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<Paper uid="W97-1007">
  <Title>From Psycholinguistic Modelling of Interlanguage in Second Language Acquisition to a Computational Model</Title>
  <Section position="4" start_page="0" end_page="0" type="intro">
    <SectionTitle>
2 A Conceptual Model for
Interlanguage Level Models
</SectionTitle>
    <Paragraph position="0"> In this section we show the psycholinguistic model for Interlanguage Level Models (ILMs). The ILMs characterise different grammars of the interlanguage the ideal learner can have for the second language at each language level. It must be noted that, although some linguistic structures are particular to each student, others are common to all students at the same level. These common structures are those which will be represented in the ILMs.</Paragraph>
    <Paragraph position="1"> We represent ILMs by means of two different types of sequences of models: consecutive sequences and embodied sequences. For each level, two different kinds of knowledge are represented: the variable knowledge, the knowledge the student is supposed to be learning; and, the fixed knowledge, the knowledge the learner has already acquired. The knowledge the language learners have acquired at a concrete level includes the knowledge acquired at previous levels.</Paragraph>
    <Paragraph position="2"> However, the knowledge they are learning at each level follows a different structure: each model from each level is independent from other levels, although intersections between knowledge at different levels tan occur at times. The set of different variable language structures at each language level consists of consecutive sequences of models, while the set of fixed ones consists of embodied sequences (see Fig.</Paragraph>
    <Paragraph position="3"> 1). When we say fixed knowledge or variable knowledge we refer to the language structures the learners have in their interlanguage, without making any distinction between the representation of correct and &amp;quot;incorrect&amp;quot; structures. When we specify interlanguage all the language structures, right and &amp;quot;deviant&amp;quot;, are represented in the same way. It must be noted that while a language structure used by high level learners can be considered deviant, the same structure in the case of beginners could be seen as correct at their level. For example a deviation at 10th level like avoiding the word ote 'could' (i.e. nor da? 'who is?' instead of nor ore da? 'who could be?' ) is not considered a deviation in lower levels of the language.</Paragraph>
    <Paragraph position="4"> Language structures of the interlanguage are context-dependent (Selinker, 1992). Language learners create discourse domains as contexts for interlanguage development.</Paragraph>
    <Paragraph position="6"> Fig 1. ~tw~ctioa d ~l l.n te fla ngmlge ~dd ef X from X* L Such domains are constructed in connection with life experiences that have importance for the learner, containing prototypical interlanguage forms associated with the content area by the learner. Interlanguage may be developing in one domain while at the same time it may be stabilised, or possibly fossilised, in another (Selinker, 1992). So, language structures of the interlanguage include information about context where they appear. Some structures appear in the interlanguage in specific contexts, however, others appear in any context. That is why we can see, in the representation below that structures can be context-dependent or context-independent. A first approximation of the representation (using DDL) for the ILMs is as follows: structure Interlanguage_Level_Models; parts: models: set (inst ance(Interlanguage._Level_Model)); structure Interlanguage_LeveLModel; parts: fixed_knowledge: set (instance(interlanguage_xnodel)); cardinality: rain 0 max HIGHEST_LEVEL; variable_knowledge: set (instance(interlanguage_model)); cardinality: rain 0 max HIGHEST._LEVEL; Martxalar, Diaz de Ilarraza ~J Maite Oronoz 51 Computational Model of Interlanguage structure interlanguage_model; parts:</Paragraph>
    <Paragraph position="8"> properties: language_level: integer-range(I, HIGHEST.LEVEL); structure interlanguage_structure_context_indep ; subtype-of: interlanguage_structure, structure interlanguage_structure_context_dep; subtype-of: interlanguage_structure, structure interlanguage_structure; subtypes: interlanguage_strueture_context _indep, interlanguage_structure_context _dep; parts: phenomena: set (instance (linguistic_phenomenon)); conditions: set (instance (interlanguage_condition)); properties: description: string; eontextualization: boolean; deviation: boolean; stabilization: function(stabilization of the rules associated to each phenomenon); axioms: If contextualization= False then conditions=&lt;&gt;.</Paragraph>
    <Paragraph position="9"> The same interlanguage structure can be deviation=True at the X language level and deviation=False at the Y language level. The value of stabilization is {rarely, sometimes, usually, always} The interlanguage structures we propose are composed of linguistic phenomena which occur under some conditions. The properties of the interlanguage structures are: description of the structure; contextualization, that is, context dependent or context independent; deviation, which marks if the structure must be considered deviant at the related language level and, finally, stabilization.</Paragraph>
    <Paragraph position="10"> The stabilization property is a qualitative value  which represents the acquisition level of the structure for a particular language level. It is by means of this property that a language structure inside the student's interlanguage is considered fixed knowledge or variable knowledge. When the value of the stabilization property is always it means that the language structure has been assimilated by the learner and in the future it would be quite difficult making some changes. However, when the value is rarely, there is a high variability of the language structure, and, therefore, a good teacher (could be an ICALL system) should be able to help the learner to take away those structures in case they would not direct the student towards a target language. In the first approximation of the representation for the ILMs we have represented interlanguage structures as a set of linguistic phenomena depending on interlanguage conditions. Now, we will explain those conditions, and, we will also describe the definition of linguistic rules and replacements which define the linguistic phenomena.</Paragraph>
