The T-unit as a measure of 'syntactic maturity': operationalizing linguistic complexity in early generative grammar

In 1964, American language educator Kellogg W. Hunt (1912–1998) proposed that the average length of what he called the ‘T-unit’ in a text could quantify its syntactic complexity. Hunt defined a T-unit as a main clause plus any modifiers or subordinated material. His research showed that average T-units increased incrementally with age in texts written by students in grades 4, 8, 12, and adult writers. Capitalizing on a mid-century vogue for linguistics, Hunt interpreted this finding in the idiom of 1960s transformational-generative grammar as indicating that writers gradually learn to impose syntactic transformations on simple sentences, resulting in more complex syntactic structures. Teachers, educational researchers, and applied linguists continue to employ the T-unit, long outliving its initial theoretical warrant.