Perfect bilingualism is uncommon. One language is usually more dominant than the other.
Most bilingual communities have one thing in common, i.e. a fairly clear functional differentiation of the two languages in respect of speech situations known as domains.
Code-switching: a bilingual speaker often uses two languages alternatively during a conversation with another bilingual speaker.
[F] Ethnic dialect àBlack English Vernacular (BEV)
Ethnic dialect: a social dialect of a language, often cutting across regional differences
BEV: spoken mostly by a large section of non-middle-class American blacks. It is stigmatized as bad English, a purely social attitude that has no linguistic basis.
The social environment of BEV:
The distinctive features of BEV persist not for racial reasons, but for social, educational, and economical reasons.
Speaker of an ethnic dialect like BEV regard the language they speak the major symbol of their socio-cultural identity.
Some features of BEV:
① phonological characteristics: The frequent simplification of consonant clusters at the end of words when one of the two consonants is an alveolar /t/, /d/, /s/, or /z/; the l-deletion rule; the deletion of some word-final stop consonants in words like “side” and “borrowed”;
② syntactical characteristics: the frequent absence of the copula “be”; the systematic use of the expression “it is” where SE uses “there is” in the sense of “there exists”; the use of double negation constructions.

[G] Social dialect
Varieties of language used by groups defined according to class, education, age, sex, and a number of other social parameters
Overt prestige v. covert prestige
① Educational varieties
One extreme form of the educational influence on the way one speaks is the fact that some college professors talk like a book.
Lower class and less educated: [n] rather than [N]
[h]-dropping
② Age varieties
Lexical variation according to the age correlates with time periods is more noticeable across three-generation time span.
Old people tend to be more conservative than the younger generation
③ Gender varieties
Female speakers tend to use more prestigious forms than male speakers with the same general social background:
a) Females are politer in conversation;
b) the difference of speech acts (the frequent use of polite formulas in female speeches)
The choice of words in terms of grammatical gender is sexist: use of “he” to refer to either sexes or unknown or irrelevant
The sexist bias is also rooted by the way neutral terms are interpreted.
Governor/governess |Master/mistress |Career woman/man
English is one such language whose gender terms are heavily asymmetric in morphological representation. Male terms get unmarked and the female term is often marked by adding a bound morpheme, or by compounding.
Feminist movement, use more gender-neutral expressions
④ Register varieties (situational dialects)
Register: one language variety appropriate for use in particular speech situations, in contrast to language varieties that are associated with the social or regional grouping of their customary users.
Speech variation in register may be carried over into the written language.
⑤ Address terms
Address term: or address form, refers to the word or words used to address somebody in speech or writing.
Common English address terms:
First name
Last name
Title+ last name
Title alone
Kin term: Dad, mummy etc.
⑥ Slang
Slang: a casual use of language that consists of expressive but nonstandard vocabulary, typically of arbitrary, flashy and often ephemeral coinages and figures of speech characterized by spontaneity and sometimes by raciness.
Purpose: a desire for novelty, for vivid emphasis, for membership in a particular group or class, for being up with the terms of a little ahead
Negative connotation: a low or vulgar form of language
In-group language or community jargon
⑦ Linguistic taboo
Linguistic taboo: refers to a word or expression that is prohibited by the polite society from general use.
Obscene, profane, and swear words
Many languages contain two words or expressions with the identical linguistic meaning, with one acceptable and the other a cause of embarrassment or horror.
The avoidance of using taboo: language mirrors social attitudes, emotions and value judgment, and has no linguistic basis.
⑧ Euphemism
Euphemism: a mild, indirect or less offensive word or expression substituted when the speaker or writer fears more direct wording might be harsh, unpleasantly direct, or offensive
Death or dying, ask for location of the “bathroom” etc.
Often when the negative connotation of a word is recognized in its euphemistic form, a new euphemism will have to be sought for.
Toilet, WC, powder room, Men’s Room, Ladies’ Room, Gentlemen, bathroom, restroom
As long as there is a need to avoid the use of taboo language, there is a need for the use of euphemistic substitutes

Chapter 12  Psycholinguistics
The study of language in relation to the mind
P.S. some of the following discussed sometimes fall into the scope of neurolinguistics and sociolinguistics, esp. concerning the structure of the brain.
[A] The biological foundations of language
Human linguistic ability largely depends on the structure and dynamics of the human brain, rather than, the structure of the vocal cords.
Neuronsàcerebral cortexàhemisphere
Brain lateralization (specific to human beings): the left hemisphere has primary responsibility for language, while the right hemisphere controls visual and spatial skills as well as the perception of nonlinguistic sounds and musical melodies.
The localization of cognitive and perceptual functions in a particular hemisphere of the brain is called lateralization.
[B] Linguistic lateralization
Left hemispheric dominance for language, this hypothesis has been proved by Dichotic listening research（两耳分听试验）
The sound presented in the right ear goes directly to the left brain. The sound heard in the left ear, on the other hand, must first go to the right hemisphere, from where it is transferred to the left side of the brain for processing.
Right ear advantage:（右耳优势）it appears to exist primarily for linguistic stimuli, both meaningful and nonsensical.
[C] The language centers
① Broca’s area (French surgeon and anatomist): The frontal lobe in the left cerebral hemisphere damaged extreme difficulty in producing speech;
[Speech production deficit] word-finding difficulties and problems with syntax
② Wernicke’s area (German physician, 1874): Strengthened Broca’s claim, and generated intense interest in the hypothesis that different areas within the left hemisphere fulfill different linguistic functions
[Speech comprehension deficit] difficult in understanding speech (posterior speech cortex)
③ The angular gyrus（角形脑回）: It is responsible for converting a visual stimulus into an auditory form and vice versa
The word is heard and comprehended via Wernicke’s area. This signal is then transferred via the arcuate fasciculus to Broca’s area (the angular gyrus), where preparations are made to produce it. A signal is then sent to the motor cortex to physically articulate the word.
④ language perception, comprehension and production
[D] The critical period for language acquisition ß neurobiologist Eric Lenneberg
It refers to a period in one’s life extending from about two to puberty, during which the human brain is most ready to acquire a particular language and language learning can proceed easily, swiftly, and without explicit instruction.
Language faculty of an average human degenerates after the critical period.