“-- the optimal time to learn a second language is between age three and five or as soon thereafter as possible, and certainly before the onset of puberty.” -- Rosalie Porter Critical Period Hypothesis

Theoretical Components of a Critical Period? Beginning and end points of the period. Qualitative difference inside and outside the period. Discontinuity at the end of the period. Robust to environmental variation inside the period.

Johnson & Newport (1989) Critical period effects in second- language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology, 21, r=-.87r=-.16

Johnson & Newport, combined across age groups.

What Kind of Theory is SES?

Hart & Risley

Hierarchical Structure of Language: Lenneberg’s Plan

Figure 12. English development as a function of school poverty status. District A.

Figure 13. Norm-referenced English scores by parent educational level, District B. LEP student mean age equivalent score is represented by the colored portions of the bar; the white unshaded portion shows the expected age-equivalent for the norming population. < High School Some High School High School or GED Beyond High School Parent Education

Figure 16. Norm-referenced English writing scores by parent educational level, District B. LEP student mean age equivalent score is represented by the colored portions of the bar; the white unshaded portion shows the expected age-equivalent for the norming population. < High School Some High School High School or GED Beyond High School Parent Education

Figure 13. Norm-referenced English scores by parent educational level, District B. LEP student mean age equivalent score is represented by the colored portions of the bar; the white unshaded portion shows the expected age-equivalent for the norming population. < High School Some High School High School or GED Beyond High School Parent Education