Helle Lykke Nielsen
Research in the field of English as a second language (and, to a much lesser extent, German and French) has tried to explain the order of acquisition with regards to surface structures, such as e.g. morpheme order, as well as to markedness theory.  Both approaches have been met with severe critism as to their methodological approach as well as to their conclusions.  However, in recent years, there has been a growing focus on cognitive operations as the main factor of explaining how and in what order language learners acquire a foreign language: An important theoretical construct in this area is Manfred Pienemann's Teachability Hypothesis in the framework of which he establishes a language processing hierarchy of four levels, none of which can be jumped in the acquisition process. 
The fact that studies of acquisition order in second language acquisition have moved from the level of language specific surface structures towards a more cognitive approach, makes it interesting to try to apply these to Arabic as a foreign language, since cognitive structures are supposedly the same, no matter what foreign language we are dealing with, whereas language specific structures are not. Therefore, what I would like to do in this study is to see if Pienemann's language processing hierarchy can explain learner language data from students of Arabic. The question which I intend to answer can be stated as follows: Is there an order of acquisition for Arabic as a foreign language which can be explained according to cognitive operations?
The study will be structured as follows: In the following section, Pienemann's language processing hierarchy, I shall outline, in a rather sketchy manner, the premises and characteristics of the language processing hierarchy. In section 3, A language processing hierarchy for Arabic as a foreign language, I shall apply the hierarchy to Arabic, so as to see what the theory predicts to be the order of acquisition for noun phrase structures. They have been chosen because they are well suited to illustrate some of the cognitive operations implied by Pienemann's theory. In section 3, I shall also compare the predicted order of acquisition to a longitudinal study of a Danish language learner of Arabic, so as to see if the data are consistent with Pienemann's model. In section 4, the findings will be discussed, and some conclusions will be presented in section 5.
Pienemann's theoretical outline is most often exemplified by the acquisition of word order rules in German. This does not mean, however, that the language processing hierarchy applies to this phenomenon only: Though the explanatory approach to the theoretical outline originated from the Zisa group of Meisel, Clahsen and Pienemann,  which focused on the order of acquisition for German word order rules, the scope was extended by Pienemann and Johnson,  so as to encompass a wider range of structures in morphology and syntax, which were then tested for German and English as second languages. In the words of Pienemann, the language processing hierarchy "serves as a general grid for the prediction of acquisitional chronologies for a wide range of structures in morphology and syntax".  Also, it should be noted that the data presented by Pienemann have been collected over the years in formal (classroom) as well as natural settings. 
Pienemann's language processing hierarchy is based on certain premises, four of which shall be dealt with here, because they are necessary to understand how the hierarchy works. The first one has to do with psychological complexity: According to Pienemann, a foreign language learner's acquisition of linguistic structures depends on how complex such structures are from a psychological point of view. Pienemann defines the term of psychological complexity as being the extent to which the language learner must "re-order and re-arrange linguistic material in the process of mapping underlying semantics onto surface forms". 
The notion of psychological complexity has been elaborated further into the following two premises both of which have to do with transfer of information on the cognitive level. The first of these has to do with perceptual saliency versus linguistic processing: Due to the cognitive structures of human beings, the language learner will initially organize his interlanguage around non-language specific features which are perceptually salient, such as for example endpoints of a sentence or a word, and from there, he will then gradually build up his language specific knowledge so as to be able to process an increasing amount of linguistic structures . This premise is related to the above mentionned one in the sense that what is perceptually salient is less psychologically complex to process than structures of a pure linguistic nature.
The third premise deals more specifically with linguistic processing: It is predicted that local transfer of information is easier to process than non-local transfer . This has to do with the way the human brain stores information: During the planning process of a linguistic utterance, the language learner (or any native speaker, for that matter) encodes his intentions into a linguistic form which is realized as linguistic output. The information which is not immediately realized is stored in the working memory so as to be ready for use at the right moment. This storing process takes place on many different levels, often at the same time: When a language learner intents to realize an utterance like, for example, "he speaks", the use of the personal pronoun "he" is to trigger the information that a third person singular pronoun requires an "-s" at the end of the verb. Thus, while the verb is realized, the "-s" morpheme has to be kept in the working memory and realized immediately at the end of the verb. Another example of this storing process takes place during the realization of a sentence like "Before he went away, he had a cup of tea": The natural order of events are so that the person in question has a cup of tea and then goes away. When the utterance is realized, however, the speaker will have to retain, in his working memory, the utterance representing the first natural event, while realizing the second part of it. Thus, the premise here is that the language learner will be able to handle local morphology before non-local morphology, since the latter will have to be retained for a longer time in the language learner's working memory, thus leaving less space to other processing devices such as e.g. recall of vocabulary.
