Morphology examines the internal structure of words and the rules governing word formation. The basic unit is the morpheme — the smallest linguistic unit carrying meaning. "Unbreakable" contains three morphemes: un- (not), break (fracture), -able (capable of). Understanding morphological structure is essential for comprehending and producing the vast vocabulary of any language, and morphological processing plays a significant role in reading, language development, and language disorders.
Types of Morphemes
Free morphemes can stand alone as words (book, run, happy). Bound morphemes must attach to other morphemes (un-, -ing, -ness, -s). Derivational morphemes create new words or change word class (happy → unhappy, read → reader). Inflectional morphemes modify grammatical properties without changing word class (walk → walked, cat → cats). Languages vary enormously in their morphological complexity: English is relatively analytic (few morphemes per word), while languages like Turkish and Finnish are highly agglutinative (many morphemes concatenated into complex words).
Morphological Processing
A key question in psycholinguistics is whether complex words are stored as wholes or decomposed into their morphological components during recognition. Evidence supports both mechanisms: frequent complex words may be stored as wholes (full-form storage), while less frequent words are decomposed during processing. The masked priming paradigm has shown that morphologically related primes (e.g., "teacher" priming "teach") facilitate recognition even when the prime is presented too briefly for conscious perception, suggesting automatic morphological decomposition.
Languages employ different morphological strategies. Isolating languages (like Mandarin Chinese) use mostly free morphemes with minimal inflection. Agglutinative languages (like Turkish) combine many morphemes into long, regular words. Fusional languages (like Russian) fuse multiple grammatical meanings into single affixes. Polysynthetic languages (like Mohawk) can express entire sentences as single morphologically complex words. These typological differences affect language processing strategies and have implications for models of the mental lexicon.