Re: difference between sensitive period&critical period in development?

The term "sensitive period" in childhood development appears to be used in 
different contexts.  Some people use the term "sensitive period" to describe a 
newborn infant in the period just after birth, when the baby is bonding with 
the parents.  Others call toddler age (around 2 years old), the "sensitive 
period," because the toddler is extremely sensitive to the "outside world," and 
needs more security and explanations,as well as a more planned and predictable 
lifestyle and schedule.

The "critical period" term is used in specific regard to language development.  
There had been research in the past that proved basically, that "old dogs can't 
learn new tricks," and that acquisition of language had to occur by a specific 
age.  If it did not, then under that theory, a person could not learn a second 
language completely fluently if they did not learn it by that predicted age.

However, with modern neuroscience research, it is now known that the brain does 
maintain plasticity (ability to learn) throughout a person's lifetime, and 
there is no longer a set "critical period" for learning language.  Most of 
the "critical period" research was based on a time before modern neuroscience.  
It is now known that what people used to call the "critical period" was 
actually a problem in learning a second language, or even a complete first 
language, due to other factors, including hearing loss (problems in acquiring 
auditory phonetic and phonemic sounds), visual problems (including visual 
coordination, tracking, convergence, and other low vision difficulties that 
were not usually tested prior to behavioral opthalmology procedures), and also 
lifestyle problems (older individuals are not usually in a lifestyle that 
permits continual language learning, and they are also more susceptible to the 
avoidance of mistakes or errors out of fear of embarassment, which is 
termed "the affective filter").  

For more information, try the web browser at http://www3.metacrawler.com .  Type in 
your phrase, click the "phrase" button, and then do your search.

Good luck on your research project, and regards from The Mad Scientist Network.