Bilingualism : Theoretical Perspectives of Language Diversity

Bilingualism and second language acquisition are discussed with reference to different theoretical perspectives. An integrated definition of bilingualism is provided and concepts underlying second language acquisition are presented. Theoretical perspectives according to Dodson (1985), Skinner (1985) and Krashen (1982) are explored. It is concluded that due to the diverse nature ofbilingualism, a single universal theory of second language acquisition does not seem feasible. The need for an increased awareness of the complexity ofbilingualism and second language acquisition, particularly within the multicultural and multilingual South African context, is highlighted.

Throughout history, humans have learned to use languages other than their native tongue to communicate with members of other language groups and other cultures.All humans can acquire additional languages, but must have the opportunity to use the language for real communicative purposes.
The literature on bilingualism is extensive and comes from many diverse disciplines.This results in many different, and often fragmented conceptualisations ofbilingualism.McCollum (1981) has pointed out that the early study ofbilingualism did not consider the bilingual's use of language within the speech community: neither the sociological factors that determine usage, nor the speaker's motivation for using one language over another in a particular social situation.The important relationship between language use and language structure was therefore mostly ignored.Recent literature does, however, focus on bilingualism in both linguistic and sociological terms.Miller (1984a), for example, views bilingualism as the complex consequence of the interaction of social and individual variables.The study of bilingualism should therefore include an understanding of the cognitive, linguistic and social development of the individual within the community context in which it occurs.This has important implications for the study of bilingualism within the multilingual and multicultural South African context.
The present climate of change in South Africa has an impact, not only on political find economic levels, but also on a cultural level.Part of this change process is an increasing acceptance and recognition of the diversity of populations and ethnic groups within our society.This seems to follow a global trend where there appears to be a significant increase in the awareness of cultural diversity within bilingual and multilingual communities (Miller, 1988).The fact that language is an inextricable part of the cultural life of a social group, and interdependent with the habits and values of behaving and sharing among members of a particular group, must be recognised.It can thus be said that a change in attitude toward different cultures, and greater tolerance between individuals of different cultures is likely to become more important in the years to come.Consequently, the importance of a sensitivity towards the linguistic and communication differences between cultures is implied.
It is contended that within the present South African context, a greater awareness ofbilingualism and second language development is needed amongst speech therapy and audiology professionals.Bilingualism and second language learning must, therefore, be understood within the context of both linguistic and communication differences between cultures.Terrel and Hale (1992) have stated that an understanding of learning styles is also relevant within such a context, as learning styles are mostly culturally determined.Speech therapists and audiologists must, therefore, gain insight into the normal processes of second language acquisition within particular cultural contexts.It is against this background that diagnostic and therapeutic implications regarding language acquisition and language delay must be considered.The purpose of the present paper therefore is to investigate the complexities of bilingualism and second language development.Different theoretical perspectives will be explored and facilitating factors in bilingualism and second language development will be presented.

A. BILINGUALISM DEFINED
The simultaneous acquisition of two or more languages in language learning environments associated with bi-and multilingual circumstances can be viewed as an exceptional and complex process.A single definition of the nature of bilingualism can, therefore, not adequately describe the nature of second language acquisition within a particular sociolinguistic context.The complexity of bilingualism lies in the function and purpose it has within a particular bilingual community.For too long there has been an incorrect conceptualisation of bilingualism, which focused on the rules and abstract aspects of the languages rather than on their use in conversation and communication (Miller, 1984a).This was also emphasised by Mackey (1962, in McCollum, 1981) when he asserted that bilingualism is not a phenomenon of language, but of the message.Such a definition of bilingualism clearly suggests the recognition of the relationship between language structure and language use, as well as the complex interaction between social and historical factors surrounding bilingualism within a particular community.Bilingual communities and individuals within these communities can not be described in terms of discrete or absolute characteristics.The language usage within a particular community is, furthermore, relative rather than absolute as it is determined not only by an individual's needs, motives, attributions and perceptions (Miller, 1984a), but also by a speech community's norms for language use in various domains (McCollum, 1981).The significance of such a conceptualisation of bilingualism is that it describes bilingual behaviour at the level of the individual as well as at the sociocultural level.It is thus clear that the language choice within a particular community is a product of the interaction between individual factors (age, sex, ethnic group and the individual's willingness to comply with the language laws of the community), the setting of communication (the physical and symbolic setting) and the topic of conversation (Miller, 1984a).
According to Dodson (1985), a discussion of bilingualism must also reflect the relationship between the two languages, and the language environment in which learning and communication take place.The relationship between languages is related to broad social circumstances rather than to any formal qualities of the languages involved.Within these social circumstances a language has a certain power within the community and a command of that language will be a prerequisite in gaining access to particular resources (Miller, 1984a).It must, however, be noted that the relationship between any two languages is not static and may change depending on the frequency and intensity of contacts in either language, and as a result of changes in the environment.Miller (1988, p.241) has described the relationship between the languages as "fluid and dynamic, varying from one aspect of the language system to another in accordance with a complex of socio-linguistic determiners".This implies that bilingualism cannot be understood in terms of two separate language entities without considering the effects of the one language upon the other.Utterances will therefore carry features of both languages.The sporadic alternation that occurs between the two languages is referred to as code-switching, while constant intermingling of the two languages is referred to as code-mixing.Both of these features are typical of all bilingual situations.Bilingualism can further be defined with reference to language proficiency and communicative competence.According to Williams and Snipper (1990), language proficiency refers to an individual's ability to process two languages in each of the following four skills: -the ability to understand a message in each of the spoken languages -the ability to respond in each language in a manner appropriate to the situation -the ability to read and understand a written message in each of the languages the ability to write in each language.Kessler (1984) has-defined bilingualism as a social process that develops along a continuum ranging from full proficiency in two languages to a minimal degree of competency in one of the languages.Bilingualism thus results from "efforts to communicate, to take part in that interpersonal interactive process defined by the social situation in which it occurs" (Kessler, 1984, p.27).This definition highlights the relevance of a communicative perspective in bilingualism.Acquiring a second language is, therefore, a complex process of developing communicative competence, and of using two language systems to communicate with individuals of differing languages and cultures.It is proposed therefore that a holistic perspective of bilingualism is needed to accommodate the complex yet dynamic nature of bilingualism.A holistic view will acknowledge the complementary and interdependent nature of the languages spoken.A holistic perspective of bilingualism will, furthermore, recognise the interaction between individual and sociolinguistic factors within a particular community.Bilingualism can be understood therefore within a communicative framework by focusing on both language structure and language use.