    <Paragraph position="11"> structure linguistic_phenomenon; parts: rules: set (instance (linguistic_rule)) I set (tuple(replacement-rule); properties: type: function(type of the rules or replacements associated to each phenomenon) description: string; global: boolean; lexical_entry: set(instance(morpheme)); axioms: If global=False then lexical_entry = &lt; &gt; Martxalar, Diaz de Ilarraza 8J Maite Oronoz 52 Computational Model off Interlanguage structure interlanguage_condition; parts: linguistic_context:</Paragraph>
    <Paragraph position="13"> Which kind of conditions must be considered in the interlanguage? We said above that, inside the interlanguage, language structures are context-dependent or context-independent (Selinker, 1992). Referring to context-dependent structures it is very important to differentiate between two types of contexts: non-linguistic and linguistic.</Paragraph>
    <Paragraph position="14"> Non-linguistic conditions are related to a discourse domain. Interlanguage varies depending on the domain. The linguistic structures that we activate when writing a story are different to those we activate when we write scientific-technical texts (thematic_conditions). Activity types, such as fielding questions, writing a letter, translating a sentence, conversing in a group etc. are also non-linguistic conditions.</Paragraph>
    <Paragraph position="15"> Interlanguage forms can vary from one activity type to another, even though the discourse domain is the same. The activity types can be related to the structure of the whole text (text_conditions); in addition there are also some non-linguistic conditions (e.g. length of the sentence) related to a particular language structure in the text (structure_conditions). For example, sometimes students mark agreement between verb and complements in small simple sentences, and, at the same time they forget it in long sentences. In our case, structure conditions are studied by means of the corpus; text conditions, however, are detected by means of interviews with the teachers and learners.</Paragraph>
    <Paragraph position="16"> concept condition; subtypes: linguistic_condition, non_linguistic_condition; properties: description: string;  concept linguistic_condition; subtype-of: condition; properties: word_level: llst (part_of_speech, declension_case ... ) sentence_level: list (use_of_subordinates ... ) concept non_linguistic_condition; subtype-of: condition; subtypes: textual_condition, thematic_condition; concept textual_condition subtype-of: non_linguistic_condition; properties: text_conditions: list (summary, formalJetter, translation ... ); structure_conditions: list(long_sentence_based, long_word_based, apl_place_lem, apl_place_mor ... );  concept thematic_condition subtype-of: non_linguistic_condition; properties: type: (general, technical); Linguistic conditions are studied by means of a corpus. In the corpus composed of texts written by high level and upper intermediate language students (350 texts collected between 1991 and 1995) we found linguistic influence in some language structures of the interlanguage. For instance, the presence of plurality of some components in the sentence can cause verbs to agree with such components, whether or not these must be in agreement with the verb (the phenomenon of plurality has also been observed in second language learners of French (Lessard et al., 1994)). Finally, we would like to claim that this way of putting linguistic structures in context could be applied similarly when modelling first languages.</Paragraph>
    <Paragraph position="17"> After defining which kind of conditions must be taken into account when linguistiq phenomena are identified, we will see which type of linguistic rules can be found inside the phenomena.</Paragraph>
    <Paragraph position="18"> It is usual that language learners know only some linguistic rules corresponding to a particular linguistic phenomenon, and not all of them. In the case of language natives, however, they know, in most cases, all linguistic rules. That is the reason for representing explicitly in the student's interlanguage the set of linguistic rules related to the linguistic phenomena of the language structure. In other cases, as in natives, it should not be necessary to make their linguistic rules explicit as the linguistic phenomena define, implicitly, the set of linguistic rules. In the same way, we could say that linguistic rules identify the corresponding linguistic phenomenon, Martxalar, Diaz de Ilarraza ~ Maite Oronoz 53 Computational Model of Interlanguage however, it is necessary to make it explicit, as a linguistic phenomenon could be detected in a student's interlanguage, but the linguistic rules would not be identified until after some interactions with the student. The student model is dynamic, so, the language structures are also dynamic. Therefore, in the first interactions with the student a linguistic phenomenon can be detected inside the student's interlanguage before eliciting the corresponding linguistic rules. Next we shall define the structure of the linguistic rules.</Paragraph>
    <Paragraph position="19"> structure linguistic_rule; subtypes: morphological_rule, syntactic_rule; parts: implemented_by: set (rule. identifier); cardinality: rain 1; conditions: set(instance (interlanguage_condition)); properties: type: {morph, syn}; description: string; example: string; stabilization: {rarely, sometimes, usually, always}; In the experiments the teachers have identified three types of language phenomena in the students' interlanguage: first, simple interlanguage structures composed of a set of linguistic phenomena and linguistic rules; second, avoiding interlanguage structures defined as linguistic rules that the student usually avoids; and, third, replacement language structures where the learner uses a structure too often (or rarely) instead of using other structures (e.g. when a person uses the conjunction and all time and rarely uses structures such as however, nevertheless, thus ... ). Consequently, we can say that there are relationships between linguistic rules of the interlanguage. That is why structures which represent linguistic phenomena also have a set of replacement tuples, which represent the replacement relations between linguistic rules.</Paragraph>
  </Section>
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