how has the definition of social faciliation evolved over time

Since this is not my specific area of expertise, I searched Google under the key words "social faciliation evolution" to get these possible sources:

http://www.google.com/search?client=safari&rls=en&q=social+facilitation+evolution&ie=UTF-8&oe=UTF-8

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.