B. CONCEPTS UNDERLYING SECOND LANGUAGE ACQUISITION
Prior to a discussion of theoretical perspectives in second language acquisition and the development of bilingualism in children and adults, certain underlying concepts must be clarified, because these concepts are central to the acquisition of a second language.Bilingualism must, therefore, be understood with reference to the notions of communicative competence, language proficiency and language environment.According to Kessler (1984), this allows the various dimensions of bilingual language development to be placed into perspective.Figure 1 presents concepts relevant to second language acquisition.The various dimensions of communicative competence, as well as other factors that may influence communicative competence in second language acquisition are also indicated.

Communicative competence '
Canale and Swain (1980( , in Kessler, 1984) ) have stated that communicative competence is an essential part of communication, as it includes knowledge about the language as Jwell as skills in language use which underlie the actual communication.According to Miller (1988), communicative competence refers to the individual's ability to have basic language structures available, and the ability to use, maintain and structure these towards the desired conversation exchanges.It must be noted however, that the various dimensions of communicative competence are not acquired in a universal order.As Miller (1988) has indicated, an individual may have good grammatical competence (due to formal instruction), but poor sociolinguistic competence (inability to use linguistic knowledge), while another individual may have good strategic and sociolinguistic competencies but poor grammatical competence.It is, thus, implied that relative dominance in one competence (grammatical, sociolinguistic) will fluctuate over time in one indi-vidual and between individuals of the same speech community.Similarly, an individual need not be equally dominant in all competencies.It is thus clear that the various dimensions The South African Journal of Communication Disorders, Vol. of communicative competence together have an impact on second language acquisition.The dimensions identified by Kessler (1984) will be discussed separately.

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1.1 Grammatical competence.Thisisalsocalledlinguistic competence and refers to mastery of the linguistic code, that is, to mastery of the formal features of the language.The phonological, syntactic and lexical features of the language must be recognised and the ability to combine these features in pronunciation, word and sentence formation must be acquired.I 1.2 Sociolinguistic competence.Previously, the role of sociolinguistic competence in second language acquisition has received little recognition.This component refers to the sociocultural rules of language use, and defines the appropriate use of the language according to the social context in which communication occurs.Sociolinguistic competence is crucial in the interpretation of utterances for their social meaning.Kessler (1984, p.29) has stated that "this is an intricate developmental process for children 1 that takes place over time and reflects aspects of normal maturational processes".
1.3 Discourse competence.According to Kessler (1984) conversation is a form of interaction governed by rules for the introduction and maintenance of topics, opening and closing of utterances and turn-taking conventions.Discourse competence, therefore, refers to the ability to successfully communicate messages during conversation.The discourse component utilises grammatical components (the knowledge and use of language structures), sociolinguistic components (the constraints imposed by particular socio-cultural contexts), as well as the rules which govern ongoing conversation.
1.4 Strategic competence.This refers to strategies used to overcome breakdown in communication due to imperfect knowledge of rules in one or more dimension of communicative competence (Kessler, 1984).Two types of strategies can be identified.Firstly, communication strategies, which are devices implemented to communicate effectively, and second-ly, learning strategies, which are mental processes used to construct the rules of the language.Some strategies used in second language (L2) acquisition are similar to those used for first language (LI) acquisition.Corder (1981, in Kessler, 1984) has said that in the early stages of L2 development children may implement specific strategies but these may change as the child grows older and the degree of L2 proficiency increases.

Summary
The above discussion reflects the complexity of communicative competence.Moreover, the acquisition of communicative competence must be understood in terms of the interdependence of the above mentioned dimensions.Furthermore, the interaction between the two language systems in the acquisition of second language must be acknowledged (Kessler, 1984).The complex nature of this interaction is not yet fully understood.Communicative competence can however not merely be expressed as interaction between various components.The synergistic nature of the various interacting dimensions of communicative competence must at all times be recognised.A further crucial aspect, not to be overlooked, is the context in which second language acquisition takes place.

