This theory started out as the Multidimensional Model, which came from work done by the ZISA group mainly at the University of Hamburg in the late seventies. One of the first findings of the group was that all the children and adult learners of German as a second language in the study adhered to a five-stage developmental sequence.
Stage X – Canonical order (SVO)
die kinder spielen mim bait the children play with the ball
Stage X + I- Adverb preposing (ADV)
da kinder spielen there children play
Stage X + 2- Verb separation (SEP)
alle kinder muss die pause machen all children must the break have
Stage X+3- Inversion (INV)
dam hat sie wieder die knock gebringt then has she again the bone brought
Stage X+4- Verb-end (V-END)
er sagte, dass er nach house kommt he said that he home comes
Learners didn’t abandon one interlanguage rule for the next as they progressed; they added new ones while retaining the old, and thus the presence of one rule implies the presence of earlier rules.
The explanation offered for this developmental sequence is that each stage reflects the learner’s use of three speech-processing strategies. Clahsen and Pienemann argue that processing is “constrained” by the strategies and development consists of the gradual removal of these constraints, or the “shedding of the strategies”, which allows the processing of progressively more complex structures. The strategies are:
(i) The Canonical Order Strategy. The construction of sentences at Stage X obeys simple canonical order that is generally assumed to be “actor – action – acted upon.” This is a pre-linguistic phase of acquisition where learners build sentences according to meaning, not on the basis of any grammatical knowledge.
(ii) The Initialisation-Finalisation Strategy. Stage X+1 occurs when learners notice discrepancies between their rule and input. But the areas of input where discrepancies are noticed are constrained by perceptual saliency – it is easier to notice differences at the beginnings or the ends of sentences since these are more salient than the middle of sentences. As a result, elements at the initial and final positions may be moved around, while leaving the canonical order undisturbed.
Stage X+2 also involves this strategy, but verb separation is considered more difficult than adverb fronting, because the former requires not just movement to the end position but also disruption of a continuous constituent, the verb + particle, infinitive, or particle.
Stage X+3 is even more complex, since it involves both disruption and movement of an internal element to a non-salient position, and so requires the learner to abandon salience and recognise different grammatical categories.
(iii) The Subordinate Clause Strategy. This is used in Stage X+4 and requires the most advanced processing, skills because the learner has to produce a hierarchical structure, which involves identifying sub-strings within a string and moving elements out of those sub-strings into other positions.
These constraints on interlanguage development are argued to be universal; they include all developmental stages, not just word order, and they apply to all second languages, not just German.
The ZISA model also proposed a variational dimension to SLA, and hence the name “Multidimensional”. While the developmental sequence of SLA is fixed by universal processing restraints, individual learners follow different routes in SLA, depending primarily on whether they adopt a predominantly “standard” orientation, favouring accuracy, or a predominantly “simplifying” one, favouring communicative effectiveness.
Pienemann ‘s next development (1998) is to expand the Multidemensional model into a Processability Theory, which predicts which grammatical structures an L2 learner can process at a given level of development.
This capacity to predict which formal hypotheses are processable at which point in development provides the basis for a uniform explanatory framework which can account for a diverse range of phenomena related to language development (Pienemann, 1998: xv).
The important thing about this theory is that while Pienemann describes the same route as other scholars have done for interlanguage development, in addition now he is offering an explanation for why interlanguage grammars develop in the way they do. His theory proposes that
for linguistic hypotheses to transform into executable procedural knowledge the processor needs to have the capacity of processing those hypotheses (Pienemann, 1998: 4).
Pienemann, in other words, argues that there will be certain linguistic hypotheses that, at a particular stage of development, the L2 learner cannot access because he or she doesn’t have the necessary processing resources available. At any stage of development, the learner can produce and comprehend only those L2 linguistic forms which the current state of the language processor can handle.
