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, with the incorrect forms resurfacing 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 and was 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, meaning 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.

Teaching Implications

• 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.