A good example of a paradigm shift was the Copernican Revolution where the Sun became the center of the Solar system! For extra credit - which picture below is correct?
If you get it wrong - you may be burned at the stake!

It is argued that Psychology has gone through many competing paradigms such as the Introspectionists, Humanists, Behaviorists, Cognitivists and more. The only reason that no psychologist has been burned at the stake is that there are laws.