According to the text, about what percent of the adult population either maintains a stable level of intellectual performance or increases their performance well into their 70s?

LTD may be an important mechanism in modifying the memories and___old memories to free synapses of new information.

Fill in the blank(s) with the appropriate word(s).

A primary difference between the nativists' and the social interactionists' models of language development is that unlike nativists,

A) social interactionists believe that any exposure to verbal or written language is enough to activate the language acquisition device. B) social interactionists do not believe that humans are biologically wired to develop language. C) social interactionists believe that the primary milestone necessary for language development is an understanding of object permanence. D) social interactionists believe that children must have conversations with other people in order to develop language.