Speech Perception Motor Theory Of See Speech Theories

SPEECH THEORIES. A major research issue behind speech theories is the question of why speech is so much easier to acquire than reading and writing skills. One answer is that speech is easy because humans have evolved specialized neural mechanisms (affording a biological advantage) for perceiving and producing it. The heart of this argument is that speakers are endowed with a brain module specialized for controlling the production of speech gestures - the intricate patterns of movement of the vocal tract allowing one to produce the sounds of one's language. A more controversial corollary of this view is that the perception of speech depends, also, on specialized neural structures that automatically transcode speech that one hears into a code for the gestures that were responsible for articulating it. According to this view, the process of gaining access to the small segments of speech (called "phonemes") is difficult because phonemes are only abstractions from a more fundamental motor code. Thus, a child may learn to speak adequately without access to the nature of the motor code underlying the perception and production of speech. On the other hand, in learning to read, the child is required to develop an explicit understanding of phonemes that may be considered to be a difficult or "unnatural" task. The American speech/reading scientist and psycholinguist Alvin Meyer Liberman (1917-2000) was instrumental in the development and research of the modern motor theory of speech perception. The early motor theory of speech perception (the conventional theory or "horizontal view") states that - in perceiving language -one recovers in the acoustic information how the sound was produced during articulation [cf., Tadoma method/effect (a portmanteau word named after two deaf-blind children Tad Chapman and Oma Simpson who were the first to use the method in the early 1960s in the United States, even though the effect was known in the 1890s in Nor-way) - allows an individual who is both deaf and blind to receive/interpret speech by placing his/her thumb lightly in contact with the speaker's lips and the fingers of the same hand on the speaker's jaw and neck; in this way, the deaf-blind individual may detect via touch the pattern of airflow from the speaker's nose and mouth, as well as the articulatory movements in vibrations from the speaker's vocal tract

(cf., phonatory theory - concerns speech and voice production where the movements and the vocal cords, caused by the breath pressure, determine the intensity, pitch, and quality of the voice); the Tadoma method is similar, in principle, to the teletactor - a device for deaf individuals that converts sound waves into vibrations that may be sensed tactually on the skin, and the optacon/optohapt - an electronic device for blind persons that transforms a pattern of light-intensity differences into a pattern of vibrations that is felt by one's fingertips, or a device that converts printed text into vibrations that are transmitted to various parts of the body and, thereby, allows the person to "read"]. Liberman's approach is based on the notion that there are no acoustic invariants that are tied directly to the perception of the sound (the relevant information concerning the articulation may be in a neighboring sound, as well as being dependent on the context in which the sound occurs). The more modern, or revised, motor theory of speech perception (the "vertical view") adds the fiat that there is a specific cognitive "module" for speech perception that is separate from other auditory perception mechanisms. In one associative hypothesis, the specific-module is in a "serial architecture" with the general-module, with the speech-module preceding the general-model, and where the processing in the speech-module is not passed on to the general-module. The "module" in Liberman's model is comparable to other modules in nature, such as that which enables an animal to localize sound. Peculiar to the phonetic-module is the relation between perception and production, and the fact that it must compete with other modules for the same stimulus variations. Another view - the constructivist hypothesis for speech production - claims that each child must work out the speech gestures and their relation to acoustic patterns anew, and is based on feedback from the child's own production practice ("babbling") as well as the perception of the speech of others (cf., telegraphic speech - the normal speech of children at about the age of two to three years in which the majority of utterances are only three or four words in length, such as "mommy cook eggs" and where functional words - such as articles, pronouns, and conjunctions - are omitted typically). In the earliest recorded psychological experiment (the "Psammetichus experiment"), as reported by the Greek historian Herodotus (c. 485-c. 425 B.C.) in about 429 B.C., the issue of human speech production was investigated. The experiment, performed by the Egyptian pharaoh Psammetichus (664-610 B.C.), attempted to determine whether humans have an innate capacity for speech and, if so, what specific language is innate. The pharaoh ordered that two infants be raised in a remote location by a shepherd who was forbidden to speak in the presence of the infants. After a period of two years, the children began to speak and, in particular, to use the Phrygian word for "bread" over and over again. Based on such results, the pharaoh concluded that the capacity for speech production is innate, and that the "natural language" of humans is Phrygian. See also CHOMSKY'S PSYCHO-LINGUISTIC THEORY; CONSTRUCTIVISM, THEO-RIES OF; EMPIRICIST VERSUS NATIVIST THEORIES; KASPAR HAUSER EFFECT/ EXPERIMENT; LANGUAGE ACQUISITION THEORY; McGURK EFFECT/ILLU-SION; NATURE VERSUS NURTURE THE-ORIES; WHORF-SAPIR HYPOTHESIS/ THEORY. REFERENCES

The motor theory of speech perception revised. Cognition, 21, 1-36. Mattingly, I. G., & Studdert-Kennedy, M.

(Eds.) (1991). Modularity and the motor theory of speech perception. Hillsdale, NJ: Erlbaum. Liberman, A. M. (1996). Speech: A special code. Cambridge, MA: M.I.T. Press. Liberman, A. M. (1998). Why is speech so much easier than reading? In C. Hulme & R. M. Joshi (Eds.), Reading and spelling: Development and disorders. Mahwah, NJ: Erlbaum. Diehl, R. L., Lotto, A. J., & Holt, L. L. (2004).

Speech perception, Annual Review of Psychology, 55, 149-179.

SPENCER'S THEORY OF LAUGHTER/ HUMOR. The English philosopher Herbert Spencer (1820-1903) attempted (like the 16th" century French physician Laurent Joubert) to explain laughter on the basis of physiology and cerebral mechanisms. Spencer's theory of laughter (also called the overflow of nervous energy theory) states that laughter is analogous to the operation of a siphon or pump: it is an overflow (along the most available and ready channels) of "nervous energy" from a reservoir that has been filled up too much. According to this mechanical, energy-release, or hydraulic theory, laughter occurs when we have prepared our minds for something large and meaningful, but what follows actually is something small and insignificant. Thus, Spencer advanced the notion that laughter is similar to nervous energy that is active within any part of the nervous system and that must escape through one or more "channels" that lead to other nerves not connected directly with motor nerves, motor nerves leading to muscular activity, or efferent nerves leading to the viscera. During laughter, the nervous energy escapes via habitual channels: the speech apparatus and the respiratory mechanism. If these channels do not suffice to carry off the amount of energy present, the entire body convulses. Also, according to Spencer's theory, the incongruity involved in the ludicrous or humorous situation must be of a "descending" nature or else the state aroused by the inconsistency would be able to relieve the attendant nervous tension. In the case of an "ascending" type of incongruity, the reaction that is produced (e.g., muscle relaxation) is reciprocally inhibitory or prohibitive to the production of convulsions of laughter. Therefore, according to Spencer's analysis, the ludicrous or humorous must present a situation in which we expect (that is, we are "keyed up") for something great, but in actuality we are confronted/presented with something small. See also DESCARTES' THEORY OF HUMOR/LAUGHTER; FREUD'S THEORY OF PERSONALITY; HUMOR, THEORIES OF; HYDRAULIC THEORY; INCONGRUITY/ INCONSISTENCY THEORIES OF HUMOR; JOUBERT'S THEORY OF LAUGHTER/HUMOR.

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