Language environment
A discussion of the language environment necessitates a distinction between language acquisition and language learning (Krashen, 1982).Language acquisition, according to Kessler (1984), is a natural, subconscious process that occurs in informal environments.The focus of this process, through which both first and second languages are acquired, is on communication or meaning.Language learning, on the other hand, is a conscious process, with a focus on grammatical competence (language form), that occurs in formal learning environments.This is a process available to older children and adults in developing a second language.According to Kessler (1984) language acquisition is central, and through language learning a system to edit language output is developed.The distinction between language acquisition and language learning must, however, be seen in a larger context.Skinner (1985a) has indicated that language is a function of learning, but that learning is also a function of language.Second language acquisition must, therefore, be viewed as a learning process.This has important implications for the language environment in which a second language is acquired.
A further factor related to language environment that has an impact on second language acquisition is the nature of language input.Optimal comprehensible input of language is an important characteristic of the language environment.This must, however, be seen with reference to individual factors in the language learning environment, for example, the levels of cognitive development and life experiences (Krashen, 1982).An individual factor that has a significant impact on second language acquisition is what Krashen (1982) has termed the affective filter.This refers to the relationship between the affective variables (motivation, self confidence and anxiety) and the process of second language acquisition.Kessler (1984, p.32) has concluded that "input is the primary causative variable in L2 acquisition and that affective variables either impede or facilitate delivery of input to the brain where language processing occurs".The degree to which the individual is open to input from the environment is dependent upon the amount of comprehensible input that is received and understood, as well as the strength of the individual's affective filter (how the environment is perceived affectively).
The acquisition and use of a second language within a particular language environment cannot be fully understood without reference to the mutual influence of the languages upon each other.We can, therefore, not assume that one language is dominant, either because it was acquired first or because it was the language of instruction.Such a view would neglect the impact of the different patterns and contexts of bilingual acquisition.Each language performs a particular communicative function and thus serves a different purpose in communication.The individual's competence in either language will be closely related to the nature and frequency of access to the situations in which the particular language is used (Miller, 1988).Bilingual language proficiency can thus not be understood in terms of separate language entities.Language proficiency as part of second language acquisition thus needs further clarification.

Language proficiency
A discussion of language proficiency must emphasise the connection between learning and language acquisition.According to Skinner (1985a), language proficiency relates directly to learning, and thus to the acquisition of knowledge.An integrated conceptualisation of language proficiency, language acquisition and learning is thus proposed.In this way, various language/learning issues and variables can be examined within a single framework.This has important implications for understanding the successful acquisition of a second language.The connection between language and learning can be explained by referring to the work of Piaget, Chomsky and Vygotsky on language acquisition.Chomsky and Piaget (in Skinner, 1985a), agree that interaction with the environment facilitates the acquisition of knowledge and language.There is, however, a difference in emphasis, as Piaget has suggested that learning and language develop from successive experiences with the environment, whereas Chomsky has indicated that interaction with the environment activates what the learner brings to the interaction.The essential nature of language and thought as prerequisites to communication thus become an important issue to consider.Vygotsky (1962, in Skinner, 1985a) has stated that the union of thought and word produces meaning: meaning is thus a continual interaction between these two components.According to Vygotsky, the acquisition of grammar and vocabulary is the beginning in the development of meaning, while changes in meanings and the acquisition of new meanings represent learning.It can thus be concluded that knowledge is a function of language and that the acquisition of knowledge, although related to language, will be limited by the language proficiency of the learner (Skinner 1985a).
Language proficiency is, therefore, an integral part of the learning process.This means that an individual's academic performance may be directly related to language proficiency.Cummins (1981( , in Skinner, 1985a) ) became interested in the academic difficulties experienced by apparently fluent second language speakers.Based on the notion that different languages have different functions in different contexts, Cummins has identified two kinds of language proficiency: basic communication proficiency and cognitive academic proficiency.Basic communication skills entail the use of surface features of the language, and thus basic knowledge and understanding of language structures.Academic proficiency, however, includes higher language abilities.This refers to the ability to "think" by using the language, thus manipulating meanings inherent to the language itself.According to Skinner (1985a), this conceptualisation can best be explained with reference to Bloom's Taxonomy of Cognitive Learning (Table 1).From Table 1 it can be seen that academic proficiency in a language can not be separated from critical thinking skills.Skinner (1985a) has thus concluded that language can be related directly to learning.Cummins (1981( , in Skinner, 1985a) ) has suggested that language proficiency be seen as a developmental progression rather than in terms of distinct and separate realms.He thus portrayed language proficiency in terms of two vectors: -the ability to identify and communicate meaning in the absence of contextual clues, and -the ability to think (determine/communicate meaning) in cognitively demanding situations.Table 2 presents the dynamic developmental progression in language proficiency (from quadrant A to quadrant D) as indicated by Cummins.Quadrant A refers to basic communication proficiency (context-embedded and cognitively undemanding communication), whereas quadrant D refers to cognitive academic proficiency (context-reduced and cognitively demanding communication).A language learner there- The South African Journal of Communication Disorders, Vol.

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Bili uai: Theretical Perspective of Language Diversity fore progresses from A to D as more meanings become available.This view clearly supports the connection between language and learning.Cummins' conceptualisation of language proficiency (1981, in Skinner, 1985a) can further be understood with reference to Vygotsky's notions on childhood grammar and adult grammar, represented by basic communication skill and cognitive academic language proficiency respectively.The development of language proficiency along a continuum once again becomes apparent.Basic communication skill thus refers to the initial command of grammar whereby the child has a broad use of the phonics and syntax of the language.The child is able to converse fluently at seemingly adult level, but lacks abstract, deliberate thinking skills.As the child progresses in concept development, word meanings change which represents development in language proficiency (toward cognitive academic proficiency).A child and an adult may use exactly the same words, although the meanings may be very different for each.Meanings of words change as the thoughts embodied in those words change.Adult grammar is thus nearer to cognitive academic proficiency as it involves the ability to deal with meanings and relationships at an abstract level (Skinner, 1985a).

Summary
The preceding discussion highlights the various dimensions underlying second language acquisition as well as factors that may contribute to second language acquisition.This has important implications for the understanding of bilingual development within a particular context.Furthermore, the relevance of analyzing an individual's language system as a whole becomes clear.Manyj of the issues regarding language learning addressed by different theories are dependent upon which competencies are examined and under which circumstances.This leads to different views on which factors will facilitate bilingualism.The complexity of second language acquisition thus becomes apparent which clearly prompts a more holistic perspective on second language acquisition.

