Sign Language Phonology: Parameters, Holds, and Movement

Phonological processes are systematic changes in how signs or sounds are formed based on their linguistic context. These changes occur when signs are produced in sequence with other signs, affecting pronunciation without changing meaning. In English, examples include the flap T sound in 'waiter' instead of a stop T, and the deletion of the middle vowel in informal speech (family → fam-lee). Native speakers automatically apply these processes, though some are obligatory while others are optional depending on formality level. This foundational concept applies across spoken and signed languages.

This section presents key phonological processes observed in sign language production. Deletion involves omitting phonemes during sign production, similar to spoken language errors where children might say 'pato' instead of 'prato.' Metastasis involves alternation in movement direction, where hearing learners often confuse forward (future) and backward (past) movements. Inclusion involves expanding minimum units through repetition, representing natural variation rather than error. These processes demonstrate that phonological phenomena operate similarly across spoken and sign languages, with deletion and metastasis being particularly common in non-fluent production. The research identified these patterns through detailed frame-by-frame analysis using software tools.

Phonological rules should be evaluated based on simplicity and naturalness. Common processes include: assimilation (sounds become more similar to neighboring sounds, e.g., 't' becomes flap [ɾ] between voiced sounds), dissimilation (sounds become less similar, e.g., 'fair' pronounced as [fɛr]), deletion (omission of sounds in specific environments, e.g., schwa deletion before stressed syllables), epenthesis (insertion of sounds, e.g., schwa in 'between'), and metathesis (change in order of segments). A good rule should be as general as data permits, applying to natural classes of sounds sharing common features rather than random collections.

Phonological processes are mechanisms through which sound changes occur in languages. The major processes introduced include: assimilation (sounds becoming more similar to nearby sounds), dissimilation (sounds becoming less similar to nearby sounds), insertion/apposition (adding sounds), deletion/ellipsis (removing sounds), and metathesis (changing the order of sounds). Among these, assimilation is the most common phonological process across all languages. These processes operate within the rapid flow of normal speech, modifying the features of sounds in a language's phonological system. Understanding these processes helps explain why and how sounds change in predictable ways across different languages and dialects.

Five major types of phonological processes modify speech sounds: (1) Assimilation - one segment adopts features of an adjacent segment (e.g., /n/ taking vowel qualities); (2) Dissimilation - segments differentiate themselves from similar neighbors; (3) Deletion - segments present mentally are omitted in speech; (4) Insertion - extra segments are added for easier pronunciation; (5) Metathesis - consonants swap positions. These processes occur naturally in all languages and vary by speaker and context. Examples include saying 'inver-tir' instead of 'invertir' (assimilation), 'reventando' instead of 'reventando' (insertion), and 'ejecutando' instead of 'ejecutando' (metathesis).

Sign language morphology encompasses various sign formation processes including iconic signs (directly iconic, metonymic, substitutive, virtual), fingerspelling for representing spoken language elements, coinage for personal names, reduplication for creating new meanings, and compounding for forming complex lexical items; grammatical categories include word classes (nouns, adjectives, verbs, adverbs, numerals, classifiers), and morphological markers such as person, number, gender, tense, and aspect, which are expressed through spatial parameters like hand orientation, movement direction, and location in signing space rather than phonological changes.

Sign language morphology is built from four contrastive formational features: hand configurations, locations, movements, and non-manual features. These components create morphological patterns through: (1) Verb directionality - spatial modification of verb signs to mark subject-object roles; (2) Classifier constructions - rich signs where each component represents specific meanings; (3) Reduplication - repetition to mark number or aspect; (4) Affixation - combining signs to create new meanings. The paradox of sign language morphology emerges because these complex systems appear in relatively young languages, challenging traditional views of morphological development timelines.

This section explores morphological and phonological features of NGT. Morphology includes verbal aspect expressed through spatial location (creating a location in space to represent past events), and plural formation through sign repetition. Phonology examines the components of signs: handshape, movement, location, and non-manual features. The video demonstrates how changing any component of a sign alters its meaning, similar to sound changes in spoken language. For example, changing handshape from 'week' to 'paal' changes meaning from 'last week' to 'pole'. This shows NGT has a systematic phonological structure where small changes produce systematic meaning changes.

Sign languages have five fundamental phonological parameters that work together to form complete signs: (1) Hand Configuration (configuração de mãos) - the shape of the hand, (2) Point of Articulation (ponto de articulação) - where in space the sign is produced, (3) Movement (movimento) - the path and type of motion, (4) Orientation (orientação) - the direction the hand is facing, and (5) Non-manual Markers (expressões não manuais) - facial expressions and body language. These parameters are analogous to phonemes in spoken languages, but instead of being based on sound, they are based on visual-gestural elements. The term 'quirema' refers to the hand units in sign languages, derived from the Greek word 'kheir' meaning hand. Signs are constructed by combining these parameters, and changing one parameter can change the meaning of a sign.

