1. The Critical Period Hypothesis
Lynn W Zimmerman, PhD

2. First Language Acquisition
A few documented cases of children who have had difficulty developing language

3. Children as Second Language Learners
Conventional wisdom
children are better language learners than adults
Generally can master the language with little or no accent
Difficult for most adults

4. Adult Second Language Learners
Adults have more to learn than children.
expected to have a developed vocabulary
expected to use complex syntax
Generally have less time to learn a language than children
Fewer opportunities to use the language
Less social interaction
Less comprehensible input

5. Effects of Age on SLA Krashen, Long, and Scarcella (1979)
Adults proceed through the early stages of 2nd language development faster than children do
Older children acquire faster than younger children
Acquirers who begin natural exposure to second languages during childhood generally achieve higher proficiency than those beginning as adults
It appears then that children are superior to adults only in the long run.

6. Comprehensible Input
Young children receive simpler input than older children or adults.
Older acquirers
Are better able to regulate the quantity and quality of their input.
Are better at encouraging speech and at getting the speaker to modify it.
have better conversational competence than younger leaners.

7. The Monitor
Older children and adults use the Monitor more effectively than younger children.
Krashen asserts - this ability to obtain comprehensible input is the actual causative variable enabling older children and adults to acquire at a faster rate, not age itself.

8. The Affective Filter
Child’s superiority in ultimate attainment is due to the strengthening of the affective filter around puberty.
The ability to acquire is no different; the filter is just stronger, limiting input.

9. Critical Period Hypothesis
Limited developmental period during which it is possible to acquire a language, whether L1 or L2 to native-like levels.
Once this window of opportunity has passed, the ability to acquire and even learn language declines (Lennenberg, 1967).
Language learning requires more conscious effort after puberty.

10. Sensitive Period Hypothesis
CPH predicts a dramatic drop-off.
SPH argues that there is
a gradual decline.
Allowance for variation in attainment.

11. References
Freeman, D. & Freeman, Y. (2014). Essential linguistics. Portsmouth, NH: Heinemann.
Gass, S. & Selinker, L. (2008). Second language acquisition. NY: Routledge.
Krashen, S. (1981). Principles and practice in second language acquisition. Oxford: Pergamon Press.