Interlanguage
Interlanguage (IL) is the term coined by Larry Selinker (1972) for the evolving linguistic system that L2 learners construct on their way toward the target language. It is neither the L1 nor the L2 but a system in its own right, with its own internal logic.
Key Properties
- Systematic — IL has consistent rules, even if they differ from the target language
- Dynamic — it changes over time as the learner progresses
- Variable — learners may use correct and incorrect forms in the same conversation
- Permeable — open to influence from L1, L2 input, and the learner's own hypotheses
Developmental Sequences
The most important finding from IL research for the PPP debate: learners acquire grammatical structures in a predictable order that instruction cannot alter.
Key findings (Ortega, 2009):
- L2 learners exhibit common patterns across differences in age, L1, acquisition context, and instructional approach
- Acquisition is gradual, incremental, and slow — sometimes taking years
- Development shows plateaus, regressions, U-shaped curves, and zigzag trajectories — not the smooth linear progression that a synthetic syllabus assumes
- "Instruction cannot affect the route of interlanguage development in any significant way" (Ortega, 2009)
The Teachability Hypothesis (Pienemann, 1985)
Manfred Pienemann's Teachability Hypothesis states that instruction can only promote acquisition if the interlanguage is close to the point where the structure would be acquired in a natural setting. In other words:
- Teaching a structure the learner is developmentally ready for → accelerates acquisition
- Teaching a structure the learner is not ready for → ineffective, no lasting acquisition
- Instruction cannot change the order of acquisition, only the speed
This directly challenges PPP and synthetic syllabuses, which present structures in a pre-determined sequence based on perceived difficulty or textbook logic, rather than on learners' developmental readiness.
Evidence for Natural Orders
Research on morpheme acquisition orders (Dulay & Burt, 1974; Bailey et al., 1974), negation stages (Schumann, 1979), question formation (Pienemann et al., 1988), and relative clause acquisition (Eckman et al., 1988; Gass, 1982) all point to predictable sequences that hold across different L1s, ages, and instructional contexts.
Instructed learners follow the same order as naturalistic learners but tend to progress further and more rapidly (Ellis, 1984; Pavesi, 1986). This supports Form-Focused Instruction in general but undermines the specific assumption of PPP that structures can be taught in any order the syllabus designer chooses.
Implications
| Assumption | PPP / Synthetic Syllabus | What IL research shows |
|---|---|---|
| Learning sequence | Determined by syllabus | Determined by developmental readiness |
| Progress curve | Linear | U-shaped, zigzag, with plateaus |
| What learners learn | What is taught | What they are ready for |
| Role of instruction | Determines route | Accelerates rate, cannot change route |
This is why Geoff Jordan and other TBLT advocates argue that a synthetic syllabus built on the assumption of linear, teacher-controlled progress is fundamentally at odds with how L2 acquisition actually works.
References
- Selinker, L. (1972). Interlanguage. IRAL, 10(3), 209–231.
- Pienemann, M. (1985). Learnability and syllabus construction. In K. Hyltenstam & M. Pienemann (Eds.), Modelling and Assessing Second Language Acquisition.
- Ortega, L. (2009). Understanding Second Language Acquisition. Routledge.