| The study examined ultimate attainment in postpuberty second language acquisition and the Critical Period Hypothesis as an explanation for non-nativeness. A grammaticality judgment task acted as an assessment instrument; a subject was considered to be native-like if the individual's subtest score was greater than or equal to the mean ratings of 90% of the control group members. The native-like subtests were totaled into a nativeness score. The study consisted of 6 research questions and followup interviews with the highest scoring and lowest scoring subjects.; As a methodological innovation, the selection of Finnish-born spouses of native English speakers (N = 104) as subjects controlled background variables (amount and quality of L2 exposure, amount of L2 and L1use, education and language learning); 80% had studied EFL. 55 subjects had age on arrival of ≥16 years and had lived in USA/Canada for 20--60 years.; 88% of the control group (N = 40) obtained the nativeness score 6 or 5. The grammaticality judgments of 38% of Finnish-born subjects were indistinguishable from the judgments of the control group and contradicted the Critical Period Hypothesis as an only explanation for native-like ultimate attainment.; The findings also indicate that Age on Arrival and Age English as a Foreign Language Began are separate age of exposure measures. The best logistic regression model with 11 binary variables predicted nativelikeness with 76.9% accuracy; the significant predictors were Age English as a Foreign Language Began, US Education, and Length of Exposure, but not Age on Arrival. However, the youngest age on arrival group (12--15 years) outperformed all other subject groupings. Their performance did not decline with aging; the nativeness scores of other subjects declined as Age at Testing increased after the peak performance age.; ANOVAs for Age English as a Foreign Language Began, Length of Exposure, Total Years of Education, and Age at Testing were significant for the 104 and 55 subject groupings.; The ∩-shaped relationship between the nativeness score and Length of Exposure explains their low correlation. Age at Testing impacted on ultimate attainment by confounding with education and other background variables (prior foreign language study, second language proficiency on arrival, multilingualism, etc.). |