And finally, the fourth premise concerns the relationship between the different stages of the language processing hierarchy. According to Pienemann, there exists an implicational relation between the different levels of the hierarchy in the sense that the processes which are acquired at one level are considered a necessary prerequisite for the processing of structures at the following level. Or as Pienemann puts it: "The devices acquired at one stage are a necessary building block for the following stage" . Thus, no level can be jumped in the acquisition process, since learners are unable to process structures more than one step beyond their current level.
Pienemann's language processing hierarchy consists of four levels which the language learner must pass on his way towards the mastering of a foreign language. At the first level, the language learner is not able to organize the lexical material into categories - that is, into word classes - and therefore, he has no acces to the phrase structure. Thus he cannot "identify elements within the sentence from which information has to be taken or to which information has to be brought" . In other words: Since the learner cannot index lexical items in the foreign language, no transfer of information can take place.  Learner language utterances at this level typically consists of a string of morphologically independant words. Only word order plays a role, in the sense that the learner uses the words in the order which he expects them to be sequenced in the foreign language. Pienemann terms this phenomenon "the canonical word order" .
At the second level, the language learner is able to transfer information on the basis of features which are not language specific, that is, on the basis of perceptual saliency such as endpoints (initial or final) of sentences. However, since the language learner is still not able to organize the lexical material into categories, he cannot yet insert morphemes in the phrase structure . As in level one, language learner utterances at this level typically consists of a string of morphologically independant words, but the word order can now be manipulated in such a way as to move or add words at the sentence initial or final position.
At the third level, the language learner is able to organize some of his lexical material into categories, that is, he can index some, if not all, lexical items according to word classes, which makes it possible for him to identify sentence internal constituents.  However, given the language processing devices available to the language learner at this point, he can only transfer information into "the computionally easier salient positions".  This means that the target point of the transfer will have to be the initial or the final position of a constituent or a word. In case a constituent consists of two or more words, it is predicted that the transfer of information into the endpoint position of a constituent is easier to perform than one whose insertion point is in an intraconstituent position: In the case of the former, the language learner has to identify the "insertion point by a recognition of the formal syntactic class of the element undergoing the morphological process" . In the latter, all the elements of the constituent must be recognized so as to enable the learner to locate the correct insertion point of the transfer.  At this level, we will find transfer of local morphology, e.g. inside a constituent,  whereas transfer of information into non-local environment, such as inter-constituent transfer (i.e. subject-verb agreement ) cannot take place. 
At the fourth level, the language learner will experience no more constraints on his transfer of information. He can now recognize all the elements in the sentence, and this gives him acces to the whole phrase structure in such a way that he can identify all possible elements within the sentence from which information has to be taken or to which information has to be brought . Thus, at this level, we will find transfer of information in sentence internal positions of non-local nature, e.g. between constituents (i.e. subject-verb agreement) as well as between sentences, such as concord of tenses, subordinate clauses etc.
The four levels of the language processing hierarchy can be summerized as follows:
Now, what does the language processing hierarchy predicts to be the acquisition order of Arabic? In this study, I shall examine four different noun phrase structures in Arabic, namely the indefinite noun phrase consisting of a noun and an adjective, the definte variety of the same structure, the demonstrative noun phrase and the idafa structure, or the genetive of possession. These structures have been chosen for two reasons: Firstly, they offer the possibility of comparing different cognitive operations implied by the theory. And secondly, as it is important to compare the language processing hierarchy to the input factor, so as to see if there is a correlation between the two which might eventually undermine the theory, noun phrase structures are a suitable mesuring instrument, since they are often taught at an early point in most teaching material.
In order to understand the operations which will be analyzed below, a few remarks on the linguistic structures of Arabic might be in place for readers with no prior knowledge of Arabic. Because the longitudinal study on which the following analysis is based, consists of data from a Danish learner of Arabic, a Danish translation will be provided in each case, thus making it possible to compare learner data with the learner's mother tongue.
There is no indefinite article in Arabic; the Arabic word bait thus equals "a house" ("et hus" in Danish). If the word is to be made definite, the article al is added as a prefix (and written as a part of the Arabic word), thus resulting in al-bait, "the house" ("huset" in Danish). If an adjective is to be added, it must be placed after the noun, and if the noun has the article, the adjective must also have it: Thus, bait kabir means "a big house" ("et stort hus" in Danish), whereas al-bait al-kabir takes the meaning of "the big house" ("det store hus" in Danish). Further, if the noun is feminine, (the only genders in Arabic being the masculine and the feminine), the adjective must agree with the noun; this is done by adding a ta' marbuta, an "-a", at the end of the adjective, such as in bint kabira "a big girl" or al-bint al-kabira , "the big girl".