C. SECOND LANGUAGE ACQUISITION: A THEORE-
TICAL PERSPECTIVE Kessler (1984) has stated that to become bilingual is a uniquely human phenomenon, yet an extraordinarily complex process.Many different theoretical perspectives have therefore been proposed to explain the acquisition of a second language.It must also be stressed that "theory" and "theoretical research" have for too long been the only input in decisions on methodologies and materials for second language teaching.For this reason Krashen (1982) has proposed interaction between the various approaches that influence language teaching methodology.
Theories of second language acquisition and bilingual development are concerned with the same basic issues as theories of first language acquisition, i.e. rate, pattern and processes of language development (Genessee, 1988).An additional interest in second language acquisition, however, in contrast to first language acquisition theories, is whether the patterns and processes of language learning are influenced in some way by learning two or more languages simultaneously; or by learning a second language after a first language has been acquired.We can therefore ask whether there are interactions between the two language systems that result in a pattern of language acquisition that is different in comparison with monolingual development.This is further complicated by the possibility that different processes might be involved in successive acquisition of more than one language than those involved in simultaneous acquisition of two languages.A number of different theoretical approaches are evident in the literature, all with differing views regarding the relationship between LI and L2.There is, furthermore, no consensus regarding the process and sequence of L2 acquisition, or whether or not a second language is acquired in the same way as the first language.
Early theories, for example grammar-based approaches, focused on codifying the second language into rules of morphology and syntax to be explained and memorised.Oral work was consequently reduced to a minimum.The real experience of the language in natural communication situations was largely ignored (Krashen & Terrell, 1983).Current theories are, however, more tuned to the communicative importance of second language learning.This means that to acquire communicative competence, the key component is the use of language for real communication and that exercises and drills are not necessary.Krashen (1982) has pointed out that communicative ability develops rapidly, and that grammatical accuracy increases at a slower rate and after much experience with the language.The following discussion on current theories will reflect three different perspectives on second language acquisition.Dodson (1985) has emphasised that bilinguals, irrespective of age and environment, have a preferred (LI) and a second language (L2).The terms "preferred" and "second" language must, according to Dodson (1985), always refer to the languages of individuals as the term "dominant language" refers to the language of groups.A distinction can thus be made between an individual's mother tongue (or first language of acquisition) and his/her preferred language.The mother tongue for many people, is not their preferred language.Dodson's (1985) theory explains increasing language competence in terms of medium-orientated communication and messageorientated communication.According to Dodson (1985), the process whereby the language learner focuses on language or the language learning process, can be called medium-orientated communication.Other utterances, in which the message is more important than the medium, have been classified as message-orientated communication.These two forms of communication which can be seen as extremes of a spectrum within which all utterances can occur, are presented in Figure 2. A and Β (in Figure 2) represent all possible utterances that can be made.These two levels of activity are not restricted to speaking and listening and can also be applied to the development of reading and writing.Most utterances are predominantly A or Β although a mixture of A and Β can occur depending on the speech intentions of the speaker.Dodson (1985) has suggested that the acquisition of a second language initially Increasing Second Language Proficiency - depends largely on medium-orientated communication.As language proficiency increases, the amount of necessary medium-orientated communication decreases.A developmental trend is thus implied.Medium-orientated communication is consciously focused on the "mechanics" of communication, while at the message level, communication is more spontaneous, not consciously dealing with the grammatical correctness of a message.At the medium level, the aim is to communicate to the self something about language and the languagelearning activity.The direction of such communication is thus inward.Dodson (1985, p.36) has stated that communication at this level is important as it "helps developing bilinguals to separate their two languages, to reduce or eliminate cross language interference and to develop their facility to codeswitch effectively".At the message level the direction of communication is outward.Medium-orientated communication thus refers to the sharing of messages with others on different occasions.Language acquisition can, therefore, be described as a fluctuating process between language learning and application of what has been learnt.The fluctuation takes place between bilingual preferred/second language medium-orientated communication and monolingual second language messageorientated communication (see Figure 2).As second language proficiency increases, the individual relies less on prior medium-orientated confirmation of any message-orientated utterance.It is thus proposed that second language acquisition can be encouraged by allowing the developing bilingual to experience the fluctuation and interdependence of monolingual and bilingual activities in "varying proportions according to the area of experience and the degree of proficiency" (Dodson, 1985, p.339).

Dodson (1985)
A positive feature of this theory is that Dodson (1985) has emphasised the environment in which communication occurs.* He has indicated that unfavourable linguistic treatment may have a handicapping effect on second language acquisition, thus causing a large number of second language utterances not to be made fully at message-orientated level.This aspect may be related to Krashen's (1982) proposal of an affective filter.This means that the individual perceives an unfavourable language environment which then has a negative impact on the acquisition of the second language.It is clear that this theory has valuable features that can be implemented in the explanation of sequential acquisition of a second language.
Fluctuation between these two levels of communication as part of second language acquisition, is an important aspect of this theory.It is, however, possible that the distinction between the preferred and second language status as explained by Dodson (1985), is overemphasised.

