Fossilization
Fossilization (Selinker 1972) refers to the permanent cessation of Interlanguage development in specific linguistic features, despite continued exposure, motivation, and opportunity. The learner's interlanguage stabilizes prematurely — certain errors become fixed and resistant to correction.
What It Looks Like
Fossilization is feature-specific, not global. A highly proficient learner may have fossilized errors in one area while continuing to develop in others:
- A Vietnamese learner of English who consistently drops articles (I went to store) despite years of immersion
- A French speaker who never fully acquires the English /h/ sound
- An advanced learner who alternates between correct and incorrect past tense marking — the incorrect forms resurface under pressure (a phenomenon called backsliding)
Backsliding is a diagnostic clue: if errors reappear in unmonitored speech (when tired, excited, or speaking fast), the correct form was likely never fully acquired — only controlled through conscious monitoring.
Proposed Causes
| Factor | Mechanism |
|---|---|
| L1 transfer | Deeply entrenched L1 patterns persist. See Language Transfer |
| Communicative sufficiency | The error does not impede communication, so there is no pressure to fix it. "Good enough" stops development |
| Lack of feedback | Without Corrective Feedback, the learner receives no signal that the form is wrong |
| Sensitive period effects | Some features (especially phonology) may be constrained by maturational factors. See Critical Period Hypothesis |
| Automatization of errors | Wrong forms get practiced and automatized just like correct ones — practice does not distinguish |
| Input quality | Exposure to non-standard input (other L2 speakers) reinforces non-target forms |
Stabilization vs Fossilization
Long (2003) argued that true fossilization — permanent, irreversible cessation — is difficult to prove. Most cases might be better described as stabilization: prolonged lack of progress that could potentially be reversed with the right intervention. The distinction matters because stabilization implies hope; fossilization implies a ceiling.
Why It Matters for Teaching
- Prevention is easier than correction. Establishing accurate forms early (through Focus on Form, models, and feedback) is more efficient than trying to undo fossilized patterns later.
- Some errors are more fossilization-prone than others. Features with low communicative load (articles, third person -s, prepositions) fossilize more easily because getting them wrong rarely causes misunderstanding.
- Corrective feedback must be persistent and salient. Occasional correction is unlikely to destabilize fossilized forms. Focused, sustained attention to specific features — what some researchers call a "noticing blitz" — may help.
- Acceptance may be appropriate. Not all fossilized features need to be fixed. If communication is clear and the learner's goals do not require native-like accuracy, investing effort elsewhere may be more productive.