morphology

Meaning: In the language topic of psychology, morphology is the structure of words. A morpheme is the smallest unit of meaning. Free morphemes can stand alone (cat, run). Bound morphemes must attach to another morpheme (un-, -ed, -s, -ness). "Unhappiness" has three morphemes: un, happy, ness. Children pick up morphological rules, and overgeneralizing them produces errors such as "goed" or "foots." Those errors suggest the child is applying a rule, not just imitating what they heard.

On the MCAT: Expect questions that sort the components of language: phonology (speech sounds, phonemes), morphology (word structure), semantics (word meaning), syntax (sentence structure and word order), and pragmatics (use in social context). A passage may describe a child's speech error, an invented word, or a prefix or suffix, and ask which component is involved. Overgeneralization errors are often used as evidence in language-acquisition arguments.

Common confusion: Students mix up morphemes and phonemes. "Cats" has four phonemes (k, æ, t, s) but two morphemes (cat and the plural -s). A single sound can be a morpheme, and a morpheme can have several syllables. Morphology is also not syntax: morphology works inside words, while syntax orders words in sentences. In biology, morphology means the form or shape of an organism or cell, such as bacterial shape.