MOTOR EQUIVALENCE The central element of the motor theory of language
MOTOR EQUIVALENCE (with the underlying motor basis of perception) To convert: an action into equivalent action word into action action into word word into gesture gesture into word word into sound sound into word visual percept into word visual percept into gesture
WORD SOUND/MEANING CATEGORIES The sound-structure of a word can represent the meaning of the word in a number of ways: • Most straightforwardly the word can sound like its meaning. Examples: hiss, wail, sigh, cuckoo, tick-tock, ding-dong. • A word can generate indirectly a sound representing what the word means. The names of many animals are in this category with other words referring to things which produce sounds. Examples: cat, dog, wolf, wasp, bell, whistle, klaxon, thunder, wind. • A word can directly reproduce the action to which it refers. Examples: spit, suck, chew, yawn, sneer.
A word can generate a deictic gesture, that is, a gesture which involves pointing to what the word refers to. Words for many body parts and some pronouns are in this category. Examples: head, ear, eye, you, he. • A word can generate an action which represents what the word refers to. This is similar to deictic words. Many function words fall in this category as well as many simple action verbs. Examples: this, that, at, forward, back, hit, throw, take, push, point, pluck, pick, sew, heavy, light. • A word may generate a gesture which outlines what the word refers to. Examples: arch, edge, heap. • A word may generate an action picturing the use of an object referred to. Example: needle,
A word may generate a picturing action plus an associated sound. Examples: whip, air, fire. • A word may generate a gesture which amounts to the 'showing' of what the word refers to. This is particularly the case for body parts. Examples: hand, arm, elbow, wrist. • A word may generate a deictic gesture plus an action gesture. Examples: hat, flower. • A word may generate a complex containing visual, sound, deictic or other elements. Examples: snake, rain. • A word may generate an internal feeling or action. Words for emotions seem to come in this category. Examples: bitter, sweet, sour, sad, angry, cheerful.
A word may generate an action or an internal feeling for an abstract, non-concrete meaning. Examples: remember, understand, know. The associated actions may metaphorically represent the meaning e.g. elevate, separate, grasp, spontaneous. • A word may generate a movement or position specifically referring to an aspect of time. Examples: now, then • Click to see Illustrative List of words where the sound/meaning relation falls in one or other of the above categories.
The neural basis of the word sound/meaning equivalences is explained in terms of the Motor Theory of Language and of the integration of Perception and the Motor System.
MOTOR THEORY OF LANGUAGE The Motor Theory is a theory of the origin and functioning of language. The theory is that the structures of language (phonological, lexical and syntactic) were derived from and modelled on the pre-existing complex neural systems which had evolved for the control of body movement. Motor control at the neural level requires pre-set elementary units of action which can be integrated into more extended patterns of bodily action -- neural motor programs. Speech is essentially a motor activity (a stream of articulatory gestures). Language made use of the elementary pre-set units of motor action to produce equivalent phonological units (phonemic categories). The neural programs for individual words were constructed from the elementary units in the same way as motor programs for bodily action. The syntactic processes and structures of language were modelled on the motor ‘syntax’.
