2 Chapter 1
speech sounds and that teaching them to speak was unlikely given the requisite precise positioning
of the articulators. However, several psychologists believed that given chimpanzees’ manual dex-
terity, a modified sign language might be taught to these primates. They began an intensive sign
language teaching program, and it soon became apparent that humans are not the only creatures
capable of learning and using high- level language. Washoe became so proficient with the modi-
fied sign language that he clearly was capable of using language that went far beyond a simple call
signal system. Since then, many other primates have been taught sign language, and scientists have
discovered that other species, such as whales, dolphins, and bees, use language. It is now accepted
that humans are not the only species with language. However, humans certainly are more profi-
cient and more capable of mastering this remarkable ability than are other species, and language
is one of the likely reasons for our advanced civilization. (For more information on this topic, see
Chomsky, 1980 and Terrace, Petitto, Sanders, and Bever, 1979.)
Defining Language
The definition of language varies greatly among professionals. Authorities from a variety of
disciplines usually define language as ref lecting their professional perspectives. Language is a
complex multidimensional aspect of human be hav ior, and we need a clear definition of it before
we can discuss its acquisition, delay, and disorders.
First, language is symbolic. Words, whether spoken, written, or gestured, are symbols—
arbitrary repre sen ta tions of real ity. For example, a person’s name is arbitrarily chosen by his or
her parents. The letters and sounds of the name create a symbol that refers to the individual. The
word is the symbol, and that to which it refers is the referent. This symbol-referent relationship, or
semantics, is the core of language and the foundation of linguistic meaning. Whether the symbol
is tangible and concrete, such as comb, or intangible and abstract, such as truthfulness, words are
arbitrary symbolic repre sen ta tions of real ity.
Second, language is rule governed. There are rules for combining sounds into words and words
into sentences, or grammar. Specifically, phonology is the rule- governed way speech sounds are
sequenced and or ga nized in language. Syntax concerns sentence organ ization, especially word
order. All languages are rule governed and equally able to represent real ity; there are no substan-
dard human languages. Knowledge of the rules of language is competence, and the ability to use
them effectively is per for mance. All normal children are born with the ability to learn language,
and a hy po thet i cal part of the mind allowing this acquisition is called the language acquisition
device (LAD).
Third, humans have several ave nues of language expression and understanding. The five
primary modalities of language are speaking, gesturing, writing, reading, and understanding
the words of others. Typically, they are separated into expressive and receptive modalities. The
expressive ave nues of language are speaking, using expressive gestures, and writing. The recep-
tive modalities are auditory comprehension, understanding what has been gestured, and reading.
Performing and understanding simple mathe matics are also modes of language expression and
reception.
Fi nally, language is a social code that has been agreed on by a par tic u lar community. This
arbitrary rule- governed system is used by a community of like- minded individuals who accept
that system as their mode of communication. Language is a major part of the culture of the people
using it.
The following definition of language competence is relevant to communication sciences and
disorders and meets the previously mentioned requirements: Language is the multimodality abil-
ity to encode, decode, and manipulate symbols for the purposes of verbal thought and communi-
cation. Language per se may also be defined as a symbolic code that is rule governed, uses several
modalities and forms for expression, and serves as a communication code for social and societal