Subject: What is the current research about the tongue having four taste areas?

I am doing a science project on "Does the Human Tongue Have Definite Areas 
for Certain Tastes?" In my research I have found literature that gives 
both yes and no answers. A RWA Linden, Br Dent J 1993 stated that " The 
idea of there being specific regions of the tongue(sweet on the tip,salt on 
the front edges,sour on the rear edges ,and bitter on the back) is a 
popular misconception based on the early studies on relative sensitivities. 
The regional sensitivity differences are quite small."  When I attempted a 
taste test on myself, I noticed that it was not that clear where I tasted 
sweet and salty. What is the current thinking on there being distinct taste 
areas on the tongue? Thank you very much!

Re: What is the current research about the tongue having four taste areas?