Skinner (1985)
According to Skinner (1985a, p. 106) the ideas of Piaget, Chomsky, Vygotsky and Cummins can be merged into "a unified conceptual construct" as a means of directly correlating primary language acquisition, language proficiency and learning.Furthermore, this composite construct can be successfully applied to the explanation of second language acquisition.Figure 3 demonstrates how Skinner (1985a) has proposed that the ideas of Piaget, Chomsky and Vygotsky be merged.Skinner (1985a) has noted that the word/age axis (representing grammar and vocabulary) indicates growth in knowledge and language facility.The presentation of growth against "thoughts" and "meanings" indicates Vygotsky's proposals on the unity of "word" and "thought" in order to produce "meaning"'.This can further be interpreted by adding Cummins' ideas on language proficiency to Vygotsky's notions of thought and word unity.It thus becomes clear that as meanings become available, freedom from contextual cues increases.This provides the opportunity to use language for cognitively more demanding purposes.This unified theory represents Skinner's (1985a) idea of a single construct that unifies language proficiency, language acquisition and learning.The dynamic growth in language acquisition, and its link to the learning process, can be seen in relation to knowledge.
The value of this integrated approach to language acquisition is that it can be applied successfully to the acquisition of a second language.Not only is this model based on sound theoretical principles, but it has clear methodological guidelines for the language learning process.As indicated by Skinner (1985b) in this model, the language learner is assisted by connecting thoughts with words.It is thus implied that LI will be the language of instruction for L2 acquisition, particularly in The South African Journal of Communication Disorders, Vol.(Skinner, 1985a and1985b) the early stages.This may also be related to Dodson's (1985) view of the fluctuation between medium-(bilingual activity: L2) and message-(monolingual activity: LI) orientated communication.The use of contextual clues as a means of conveying meaning thus contributes significantly to the acquisition of meaning in the early stages of L2 learning.Furthermore, the value of this approach lies in the fact that it considers cognitive competency as a key factor in determining the level of language proficiency and the ability to think in the language.As stated by Skinner (1985b, p.385), "a programme that attends to the transfer of concepts from LI to L2 should result in more rapid development of language proficiency".Through this model, concept development can thus be maintained at age-appropriate levels.This means that an effective methodology will ensure instructional content and sequence of explanation on the level of LI conceptual development (Skinner, 1985b).The particular significance of this model is, however, that it pays careful attention to what Skinner (1985b, p.386) calls "the language equivalency assumption", i.e. that L2 is acquired in the same way as LI.There is thus an awareness of the methodological problems involved vyhen a language learner is forced to function at a conceptual level below his actual equilibrium in LI (see Figure 3).This results in a cognitive gap, as the learner is unable to unify adult (more advanced) thoughts with L2 words.Skinner (1985b, p.5) has argued that "the gap can also be expressed as a language proficiency gap, because of the connections between language proficiency and learning".He has proposed that the cognitive gap and language proficiency gap are related to the learner's anxiety and frustrations in acquiring the second language.Such affective learning difficulties are therefore the result of a disorientation imposed by the methodology of language teaching (Skinner, 1985b).This has important implications particularly for adults in the process of acquiring a second language.It must, however, be pointed out that this model places almost exclusive emphasis on language proficiency.As discussed previously, this is only one of the significant issues underlying second language acquisition.It is suggested that the use of language (i.e.communicative competence) should be acknowledged more explicitly.In addition, more emphasis is needed ori issues related to factors in the language environment conducive to successful acquisition of a second language.

Krashen (1982)
According to Krashen (1982) the best methods for second language teaching are those that supply comprehensible input in low anxiety situations, containing messages that students really want to hear.It is suggested by Krashen and Terrell (1983) that language acquisition occurs mainly through comprehensible input, viz.by understandable auditory and written input.They have described the following four principles in their theory of second language acquisition: -comprehension precedes production, thus emphasising that acquisition is the basis for production ability and that for acquisition to take place, the message must be understood -production takes place in stages, meaning that an individual is not forced to speak unless he/she is ready to do so -the syllabus should consist of communicative goals where the focus of language activities is organised by topic not by grammatical structure -all language acquisition activities must foster a lowering of the affective filter of the acquirer.Based on these principles, five hypotheses have been formulated as part of this second language acquisition theory.These hypotheses are not absolute, but subject to change.
3.1 The acquisition-learning hypothesis.According to this hypothesis, there are two distinct ways in which an adult can acquire a second language.Firstly through language acquisition, which means that language is used for communicative purposes, and secondly through language learning, thus implying conscious knowledge about the language.This is an important distinction because it determines the nature of language input from the language environment.It is thus implied that language teaching is too often aimed at learning, and not acquisition of the second language.
3.2 The natural order hypothesis.According to this hypothesis, grammatical structures are acquired (not necessarily learned) in a predictable order: certain structures are acquired early and others late, allowing for the possibility Die Suid-Afrikaase that structures may be acquired in groups.Regarding second language acquisition in adults, Krashen and Terrell (1983) have indicated that a natural order for the acquisition of morphemes exists.This is shown in Figure 4.The fact that the natural order for adults acquiring a second language appears under certain conditions, forms the basis of the following hypothesis.

3.3
The monitor hypothesis.This hypothesis emphasises the limited function of conscious learning as a language monitor (editor) in adult second language performance.Fluency in production is thus the result of what is acquired in natural communication situations, whereas formal language knowledge has the function of checking and correcting the output of the acquired system.The monitor hypothesis claims that conscious learning has value as a "language monitor" only and that it is not used to initiate production in a second language (Krashen, 1982).

