In the context of retrieval failures, the decay theory states that memories fade because of the occurrence of retroactive interference the cerebellum reduces in size over a period of time old memories are constantly replaced by new memories a neurochemical memory trace disintegrates over time

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

well, i can't read it so i'll ask you questions about it : )

if you were a reader and you read the introduction, would you want to read more?

does it start with a question? if so, is it something you would want to read about?

and ask any friends or family for their opinion : )