The Critical Period Hypothesis

Definition

• A maturational period during which some experience will have its peak effect on development or learning resulting in normal behaviour attuned to the particular environment the organism has been exposed to. If exposure to this experience happens after this time, it will only have reduced or no effect. (Newport)

Critical period or critical periods?

• The basic claim
• - strong and weak versions
• Evidence
• - feral children
• - child aphasia
• - deaf speakers and signers
• - L2 learning and acquisition

Evidence from the deaf: Chelsea

• Retareded or deaf?
• Hearing aid, normal capacity
• IQ = 10 year old
• Works at a vet’s, reads, writes, communicates
• Strings of words, no syntactic structure
• Utterances comprehensible in context

Evidence from sign language

• Native – clear advantage in the use of grammatical markers
• Early starters
• Late starters