The input hypothesis.
Input has become a central issue in many theories of second language acquisition.Krashen (1982) has emphasised the importance of input over other aspects of second language learning in his argument that output, or opportunities to use the language productively, are not necessary to develop production skills.In the hypothesis, therefore, it is claimed that language acquisition occurs through the understanding of messages, that is, through receiving comprehensible input.Efficient input is described as a message that involves general language difficulty not exceeding the learner's ability (Dornyei, 1991).Krashen and Terrell (1983) have argued that when input is enough, the equation of i + 1 will be satisfied, where stage i refers to the acquirer's level of competence and 1 refers to the stage immediately following i along some natural order.This has important implications for the language material the learner is exposed to as part of the acquisition process.The practical significance of this hypothesis is, however, questioned by Dornyei (1991) as he has contended that it does not serve as a satisfactory guide for language teachers.Furthermore, Genessee (1988) has argued that more attention should be given to the role of output.Swain (1985, in Dornyei, 1991) has argued that comprehensible input is not the most important ingredient in language teaching.An output hypothesis was thus proposed by Swain (1985, in Dornyei, 1991) to fulfil functions in communication not met by the input hypothesis.Efficient output thus involves more than uncontrolled learner talk.The language learner should, according to the output hypothesis, be prompted to express messages more appropriately and more precisely.It thus appears that fluctuation between these hypotheses may result in optimal language learning conditions.
3.5 The affective filter hypothesis.According to this hypothesis that attitudinal and affective variables relate to second language achievement, language learners with optimal attitudes have a lower affective filter, meaning that they are more open to input.According to Krashen and Terrell (1983) the right attitude will encourage the learner to obtain more input and to interact with speakers of the target language, while at the same time, being receptive to the input they receive.A review of the literature indicates that this hypothesis has the most important impact on second language acquisition theory as many other theories have been altered to accommodate the role of affective variables.It has implications not only for the language environment, which should present favourable language conditions to foster positive attitudes, but also for the individual language learner, to be aware of environmental factors and his/her own response to these.Although Krashen's (1982) theory of language learning has been the source of much controversy and academic discussion, it can be viewed as a comprehensive theory of second language acquisition, mostly applicable to older language learners.Dornyei (1991, p.33) has pointed out that "this theory has undoubtedly succeeded in bridging the gap between linguistic theory and actual language teaching".An advantage of this theory is that it focuses on the acquisition of communicative competence in natural communication settings.In addition, the emphasis in this theory on affective and attitudinal variables makes a valuable contribution to the theoretical perspectives on second language acquisition.
From the above discussion on three theoretical approaches, it can be seen that in spite of some overlap in concepts, each theory's main focus is on a different aspect of second language acquisition.The theories discussed are aimed at accommodating the complexity of bilingualism, as well as the various factors that influence second language acquisition.As pointed out by Genessee (1988), individual differences im second language acquisition are important issues to consider.Factors associated with age, cognitive style, personality, type and amount of exposure, attitudes and motivation have an impact on language learning and language acquisition.The social, cognitive and linguistic consequences of being bilingual must also be considered in a theoretical approach to bilingualism.Due to the diverse nature of bilingualism, an integrated perspective on second language acquisition is proposed.This implies a holistic view of the development of bilingualism, based on the interdependence of communicative competence, language proficiency and factors in the language environment!Furthermore, such an approach to bilingualism can be based on a composite of the strengths of the various theoretical perspectives, leading to an integrative theoretical view which can be applied to each unique bilingual situation according to the needs of language learners and the features of the language environment.

D. SECOND LANGUAGE ACQUISITION
In the discussion on second language acquisition which relates to both children and adults an attempt will be made to highlight those factors that will facilitate language acquisition The South African Journal of Communication Disorders, Vol.

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Bili»i uaUein: 'Theoretical Perspectives of Language Diversity • children.Kessler (1984) has indicated that for an understanding of bilingualism in children one must consider the developmental perspectives of communicative competence for very young children, older pre-school children and schoolaged children.Furthermore, the relationships between the bilingual child's two languages, as well as aspects of communicative competence related to school contexts, must all be taken into account.The following two points are important to consider when discussing second language acquisition.
Simultaneous versus sequential acquisition.Kessler (1984) has pointed out that bilingualism in children is related to the timing of acquisition of the two languages.The process of acquiring two languages simultaneously is referred to by Swain (1972, in Kessler, 1984) as first language bilingualism.According to Schiff-Myers (1992) this can also be called infant bilingualism.The child develops both languages simultaneously in naturalistic situations.Ben-Zeev (1984) has stated that bilingualism can also develop in a situation where the child experiences language-switching in the environment from a very young age, as in the case of a caretaker switching from one language to the other whilst talking to the child.This type of developmental bilingualism begins at the onset of language in infancy and refers to the acquisition of two languages prior to age three.The acquisition of another language after this point is referred to as sequential or successive bilingualism.This occurs when one language follows or is second to the first in acquisition order.Schiff-Myers (1992) has referred to this as childhood bilingualism.The child hears only one language in the home and is only later exposed to a second language.Second language acquisition in children must, however, be separated into L2 acquisition in the pre-school years and L2 acquisition in the school years.This is an important distinction as the older child is at a higher maturational level and, during the school years literacy, reading and writing tasks become an integral part of the total process of becoming bilingual.Schiff-Myers (1992, p.29) has referred to these children as "sequential or consecutive language learners with the first language designated as LI and the second language as L2".
Psycholinguistic similarities and differences between LI and L2 acquisition.Authors seem to differ regarding the linguistic faculties or linguistic principles involved in first (LI) and second language acquisition (L2).Schachter (1986( , in Genessee, 1988) ) has identified certain basic differences in first and second language acquisition.Schachter has cited evidence that older second language learners, in contrast to first language learners, often fail to acquire basic linguistic structures or acquire incorrect or incomplete language forms, thus they do not always acquire complete competence in the target language.The first language, furthermore, has a considerable influence on the acquisition of the second language.This may be due to the nature of the learning environments in which a second language is acquired.According to Schachter (1986( , in Genessee, 1988), these differences do not occur with acquisition of two languages simultaneously during the period of primary language development.The role of cognitive factors in LI and L2 acquisition must also be acknowledged.According to Genessee (1988) cognitive factors of a non-linguistic nature (i.e.memory capacity and perceptual-motor abilities) influence the child's ability to perceive and to produce particular linguistic structures in first language acquisition."The determining factors in primary language development are largely cognitive or conceptual in nature because the language acquisition device is a given, while the determining factors in subsequent language learning are largely linguistic in nature since cognitive/perceptual | maturity is a given" (Genessee, 1988, p.67).A further factor to consider in LI and L2 acquisi-tion is the relationship between the two languages.Research has shown that the conditions under which, and the extent to which, a second language learner uses the first language when processing the second language are important factors to consider.Genessee (1988) has stated that the older language learner's knowledge base includes specific contextual knowledge regarding social relations within a particular social group.Such established conversation knowledge may, therefore, have an effect on the acquisition of a second language.In contrast to the older second language learner, the pre-schooler acquires language in parallel with social knowledge and thus the influence of established social knowledge on language acquisition is not profound.
The conclusion that can be drawn from these theoretical arguments is that bilingual development is psycholinguistically distinct from monolingual or first language acquisition.Genessee (1988) has summarised such research by stating that children acquiring two languages simultaneously initially go through a stage of extensive linguistic interaction when the two language systems are mixed.This can easily be seen as a stage of linguistic confusion or as a unitary, undifferentiated language system.These points will be discussed further in the following section.

