At least in the US, up until the 50's/60's behaviorism (which at least claims to...

At least in the US, up until the 50's/60's behaviorism (which at least claims to be based in observation) was a dominant school of thought in psychology.

http://en.wikipedia.org/wiki/Behaviorism

In the 1950's, behaviorism fell out of favor (primarily because it lacked the explanatory power for some things, especially language).