What is 'interlingual identification'?

In Second Language Acquisition (SLA) research - building on Weinreich's (1953) work on language contact and later formalized in Selinker's interlanguage theory - 'interlingual identification' names the learner's psychological judgment that treats a native-language (L1) element as equivalent to a target-language (L2) element. It is this perceived cross-language equivalence that triggers transfer: positive transfer when the perceived match is linguistically valid, negative transfer (interference) when it is not.

Applying this to the question: interlingual identification is, by definition, the learner's judgment that something in the native language and something in the target language are similar - perceived as the same. That perceived-similarity judgment is exactly what interlingual identification denotes.

• Judging L1 and L2 elements as dissimilar describes noticing a language difference - the opposite psychological act, associated with contrastive-difference awareness rather than interlingual identification.

• L1 knowledge interfering with L2 learning describes negative transfer/interference - a possible downstream effect of a mismatched interlingual identification, not the identification judgment itself.

• Needing different abilities to learn different languages is about learner aptitude, an unrelated construct - it has nothing to do with comparing elements across the two language systems.