Simultaneous acquisition of languages in young children
Two patterns of simultaneous acquisition can be identified.Firstly, where the child is presented with different languages in a one-person, one-language association and secondly, where the languages are not person specific and are alternated in the same discourse situation.Extensive code-switching may thus, for some children, be the primary type of input rather than one which clearly distinguishes two language systems (Kessler, 1984).Evidence of uneven development during the simultaneous acquisition of languages must be acknowledged.Children often develop faster in the language to which they are most often exposed.The quantity of language input within a particular language environment may, therefore, provide balanced exposure to both languages or greater quantity for one of the languages.These factors interact in complex ways and can, according to Kessler (1984), affect the degree of bilingualism, the rate of realisation of two distinct language systems and the degree of negative language transfer (LI and L2 interference) between the two languages.According to Kessler (1984), such interference, or code-mixing seems to occur when the adult input is characterised by extensive codeswitching.Code-mixing refers to "a sophisticated, rule governed communicative device used by linguistically competent bilinguals to achieve a variety of communicative goals" (Genessee, 1988, p.69).Mixing the linguistic elements from one language into another is constrained so that the syntactic rules of both languages are respected.Switching between languages occurs as a function of certain sociolinguistic factors, such as the setting, and tone and purpose of the communication situation.Fatini (1976, in Kessler, 1984, p.36) has stated that "the more separate the environments in which each language is used and the more consistent the language use within each of these environments, the more rapidly and the more easily bilingual children learn to differentiate their linguistic systems".It can thus be seen that the nature of linguistic input is an important aspect of the language environment as a facilitating factor ofbilingualism in young children.Kessler (1984) has highlighted two stages in simultaneous language acquisition.
1.1 Undifferentiated single-language system.Input taken from both languages is acted upon by cognitive processes Die Suid-Afrikaase to form a unique language system consisting of elements of both languages.The two languages are, therefore, not encoded separately but as a common core of rules.Code-mixing is a typical and natural feature of simultaneous acquisition.There are at least two sources of code-mixing at this level.Firstly, the language input may be a mixed code.Secondly, during the simultaneous acquisition of two languages, a period of insufficient metalinguistic skill prevents the child from separating the two languages.As a consequence, a mixed language develops along similar lines to a single language.A functional and acquisitional differentiation emerges around the age of two years and six months (Miller, 1988).It is then, that codeswitching as opposed to habitual code-mixing gradually becomes predominant.Another phenomenon evident in sequential acquisition is a silent period during which the child has limited L2 expressive language, despite good comprehension of the language.This may be a period of consolidating knowledge of L2 to enable the child to use L2 without having to resort to LI. Pressure on children to communicate during this phase forces them to use LI-based strategies to succeed (Miller, 1988).
1.2 Differentiated language systems.As bilingual children develop they gradually begin to differentiate between the two language systems.According to Kessler (1984) the precise age at which this may occur varies as input conditions, language balance and other linguistic and sociolinguistic variables interact.Differentiation occurs when the child starts to communicate with different people in different languages.Code-switching becomes evident depending on the conditions of the communication situation.Bilingual children learn to identify a specific language with a particular person and with particular situations.
In order to create conditions favourable to second language acquisition, Kessler (1984) has stressed the importance of understanding the complex and fragile nature of bilingualism.Should a child be removed from bilingual language input, one language may soon be lost to the child.Continued input!however, can stabilise bilingualism, allowing for distinct and separate language use.Kessler (1984) has emphasised that for bilingualism to be maintained, the continued use of both languages in communicative, naturalistic settings is required.