A definite noun can be made demonstrative by adding the pronoun of hadha (masc) and hadhihi (fem) in front of the definite noun, as in hadha al-bait "this house" ("dette hus" in Danish) or hadhihi al-bint "This girl" ("denne pige" in Danish). As for the idafa structure, or the genitive of possession, it follows the English pattern of "the house of the girl" with the very important exception that a noun followed by a genitive must not take the article. "The house of the girl" thus becomes bait al-bint in Arabic (whereas in Danish, the pattern is always that of "the girl's house", "pigens hus"). For reasons of simplicity, I shall only deal with the definite idafa in this study.
Pienemann's language processing hierarchy predicts the following order of acquisition for the four noun phrase structures:
The question is now: Does this predicted order of acquisition correspond to the way language learners acquire noun phrase structures in Arabic? In order to give at least a tentative answer to this question, I have recorded the performance of a Danish language learner of Arabic on video while she was doing different oral tasks such as interviews, role plays and presentations of different subject matters in Arabic. The language learner, who is a student of Arabic at the cand. negot. programme  at Odense University, Denmark, was recorded 9 times during a period of 15 months, as from the end of her first year throughout her second year of studies. She was chosen for this study because she was one of the most successfull learners of the class in terms of high scores in written as well as oral tests.
Before comparing the predicted stages of acquisition with actual data, it is necessary to clairify the learning objectives of the course which the language learner took. This is important so as to establish an eventual relation between the input and the acquisition order. The language learner was taught Arabic on an average of 6 hours a week for a period of 4 semesters. She was taught by four different teachers during this period, three of whom were native speakers of Arabic (Egyptians), whereas one was Danish. The teaching was conducted exclusively in Arabic from the third month onwards, and the teaching material used was al-kitab al-asasi vol. 1 and 2 , which constituted the learning objectives of the course. Also the language learner went, for a period of 6 weeks, to a summer school in Tunisia during the semester break between the second and third semester.
As to the noun phrase structures chosen for this study, the learning objectives of the course were as follows:
X indicates that the structure is drilled in the exercise section of the lesson, i.e. there is a conscious attempt to teach the structure;
(X) indicates that the structure is not drilled in the exercise section, but that it occurs more than 5 times in the lesson, be it in the text, the exercise or the grammar sections.
(0) indicates that the structure is not drilled in the exercise section, and that it occurs 5 times or less in the lesson
For reason of space, the lessons have been grouped according to when recordings took place. For week 1- 25 , i.e. before recordings took place, lessons are grouped according to the teaching objectives of al-kitab al-asasi vol..1.  Though the overall picture remains clear despite the grouping of the lessons, one should notice that there are, in fact, variations in the frequency of the use of noun phrase structures in the lessons which are grouped together, especially in the first part of the teaching material: As for the <N-adj> indef, for example, the structure is mentionned twice in lesson 2 (grammar section), once in lesson 4 (text section), twice in lesson 5 (text section) and three times in lesson 7. There is no drilling of this specific structure, but there are exercises on the conjugation of nouns in the masculine and feminine as well as conjugation of nisbe adjectives, which together constitute the building blocks of the <N-adj>structure. The same kind of pattern holds true for the <N-adj> def which is used once in lesson 2, 3 and 6, whereas in lesson 9, it is used more than 5 times. As in the <N-adj> indef, there is no drilling of the <N-adj> def in the exercise sections, but the building blocks of nouns and adjectives are there.
As for the demonstrative NP, it is not used very often in the text (e.g. twice in lesson 6, once in lesson 12, three times in lesson 23), nor is it drilled explicitely, apart from lesson 4, where the language learner, in five exercises, is asked to transform sentences from the pattern of hadha al-bait lii into a pattern of hadha baitii. Idafas, however, are very frequently used as from the first lessons onwards, and are drilled accordingly.
The following table provides information on the acquisitional order of one language learner on the chosen noun phrase structures. It should be noticed that, following the criterias used by Pienemann, the data only include productive utterances, whereas imitations and word-by- word repetitions of teacher and learner talk are excluded.  The numbers represent the percentage of correct answers out of the total use of the structure, whereas brackets indicate that the structure is produced less than 5 times. As for the /, it indicates that the structure is not produced once. Thus, 0.5 indicates that half of the produced structures were correct; (1.) indicates that all of the structures produced were correct, but that it was produced less than 5 times.
It is important to keep in mind here that these data are the result of the language learner doing production tasks under (normal) communicative pressure. When communicating, the language learner often experiences a difference between knowing a rule and using it, i.e. between metalinguistic awareness and language use. Therefore, a low score in the use of a given structure does not, per se, indicate that the language learner does not "know" the rule underlying the correct language use . A low score might as well be an indication of a wide gap between knowing and using, between competence and performance .