8Brain and Language3-alt - Compatibility Mode_removed (4).pdf

The Critical Period Hypothesis for Language: American Sign Language Many children who are born deaf are not diagnosed as deaf right away and therefore they are deprived of any linguistic input for many years. (This is less common in many countries nowadays because babies are examined.) Rachel Mayber...

The Critical Period Hypothesis for Language: American Sign Language Many children who are born deaf are not diagnosed as deaf right away and therefore they are deprived of any linguistic input for many years. (This is less common in many countries nowadays because babies are examined.) Rachel Mayberry and colleagues have examined the consequence of this delayed input. In one recent study they compared 3 groups of signers: • Native signers (acquired from birth) • Early ASL learners: acquired between ages 5-7 • Delayed ASL learners: acquired between ages 8-13 25 The Critical Period Hypothesis for Language: American Sign Language At the time of testing, all three groups had been using ASL for more than 20 years. The participants were asked to watch sentences being signed and determine whether or not the sentences were grammatical. • The early learners performed worse than the native signers. • The delayed learners performed worse than both the natives and the early learners. 26 The Critical Period Hypothesis for Language: American Sign Language • Age of exposure to linguistic input really matters. • The later the exposure, the worse the level of grammatical proficiency. • While vocabulary can be acquired, grammatical knowledge is negatively impacted with later exposure. 27 What did we learn from the research on the Critical Period? • We may have an innate ability to acquire language, but we require linguistic input from our environment • Must receive input within a critical period (i.e., a biologically determined “window of opportunity”) • After the critical period, humans are unable to acquire language with native-like proficiency-particularly grammar. Again, different domains are impacted differently. 28