The Critical Period Hypothesis

Evidence from neurology

• Medical evidence: childhood aphasia
• Right hemisphere compensates for language capacity in childhood
• No such compensation in adulthood
• Controversial evidence for normal exposure and brain capacity

Processing L1 and L2

• L1 in both moniolinguals and bilinguals shows strong left hemisphere control
• In later learners (even after 7) the active brain regions processing L2 and partially or completely non-overlapping with L1 areas
• Neural organisation in late L2 is also less lateralisaed (more strategic control!!)

• Onset of L1 has great influence, onset of L2 doesn’t
• Even overhearing a language, but not speaking or using it or hearing it again can reult in native like control later in life