Processability Theory
Why does “he go” survive every lesson on third-person -s?
Processability Theory, developed by Manfred Pienemann, holds that learners can produce only the grammatical structures their developing language processor can handle, so structures emerge in a predictable, implicational order.
Many English teachers know this pattern. A learner in Hà Nội marks plurals (cats) and past tense (walked) yet keeps saying he go long after third-person -s has been taught, drilled and tested. Processability Theory explains this in terms of processing, not effort or memory.
Manfred Pienemann’s Processability Theory (PT) starts from a premise: learners can produce, and so acquire, only what their language processor can handle at a given point. Drawing on Levelt’s model of speech production and formalised in Lexical-Functional Grammar, it describes a hierarchy of processing procedures, each a prerequisite for the next. Early on, learners mark information on single words, such as plural -s on a noun. Later they must pass grammatical information between words, first within a phrase and then across phrases, as when the person and number of the subject must be matched on the verb in she walks. Last comes the distinct word order of subordinate clauses, as in I wonder what she wants. PT counts a structure as acquired when it first emerges in systematic use, not when it becomes accurate.
Pienemann’s (1984) teachability hypothesis proposed that instruction helps only learners ready for the next stage. The evidence is mixed. In Spada and Lightbown’s (1999) classroom study of English questions, readiness did not predict who gained from instruction in the way the hypothesis expected. Pallotti (2007) added that the emergence criterion, PT’s test of acquisition, needs a clearer, more explicit definition.
None of this makes late structures pointless to teach: teaching pays off most readily near the relevant stage, and learners’ interlanguage use of late structures may lag well behind the lesson.
In actionOne learner’s questions over a term
Week 2: You like football? · Week 6: Do you like football? Where you go yesterday? · Week 12: Where did you go yesterday?
An invented illustration. Intonation questions come first, then fronted do and wh- words without inversion, then inversion, broadly the order described for English questions.
In the classroom
- 1
Profile before you plan: record a learner retelling a story or asking questions, and note which structures appear systematically, even with errors, to estimate their current stage.
- 2
Target the next step: if learners still ask You like it?, practise fronted questions such as Do you…? before expecting inverted forms like Where does she live?, using brief focus on form in meaningful tasks.
- 3
Keep exposing learners to late structures such as third-person -s, but assess them patiently, looking for emergence over months rather than accuracy after one unit.
Myth and reality
If learners still make an error after it has been taught, the teaching or the learner has failed.
PT predicts that some structures cannot be produced until simpler processing procedures are in place, so delay can be developmental. How rigid the stages are, and how far instruction can speed them, remains debated.
Reflect
Which structure in your current syllabus might your learners not yet be ready to produce, and what would you do differently if that were true?
Worth a minute before your next lesson, or a conversation in the staffroom.
SourcesChecked against Crossref and library records
Pienemann set out PT in his 1998 book. It built on the Multidimensional Model from research on German as a second language (Meisel, Clahsen & Pienemann, 1981) and was later extended by Pienemann, Di Biase and Kawaguchi (2005).
Pienemann, M. (1998). Language processing and second language development: Processability theory. John Benjamins.
Pienemann, M. (1984). Psychological constraints on the teachability of languages. Studies in Second Language Acquisition, 6(2), 186–214.
The original teachability study: instruction helped child learners of German mainly when they were one stage short of the taught structure.
Pienemann, M., Johnston, M., & Brindley, G. (1988). Constructing an acquisition-based procedure for second language assessment. Studies in Second Language Acquisition, 10(2), 217–243.
An early attempt to let assessors judge a learner’s developmental stage from samples of spontaneous speech.
Spada, N., & Lightbown, P. M. (1999). Instruction, first language influence, and developmental readiness in second language acquisition. The Modern Language Journal, 83(1), 1–22.
A classroom test of readiness with Quebec children learning English questions, with results that complicate the teachability hypothesis.
Pallotti, G. (2007). An operational definition of the emergence criterion. Applied Linguistics, 28(3), 361–382.
Spells out what it should take to count a structure as having emerged, a decision PT research depends on.
Pienemann, M., & Lenzing, A. (2025). Processability theory. Cambridge University Press.
A concise, up-to-date introduction to the theory, its research branches and its methods, by its main proponents.
ConnectionsSee it in the graph
- The Teachability Hypothesisnot yet writtenThe classroom prediction: instruction works best when learners are ready.
- The Noticing HypothesisNoticing a form in input does not guarantee it can be processed in output.
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