie, R. H. (1992). Auditory imagery and working memory. In D. Reisberg (Ed.), ''Auditory imagery'' pp. 179–197.</ref>

==Role in speech==
There are two general types of individuals when it comes to subvocalization. There are Low-Vocalizers and High-Vocalizers.<ref name=Speech1>Aarons, L. (1971). Subvocalization: Aural and emg feedback in reading. ‘’Perceptual and Motor Skills’’, ‘’33’’(1), 271-306</ref> 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”.<ref name=Speech1/> Increasing the voice intensity while reading was found to be higher in low-vocalizers than high-vocalizers.<ref name=Speech1/> It is believed that because high-vocalizers have greater muscle movement of the larynx during silent reading, low-vocalizers read louder to compensate for this lack of movement so they can understand the material.<ref name=Speech1/> When individuals undergo “feedback training”, where they are conscious of these muscle movements, this difference diminishes.<ref name=Speech1/>

===Role in articulation===
{{further|Manner of articulation|l1=Articulation}}

Articulation during silent speech is important, though speech is not solely dependent on articulation alone. Impairing articulation can reduce sensory input from the muscle movements of the larynx to the brain to understand information being read and it also impairs ongoing speech production during reading to direct thinking.<ref name=Speech1/> Words that are of high similarity minimize articulation, causing interference, and may reduce subvocal rehearsal.<ref name=Speech2>Glassman, W. E. (1972). Subvocal activity and acoustic confusions in short-term memory. ‘’Journal of Experimental Psychology’’, ‘’96’’(1), 164-169.</ref> As articulation of similar words is affecting subvocalization, there is an increase in acoustic errors for short-term memory and recall.<ref name=Speech2/>

Impairing or suppressing articulation causes a greater impact on performance.<ref name=Speech3>Neath, I. (2000). Modeling the effects of irrelevant speech on memory. ''Psychonomic Bulletin & Review'', ''7''(3), 403-423.</ref> An example of articulation suppression is repeating the same word over many times such as '''the''<nowiki/>' 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.<ref name=Speech3/>

==Schizophrenia and subvocalization==
People with [[schizophrenia]] known to experience auditory [[hallucination]]s could show the result of over-activation of the muscles in the larynx.<ref name=schizophrenia>Green, M. F., & Kinsbourne, M. (1990). Subvocal activity and auditory hallucinations: Clues for behavioral treatments?. ''Schizophrenia Bulletin'', ''16''(4), 617-625.</ref> Using an electromyography to record muscle movement, individuals experiencing hallucinations showed greater muscle activation before these hallucinations occurred.<ref name=schizophrenia/> However, this muscle activation is not easily detected which means the muscle movement must be measured on a wider range.<ref name=schizophrenia/> Though a wider range is needed to detect the muscle movement, it is still considered as subvocalization. Much more research is needed to link subvocalization with hallucination but many schizophrenics report "hearing voices" (as hallucinations) coming from their throat.<ref name=schizophrenia2>Smith, J. D., Wilson, M., & Reisberg, D. (1995). The role of subvocalization in auditory imagery. ''Neuropsychologia'', ''33''(11), 1433-1454. {{doi|10.1016/0028-3932(95)00074-D}}</ref> 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.<ref name=schizophrenia/>

==References==
{{Reflist}}

==External links==
{{wikibooks|Speed reading}}
*[http://www.nasa.gov/home/hqnews/2004/mar/HQ_04093_subvocal_speech.html NASA Develops System to Computerize Silent, 'Subvocal Speech' ]
*[https://web.archive.org/web/20060426023824/http://www.forbes.com/free_forbes/2006/0410/084.html?partner=yahoomag NASA researchers can hear what you're saying, even when you don't make a sound ]
*[https://web.archive.org/web/20070115091615/http://www.tfot.info/content/view/80/58/ An interview with NASA's Chuck Jorgensen on the Subvocal Speech] – including pictures and video of the technology. Copy at [https://web.archive.org/web/20080526153659/http://www.tfot.info/articles.php?itemId=28%2F58%2F Archive.org] (no pictures/video)

[[Category:Reading (process)]]
[[Category:Human communication]]
[[Category:Educational psychology]]
[[Category:Learning to read]]
[[Category:Memory]]
[[Category:Vocal skills]]