"Customers looked at the higher prices ($25 for the chicken instead of $21, $17 cocktails instead of $14) and ordered fewer and less-expensive items, even though they were paying exactly the same amount for them by tacking 20% onto the check at meal’s end."

You know what, I worry about this sometimes. We think that we're so evolved and advanced race - that we have poetry and literature, modern medicine and rocket science. That we deserve to explore the stars, and if we met alien intelligence we'd sit at the table as equals.

But turns out a normal human has emotion overriding even the simplest logic and basic arithmetic defeats most of us - I imagine it's not even just the "average" Joe - a lot of very intelligent people will see that $25 burger and decide that they'd rather go somewhere where the burger is $20, because it "feels cheaper".

Monkey sees banana, monkey wants banana. Except this monkey can build rockets and nuclear reactors.