PROPOSITIONS 1. There are basic (innate) elementary neural motor programs from which all bodily movements are constructed 2. These elementary motor programs control all the precise ballistic and targeted movements of the hand and arm 3. The elementary programs when redirected to the articulatory organs produce an equivalent set of elementary speech sounds (elementary articulatory gestures) 4. Every articulatory program can be redirected (through motor equivalence) to produce an equivalent movement of the hand and arm 5. Gestures of the hand and arm are structured by the contours of perceived objects or of larger bodily actions 6 Every gesture structured by a perceived object or action can be redirected to produce an equivalent articulatory action
PROPOSITION 1 1. There are basic (innate) elementary neural motor programs from which all bodily movements are constructed "Both the effects of simplifying the dynamics computation and the limitations of feedback control in biological arms ... strongly suggest that there must exist substantially correct preprograms in order for humans to make accurate fast arm movements."(Hollerbach 1985: 140) "A Vocabulary of Motor Acts. ... We propose that in inferior area 6 there is a vocabulary of elementary motor acts coded at the single neuron level. This vocabulary is essentially related to arm-mouth movements." (Rizzolatti and Gentilucci 1988: 281) "Movement plans may be complex in the sense of being composed of separable component tasks. These components may be coordinated at some level by the voluntary motor system, in order to combine tasks into appropriate actions ." (Haggard 1991: 153) “these methods have established that all natural movements are organized in discrete segments. . . . So movement is organized on the basis of a repertoire of synergies which go to form possible actions. . . . A library of movements ready to be executed” “ces méthodes ont permis de constater que tous les mouvements naturels sont organisés en segments discrets. . . . Le mouvement est donc organisé à partir d'un répertoire de synergies qui compose autant d'actes possibles. ... une bibliothèque de mouvements facilement déclenchables” (Berthoz 1997: 152, 176)
PROPOSITION 3 3. The elementary programs when redirected to the articulatory organs produce an equivalent set of elementary speech sounds (elementary articulatory gestures) Articulatory phonology takes seriously the view that the units of speech production are actions, and therefore that they are dynamic, not static. (Haskins Laboratories) “Utterances are modeled as organized patterns ... of gestures, in which gestural units may overlap in time. The phonological structures defined in this way provide a set of articulatorily based natural classes” (Browman and Goldstein 1992: 155) “Such gestures not only can characterize the movements of the speech articulators but also can act as phonological primitives” (Browman and Goldstein 1990: 313)
PROPOSITION 4 4. Every articulatory program can be redirected (through motor equivalence) to produce an equivalent movement of the hand and arm MOTOREQUIVALENCE "On désigne par 'équivalence motrice' une propriété simple et remarquable du cerveau: celle qui permet de faire le même mouvement avec des effecteurs très différents. Par exemple, je peux écrire le lettre A avec le main, ou le pied, ou même la bouche; je peux même dessiner un A en me promenant sur le plage! “(Berthoz 1997: 246) “ ‘Motor equivalence’ is the term for a simple and remarkable property of the brain which allows one to perform the same bodily movement with very different effector systems. For example, I can write the letter A with my hand, with my foot, or even with my mouth; I could even make an A by walking on the beach” (Berthoz 1997: 246) "comparing findings on the motor organization of speech with the organization of voluntary movements about the elbow ...We have found that the kinematic patterns for movements of the tongue dorsum were similar to those of voluntary flexion-extension movements about the elbow" (Ostry and Cooke 1987: 223). "the task dynamic model we are using for speech was exactly the model used for controlling arm movements, with the articulators of the vocal tract simply substituted for those of the arm." (Browman and Goldstein 1991: 314)
PROPOSITION 5 5. Gestures of the hand and arm are structured by the contours of perceived objects or of larger bodily actions "While people talk, they also use their hands. 'illustrative gestures' are used to indicate shapes, sizes, directions and to point, for example to describe a spiral staircase. .. Where illustrative gestures are similar in form to their reference, emblems [gestures with arbitrary meanings] usually are not" (Argyle 1987:63) A gesture may be an indication. This is perhaps not so much resemblance as a variant of the action-gesture. The most rudimentary gesture is to point to the object referred to or more particularly to the feature of the body referred to. A gesture for the ear is to point to or touch the ear - and so on. "We respond to gestures with an extreme alertness and, one might almost say, in accordance with an elaborate and secret code that is written nowhere, known by none and understood by all." (Sapir quoted by Plutchik 1980: 269) “Iconic gestures appear to be images of concepts and imply the existence of schemas which produce them” (McNeill 1981: 203)
PROPOSITION 6 6 Every gesture structured by a perceived object or action can be redirected to produce an equivalent articulatory action GESTURE AND SPEECH AS LINKED PROCESSES "speech and gesture arise as interacting elements of a single system” (McNeill 1987: 503) "The central thesis is that the visual system and the motor system are functionally inseparable ... they are components of a unified perceptuo-motor system, which is itself a component of the organism-environment system." (Lee 1980: 281) “Visually directed action implies continuous transformation of incoming visual stimuli into motor commands.” (Jeannerod 1986: 41)