MIT Encyclopedia of the Cognitive Sciences - Cryptome

638 Phonological Rules and Processes
the various Indo-European languages. In the twentieth century,
attention shifted to a synchronic perspective, prompted
by observations such as Edward SAPIR’s that as part of their
grammatical competence mature speakers unconsciously and
effortlessly assign (sometimes radically) different pronunciations
to a lexical item drawn from memory and inserted in
different grammatical or prosodic contexts. For example, in
the pronunciation of the word átom American English speakers
“flap” the intervocalic consonant to [2] and reduce the
unstressed vowel to schwa [E] so that it merges with Adam:
['æ2Em]. The underlying phonemes emerge when the stress is
shifted under affixation: atóm-ic [Et h 'am-Ik]. Processes also
figure in the neutralizations found in child language such as
the loss of the tongue-tip articulation of r so that room
merges with womb.
Phonological processes fall into two broad categories:
sound change and prosodic grouping. We briefly illustrate
each type. In in-articulate versus im-possible the prefixal
nasal assimilates the labial feature of the [p] thereby changing
from [n] to [m]. Dissimilation alters neighboring sounds
that share the same feature so that they become more distinct
from one another (see DISTINCTIVE FEATURES). For
example, the vocalic nucleus and offglide comprising the
[au] diphthong of how share a retracted tongue position in
most English dialects. In broad Australian English the
nucleus is fronted to the [æ] vowel of cat: h[æu]. Assimilation
and dissimilation are subject to a strict locality condition
requiring that they apply in the context of the closest
sound with the appropriate feature. The phonological features
that define a sound are also subject to deletion and
insertion: the former typically operates in prosodically
weak contexts (reduction of unstressed vowels to schwa in
át[E]m but [E]tóm-ic) and the latter in strong contexts (aspiration
of [t] before stress in a[t h ]ómic).
Processes of prosodic grouping include the organization
of phonemes into syllables. In English a consonant cluster
such as [rt] easily combines with the preceding vowel into a
single syllable: monosyllabic mart. But in order to syllabify
the inverse cluster [tr], a helping schwa is required: disyllabic
me.t[E]r (cf. metr-ic). Languages such as Japanese
have simpler syllabic structures that bar syllable-internal
consonant clusters and place rigid restrictions on syllablefinal
consonants. Accordingly, the [rt] cluster in a loanword
such as French courte [kurt] ‘short’ receives two extra syllables
when it is adapted into Japanese: kuruto (Shinohara
1997). At the next level of prosodic organization, syllables
are grouped into strong-weak (trochaic) or weak-strong
(iambic) rhythmic units known as metrical feet. Native Australian
languages impose trochaic rhythm so that words
have a canonical SsSsSs . . . syllabic structure in comparison
to the iambic grouping sSsSsS . . . found in many Native
American languages. English has trochaic grouping as
shown by the strong-weak template imposed on nickname
formation: Elízabeth shortens to Ss Lísa; sS Elí is impossible.
Some linguists (e.g., Stampe 1979) distinguish between
“processes” that reflect phonetically motivated limitations
on which sounds can appear where in pronunciation and
more arbitrary and conventional “rules” that are typically
restricted to particular morphological or lexical contexts
such as the voicing of [f] in the plural of leaf: leaves but
reefs (*reeves) and verbal he leafs (*leaves) through the
paper). A plausible but unsubstantiated hypothesis is that
rules relate different lexical items stored in memory while
processes operate online.
Phonological processes are often phonetically motivated,
seeming either to enhance the perceptibility of a sound,
especially in “strong” contexts or more formal speaking
styles (aspiration of prestressed [t] in a[t h ]ómic), or to minimize
articulatory gestures, especially in “weak” contexts or
fast tempos (flapping of the stop and reduction of the
unstressed vowel of átom ['æ2Em]). Besides a typology
based on their formal properties, phonological processes are
also usefully viewed as different solutions to a common
phonetic difficulty. For example, the transition from the
nasal to the fricative in the consonant cluster of dense is relatively
complex because it requires synchronization of two
independent gestures: raising the velum to shut off nasal airflow
and shifting the tongue tip from a closure to a constriction.
Common responses include insertion of a transitional
stop den[t]se (to rhyme with dents) or deletion of the
tongue-tip closure d[ε ~ ]s. An example from prosody is provided
by the widespread tendency to avoid syllables beginning
with a vowel. When morphological or syntactic rules
juxtapose vowels, a variety of processes come into play to
avoid a syllable break between the vowels. These include
deletion of one of the vowels (Slavic), contraction of the
vowels into a diphthong (Polynesian) or long vowel (Sanskrit),
or insertion of a consonantal onset (British English
intrusive [r] as in the idea [r] is).
Processes are characteristically myopic in the sense that
in solving one phonetic problem they often create another.
Popular London (Cockney) deletion of initial [h] creates a
vowel cluster with the indefinite article (“a hedge” [E 3d^)—
a situation that is otherwise avoided by substitution of the
an allomorph (cf. “an edge” [En 3d^]; Wells 1982). To take
another example (data from Bethin 1992), in Polish [n]
assimilates the place of articulation of a following velar:
ba[n]k ‘bank’. In the Southwestern dialect, the process is
extended to clusters arising from the deletion of a weak
vowel, whereas in the Northeastern dialect, such derived nk
clusters remain unassimilated: ganek ‘porch’, ga[n]ka SW
versus ga[n]ka NE genitive singular. Many phonologists
(e.g., Halle 1962) conclude from examples like this that processes
apply in a linear sequence: in the Southwestern dialect,
vowel deletion precedes nasal assimilation, whereas in
the Northeastern dialect, nasal assimilation precedes vowel
deletion (and so sees /ganek+a/ at its point of application).
An alternative interpretation (Donegan and Stampe 1979)
sees all processes as applying simultaneously to the input
with each given the option to iterate (Southwestern) or not
(Northeastern).
Although myopic, phonological processes are typically
not self-defeating in the sense of recreating the same problem
they are called upon to solve. An example is provided
by the liquid [l,r] dissimilation inherited from Latin (Steriade
1995), in which the suffixal [l] of nav-al, fat-al, mor-al
is turned into [r] when the stem contains an [l]: stell-ar, lunar,
column-ar, nucle-ar. The process systematically blocks
when an [r] intervenes between the suffixal and stem [l]'s: