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The McGurk effect is a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. The illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound. The visual information a person gets from seeing a person speak changes the way they hear the sound. People who are used to watching dubbed movies may be among people who are not susceptible to the McGurk effect because they have, to some extent, learned to ignore the information they are getting from the mouths of the "speakers". If a person is getting poor quality auditory information but good quality visual information, they may be more likely to experience the McGurk effect. Integration abilities for audio and visual information may also influence whether a person will experience the effect. People who are better at sensory integration have been shown to be more susceptible to the effect.〔 Many people are affected differently by the McGurk effect based on many factors, including brain damage and other disorders. ==Background== It was first described in 1976 in a paper by Harry McGurk and John MacDonald titled "Hearing Lips and Seeing Voices". This effect was discovered by accident when McGurk and his research assistant, MacDonald, asked a technician to dub a video with a different phoneme from the one spoken while conducting a study on how infants perceive language at different developmental stages. When the video was played back, both researchers heard a third phoneme rather than the one spoken or mouthed in the video.〔"Haskins Laboratories">(【引用サイトリンク】url=http://www.haskins.yale.edu/featured/heads/mcgurk.html )〕 This effect may be experienced when a video of one phoneme's production is dubbed with a sound-recording of a different phoneme being spoken. Often, the perceived phoneme is a third, intermediate phoneme. As an example, the syllable /ba-ba/ is spoken over the lip movements of /ga-ga/, and the perception is of /da-da/. McGurk and MacDonald originally believed that this resulted from the common phonetic and visual properties of /b/ and /g/. Two types of illusion in response to incongruent audiovisual stimuli have been observed: fusions ('ba' auditory and 'ga' visual produce 'da') and combinations ('ga' auditory and 'ba' visual produce 'bga'). This is the brain's effort to provide the consciousness with its best guess about the incoming information.〔O’Shea, M. (2005). ''The Brain: A Very Short Introduction.'' Oxford University Press〕 The information coming from the eyes and ears is contradictory, and in this instance, the eyes (visual information) have had a greater effect on the brain and thus the fusion and combination responses have been created.〔 Vision is the primary sense for humans,〔 but speech perception is multimodal, which means that it involves information from more than one sensory modality, in particular, audition and vision. The McGurk effect arises during phonetic processing because the integration of audio and visual information happens early in speech perception.〔 The McGurk effect is very robust; that is, knowledge about it seems to have little effect on one's perception of it. This is different from certain optical illusions, which break down once one 'sees through' them. Some people, including those that have been researching the phenomenon for more than twenty years, experience the effect even when they are aware that it is taking place.〔〔Rosenblum, L. D. (2010). ''See what I'm saying: The extraordinary powers of our five senses''. New York, NY: W. W. Norton & Company Inc.〕 With the exception of people who can identify most of what is being said from speech-reading alone, most people are quite limited in their ability to identify speech from visual-only signals.〔 A more extensive phenomenon is the ability of visual speech to increase the intelligibility of heard speech in a noisy environment.〔 Visible speech can also alter the perception of perfectly audible speech sounds when the visual speech stimuli are mismatched with the auditory speech.〔 Normally, speech perception is thought to be an auditory process,〔 however, our use of information is immediate, automatic, and, to a large degree, unconscious〔 and therefore, despite what is widely accepted as true, speech is not only something we hear.〔 Speech is perceived by all of the senses working together (seeing, touching, and listening to a face move).〔 The brain is often unaware of the separate sensory contributions of what it perceives.〔 Therefore, when it comes to recognizing speech the brain cannot differentiate whether it is seeing or hearing the incoming information.〔 It has also been examined in relation to witness testimony. Wareham and Wright's 2005 study showed that inconsistent visual information can change the perception of spoken utterances, suggesting that the McGurk effect may have many influences in everyday perception. Not limited to syllables, the effect can occur in whole words〔 and have an effect on daily interactions that people are unaware of. Research into this area can provide information on not only theoretical questions, but also it can provide therapeutic and diagnostic relevance for those with disorders relating to audio and visual integration of speech cues. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「McGurk effect」の詳細全文を読む スポンサード リンク
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