The processing resources that have to be acquired by the L2 learner will, according to Processability Theory, be acquired in the following sequence:
- lemma access,
- the category procedure,
- the phrasal procedure
- the S-procedure,
- the subordinate clause procedure – if applicable. (Pienemann, 1998: 7)
The theory states that each procedure is a necessary prerequisite for the following procedure, and that
the hierarchy will be cut off in the learner grammar at the point of the missing processing procedures and the rest of the hierarchy will be replaced by a direct mapping of conceptual structures onto surface form (Pienemann, 1998: 7).
The SLA process can therefore be seen as one in which the L2 learner entertains hypotheses about the L2 grammar and that this “hypothesis space” is determined by the processability hierarchy.
In this account of the SLA process, the mechanism at work is an information processing device, which is constrained by limitations in its ability to process input. The device adds new rules while retaining the old ones, and as the limiting “speech-processing strategies” which constrain processing are removed, this allows the processing of progressively more complex structures.
What is most impressive about the theory (it provides an explanation for the interlanguage development route) is also most problematic, since the theory takes as self-evident that our cognition works in the way the model suggests. We are told that people see things in a canonical order of “actor – action – acted upon.”, that people prefer continuous to discontinuous entities, that the beginnings and ends of sentences are more salient than the middles of sentences and so on, without being offered much justification for such a view, beyond the general assumption of what is easy and difficult to process. As Towell and Hawkins say of the Multidimensional Model:
They require us to take on faith assumptions about the nature of perception. The perceptual constructs are essentially mysterious, and what is more, any number of new ones may be invented in an unconstrained way (Towell and Hawkins, 1994: 50).
This criticism isn’t actually as damning as it might appear – there are obviously good reasons to suppose that simple things will be more easily processed than complex ones, there is a mountain of evidence from L1 acquisition studies to support some of the claims, and, of course, whatever new assumptions “may be invented” can be dealt with if and when they appear. As Pienemann makes clear, the assumptions he makes are common to most cognitive models, and, importantly, they result in making predictions that are highly falsifiable.
Apart from some vagueness about precisely how the processing mechanism works, and exactly what constitutes the acquisition of each level, the theory has little to say about transfer, and deals with a limited domain, restricting itself to an account of processing that accounts for speech production, and avoiding any discussion of linguistic theory.
In brief, the two main strengths of this theory are that it provides not just a description, but an explanation of interlanguage development, and that it is testable. The explanation is taken from experimental psycholinguistics, not from the data, and is thus able to make wide, strong predictions, and to apply to all future data. The predictions the theory makes are widely-applicable and, to some extent, testable: if we can find an L2 learner who has skipped a stage in the developmental sequence, then we will have found empirical evidence that challenges the theory. Since the theory also claims that the constraints on processability are not affected by context, even classroom instruction should not be able to change or reduce these stages.
The Teachability Hypothesis
Which brings us to the most important implication of Pieneamann’s theory: the Teachability Hypothesis. First proposed in 1984, this predicts that items can only be successfully taught when learners are at the right stage of interlanguage development to learn them. Note immediately that neither Pienemann or anybody else is claiming to know anything but the outlines of the interlanguage development route. We don’t have any route map, and even if we did, and even if we could identify the point where each of our students was on the map (i.e., where he or she was on his or her her interlanguage trajectory) this wouldn’t mean that explicit teaching of any particular grammar point or lexical chunk, for example, would lead to procedural knowledge of it. No; what Pienamann’s work does is to give further support to the view that interlanguage development is a cognitive process involving slow, dynamic reformulation and constrained by processing limitations.
Whether Pienemann’s theory gives a good explanation of SLA is open to question, to be settled by an appeal to empirical research and more critical interrogation of the constructs. But there’s no question that Pieneamann’s research adds significantly to the evidence for the claim that SLA is a process whose route is unaffected by teaching. In order to respect our students interlanguage development, we must teach in such a way that they are given the maximum opportunities to work things out for themselves, and avoid the mistake of trying to teach them things they’re not ready, or motivated, to learn.
For a good discussion of Pienemann’s theory, see the peer commentaries in the first issue of Biligualism: Language and Cognition: Vol. 1, Number 1, 1998: entirely devoted to Processibility Theory.