Learning a second language requires different neural accommodations depending on whether it is an auditory language or a manual/visual-spatial language like American Sign Language. Sign language is visual-spatial in nature, requiring simultaneous perception of hand configuration, location, and movement—shifting from serial auditory processing to parallel visual processing. Auditory languages require adjusting to different speech sounds. Despite these differences in sensory input processing, the language comprehension mechanisms may be similar once the perceptual signals are properly interpreted.

Language processing involves distinct sensory pathways converging on specialized cortical areas. Visual language processing follows a route from eyes through optic nerve to occipital visual cortex, then to angular gyrus and finally to Wernicke's area for decoding. Auditory processing travels via vestibulocochlear nerve to temporal auditory cortex, then directly to Wernicke's area. Both pathways transform sensory input into neural representations. These representations must then travel through the arcuate fasciculus to Broca's area for motor transformation into speech, completing the language processing circuit.

The adult brain contains specialized regions for language processing that are distinct from those used for mathematics, music, or social inference. Language is not localized to a single organ but distributed across a network including the left frontal cortex and left lateral temporal cortex. While most people show left-hemisphere lateralization, some exhibit bilateral responses or right-hemisphere dominance, particularly among left-handed individuals. This network responds robustly to linguistic input regardless of whether it is visual or auditory.

Language processing involves distinct visual and auditory pathways. Visual input enters primary occipital lobes (V1, V2) and progresses through the lateral occipital area to the fusiform gyrus, containing the visual word form area specialized for linking visual objects to names and orthographic decoding. This area activates ~150ms after word appearance and responds preferentially to meaningful words. The inferior longitudinal fasciculus carries information from occipital to temporal lobes. Auditory processing involves phonemes classified by motor gestures: stops/plosives, fricatives, nasals, and vowels. The superior temporal gyrus encodes acoustic features with anterior regions processing vowel timing and posterior regions detecting phrase boundaries. Heschl's gyrus and planum temporale in the Sylvian fissure are critical for phonological perception. Pure word deafness results from bilateral superior temporal gyrus lesions, causing inability to recognize spoken words despite intact written comprehension.

Beyond the shared core language network, sign and speech processing show modality-specific differences. Auditory cortex activates more during spoken language processing, while visual motion processing areas activate more during sign language processing. Critically, the parietal lobe shows enhanced recruitment for sign language, particularly when processing spatial relationships. This reflects the unique spatial demands of sign language and demonstrates how different sensory modalities engage distinct neural resources even for the same linguistic function.

Glossing uses capitalized words to represent signs, following grammatical structure. Conventions include hyphens for multiple words representing one sign, and symbols for features like head nod and placement. Other systems like Hamberg notation and SignWriting attempt to show hand shapes, orientation, and movement but are complex and rarely used. The digital revolution has made these older systems less necessary.

Sign languages are analyzed using articulatory phonetics principles similar to spoken languages, with the HamNoSys system providing a detailed transcription framework that decomposes signs into six components: hand shape (finger configurations), hand direction and orientation (where palms point and rotate), relationship between hands (symmetry, contact), motion (trajectory and angles), location (body position), and non-manual features (facial expressions, mouth movements); unlike spoken languages which primarily use the International Phonetic Alphabet (IPA), sign languages lack a universally agreed-upon transcription system, though HamNoSys offers comprehensive narrow transcription capabilities.

William Stokoe developed the first notation system for American Sign Language in his 1960 book 'Sign Language Structure.' His model divides every sign into three simultaneous components: Location (where the sign is produced), Handshape (the configuration of the hand), and Movement (how the hand moves). Unlike spoken languages where words are built from sequential segments like consonants and vowels, Stokoe's system treats these three components as a bundle that exists simultaneously. Each sign is described using specific lists of locations, handshapes, and movements combined together. This system was widely accepted for over 20 years but proved inadequate for describing grammatical processes like compounding and inflection.

Sign languages have a structured phonological system including handshape (configuração de mão), location (localização), movement (movimento), orientation (orientação das mãos), and facial expressions. These components function similarly to how sounds work in spoken languages, allowing for systematic and organized expression.

SignWriting is a direct writing system for sign languages developed by Val in 1974 that allows direct transcription without passing through another language. It registers visual gesture forms like photographs using approximately 950 symbols stacked vertically with spaces between them. The system adapts to any sign language worldwide because it directly transcribes gesture forms without requiring prior knowledge of specific gestures. It has been adopted in over 40 countries including Brazil (since 1996), France, England, United States, and Finland. Sign languages are composed of five linguistic parameters: Configuration (handshape) proposed by Stokoe, Location where hands move in space, Orientation (palm direction) added by Battison, Movement how hands move, and Expression (non-manual components including facial expressions) added by Liddell and Johnson. These parameters were systematically named using terminology proposed by Capovilla and Garcia. SignWriting represents each parameter: Configuration through handshape symbols, Location through spatial location indicators, Orientation through color coding (white/black), Movement through arrows and directional symbols, and Expression through facial expression symbols.