all custom helper modules being made available to all controllers without a call to helper?

I have three different helper modules in my helpers directory
(authentication_helper.rb... etc). In my views and partials I have
calls to them but application_controller never directly calls the
method #helper directly (as in helper AuthenticationHelper or
helper :layout)...

Shouldn't calls to those methods return a method not found error
unless I explicitly call helper?

My apologies, I should have mentioned my environment in my first post:
Rails 3 tracking git
Ruby 1.9.2-rc1