system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a taste equivalent of olfactory fatigue?

I was chatting with another engineer at work about a time when I worked in a lab and someone cracked open a bottle of mercaptan to draw off a sample.  They opened the bottle too much.  We didn't smell anything after a few seconds, but the neighbors across from us reported a natural gas leak to the fire department.  

In relaying this story, we got wondering: is there an equivalent to olfactory fatigue for taste?  What kind of things would trigger it (spice, etc.)? 

Thanks!
gpt
This phenomenon is called sensory adaptation, and it's pretty common in all sensory systems, even vision. That's what makes those illusions where you stare at a fixed point in a reverse-colour image and then see a true-colour image work. Or, if you stare at a fixed point and keep your eyes perfectly still, your vision will quickly start to grey out. Try it! It's hard, your eyes are always moving for exactly this reason.

Yes, it can definitely happen on the tongue, but it's less common to experience it because your mouth is usually being constantly flushed with saliva, washing stuff away so that what's in the next bite will contrast with the absence of taste. This is, in fact, why water has a sort of taste of its own: It tastes different than saliva, because saliva has a specific mixture of electrolytes and other stuff in it.

This can't really happen with a smell that's everywhere around you, because there's no fresh air to contrast the smell against. 

Long story short, our sensory systems are best at detecting change / contrast.