Markedness is the asymmetric relation between two members of a linguistic opposition, where one member (the unmarked) is more basic, more frequent, and more widely distributed across languages, while the other (the marked) is more specific, less frequent, and structurally more complex. The concept originated in Prague School phonology and was later extended to morphology, syntax, semantics, and second language acquisition.
The terms were introduced by Nikolai Trubetzkoy in his 1931 work on phonological systems and developed in his Grundzüge der Phonologie (1939). Trubetzkoy and Roman Jakobson, both members of the Prague Linguistic Circle, used markedness to describe phonological oppositions where one member carried a feature (e.g. nasality, voicing) and the other lacked it. The marked term carried the feature; the unmarked term was its absence. Voiced consonants are marked relative to voiceless ones in many languages; nasal vowels are marked relative to oral vowels.
The diagnostic indicators of markedness, as elaborated by Jakobson and later typologists, include:
Joseph Greenberg's typological work in the 1960s grounded markedness in cross-linguistic distributional facts. His implicational universals (e.g. "if a language has nasal vowels, it has oral vowels") provided an empirical basis for marked/unmarked distinctions independent of any specific theory of grammar. This typological grounding became the foundation for markedness in SLA.
Eckman (1977) proposed the Markedness Differential Hypothesis (MDH) to repair limitations of the Contrastive Analysis Hypothesis. Pure contrastive analysis predicted difficulty wherever L1 and L2 differed, but produced too many false positives: many L1-L2 differences caused no learner difficulty. Eckman's revision tied difficulty to typological markedness:
The MDH explains, for instance, why English speakers acquiring German final-devoicing have less trouble than German speakers acquiring English final voicing: voiced obstruents word-finally are more marked than voiceless ones, so the L2 acquisition of the marked direction is harder.
Eckman later refined this into the Structural Conformity Hypothesis (1991), claiming that typological universals constraining native grammars also constrain interlanguage grammars, regardless of L1-L2 differences.
Markedness has been extended to:
The concept has been criticised for vagueness: the various indicators (frequency, complexity, distribution) do not always converge on the same member as marked. Haspelmath (2006) argued that "markedness" should be retired in favour of more specific notions like frequency and structural complexity, since the unified concept obscures rather than illuminates. Others, working in Optimality Theory, have retained markedness as a constraint type, with universal markedness constraints competing with faithfulness constraints.
In SLA, the MDH retains explanatory utility for predicting where transfer will and will not surface. It is no longer the dominant framework, having been absorbed into broader crosslinguistic influence research, but the basic insight, that L2 difficulty correlates with typological markedness independent of L1-L2 difference, remains a productive heuristic.