Sequential acquisition of languages
This implies that the acquisition of LI has taken place before L2 acquisition.It therefore tends to be related to older children and adults.
2.1 Sequential acquisition in pre-school children.By the age of three years, children usually have basic communicative competence in their first language.Acquisition of a second language at this age thus implies adding a second language to one already in place.In informal settings, pre-school children will direct their attention to the meaning of utterances rather than to linguistic forms.According to Krashen (1982) this is an important process used by children for developing a second language.Kessler (1984, p.43) has indicated that this process can be greatly impaired "when input is deficient in quality or quantity or when children, because of the complex set of personality characteristics each brings to the task, have negative attitudes or do not have access to the cognitive and social strategies that facilitate language acquisition".This has important implications for the facilitation of a second language at pre-school level.It is recommended that the language environment must be natural, with emphasis on communication.Krashen's (1982) emphasis on affective and attitudinal variables in relation to language achievement, provides valuable guidelines in this regard.The aim is therefore, to foster a positive attitude toward L2 in a favourable language environment.
Corder (1981( , in Kessler, 1984) ) has referred to L2 acquisition at the pre-school level as acquisition of an inter-language.This is a unique language system constructed by the child and can be described as "a dynamic, fluid system shifting and changing as the child reorganises it to accommodate new rules" (Kessler, 1984, p.43).The inter-language can be seen as a developmental continuum characterised by so-called errors which mark divergence from the native-speaker norms for the target language (language acquired).Making of errors thus plays a vital and necessary role for the successful outcome of L2 processes, as they provide evidence of the learner's acquisition strategies.It is possible that Dodson's (1985) view on fluctuation between bilingual medium-orientated communication and monolingual message-orientated communication (see Figure 2) is applicable in this regard.This would mean that during the early stages of sequential bilingualism, the child relies heavily on the LI system, as it is drawn upon for L2 development.As language proficiency increases, LI has less influence and the errors observed in the inter-language increasingly resemble the normal, developmental errors which are part of the child's acquisition of the LI.Interaction between LI and L2 does, however, continue, and it must be acknowledged that L2 acquisition is not a linear process.

Sequential acquisition in older school-aged children.
Increased age, cognitive maturity and extensive language experience are variables which can enhance the language acquisition in older children.According to Kessler (1984), other variables such as increased awareness of the separateness of the two language systems, differences in the language environment, differences in language input, as well as awareness of the affective environment in combination with the more highly developed affective filters also influence language acquisition at this level.Here, literacy, learning and writing become crucial aspects of L2 acquisition.Cummins' conceptualisation of communication proficiency (1981( , in Skinner, 1985a) ) has relevance for understanding language acquisition in older children (see Table 2).The developmental nature of language acquisition from context-embedded basic interpersonal communication to cognitively demanding tasks in context-reduced settings must be acknowledged.According to Cummins (1981, in Kessler, 1984), cognitively-academic language is crosslingual and thus applicable to any language context, LI or L2.This means that language proficiency on this level, although mastered in LI, will carry-over to L2, when sufficient L2 code is available.Learning a second language for school use is a task that imposes its own specific demands.The child must become aware of language as a separate structure and learn how to use it in context-reduced forms.This has important implications for L2 reading and writing ability as the child must write or understand a message correctly without recourse to contexts available through face-to-face encounters of spoken language.Kessler (1984) has emphasised that differentiation between context-embedded and context-reduced and cognitively demanding and cognitively undemanding tasks outlines a critical distinction between L2 development in the pre-school years and L2 development at school.

Sequential acquisition in adults.
Second language acquisition in adults can be understood with reference to sequential bilingualism.Krashen's (1982) approach to second language acquisition is most suitable for the adult language learner.Adults often appear to be more efficient language learners, possibly due to greater cognitive maturity and better metalinguistic skills.Affective variables are also crucial in The South African Journal of Communication Disorders, Vol.
Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2012) language acquisition at this level.The language learner must have a positive attitude toward the language and feel confident within the language environment.Biological factors, cognitive factors and social factors thus interact in providing optimal conditions for adult language learning.Code-mixing and codeswitching have also been observed in adult second language learners.

Summary
The above discussion of second language development indicates that complex interactions of various factors related to the individual language learner, the language environment and the nature of language input determine optimal conditions for language learning.It is proposed that these conditions must be understood within a particular theoretical framework, suitable to unique conditions of a particular bilingual situation.All these factors emphasise that second language acquisition is not a predictable, even process.The process is, according to Miller (1988), open to influences from external (environmental, nature of language input, role of first language) and internal (affective, personality, cognitive-linguistic maturity at onset of acquisition) factors.

CONCLUSION
The aim of this paper was to describe bilingualism and second language development in children and adults.Different theoretical perspectives were explored and facilitating factors in the acquisition of a second language were discussed.The discussion highlighted the complexity ofbilingualism and emphasised that an understanding of second language acquisition should focus on the relation between language structures and language use within a particular bilingual community.Communicative competence, language proficiency and aspects related to the language environment were emphasised as important underlying concepts to second language acquisition.A holistic approach to bilingualism was proposed.
It is clear that speech therapy and audiology professionals in South Africa must become(more aware of the implications of working in multilingual and multicultural settings.A great deal of diversity is presentjin the languages used in South Africa.Bebout and Arthur (1992, p.45) have emphasised that "professionals need to become cross-cultural communicators in order to provide adequate services when working with a culturally and linguistically diverse population".This has important implications for the evaluation of a child's language abilities.Professionals working within multicultural, multilingual contexts must therefore become knowledgeable concerning the interaction of LI and'L2 within bilingual communities.Furthermore, the cultural factors relevant to any specific bilingual situation, for example English/Afrikaans as opposed to English/Zulu, must be recognised.Greater understanding of the complexity ofbilingualism within a particular cultural context, and knowledge of the theoretical issues involved in second language acquisition will enable speech therapy and audiology professionals to meet the needs of each unique bilingual situation within the South African context.As indicated by Miller (1984a, p. 7), favourable contexts for the acquisition and use of languages will be societies where "pluralism is tolerated, preserved or even encouraged".

Figure 1 :
Figure 1: A schematic presentation of the concepts underlying second language acquisition and factors that affect the development of a second language (adapted from Kessler, 1984).
Figure3: A unified model for Language acquisition, language proficiency and learning(Skinner, 1985a and 1985b)

Figure 4 :
Figure 4: Average order of acquisition of grammatical morphemes for English as a second language: children and adults (from Krashen & Terrell, 1983, p. 29).