I first observed this phenomenon in childhood, when it became clear that the taste of a grilled cheese sandwich was markedly different depending on whether it was cut corner-to-corner, top-to-bottom, or (heaven forbid) side-to-side. My preference in childhood was corner-to-corner, though in early adulthood, I went through a brief flirtation with top-to-bottom. What can I say? – it was the ’80s, and I was a habitual… cheesehead.
The food category most affected by the shape/flavor equation must surely be Snack Foods. Just stroll down the supermarket aisle and look at all the different available shapes of pretzels! And as you’re looking at them, think about the fact that you have your own preferred shape for them. The same situation exists for the Corn Chip group and the Cheese Doodle group. The actual recipes within each group aren’t much different, but our preferences as individual consumers can be incredibly strong and specific.
I should mention another class of shape variation that is far less mysterious – pasta. Most of the different pastas are made with pretty much the same recipe within a given manufacturer’s product line. But of course, the primary role of pasta is to serve as a conveyance of sauce and its components to one’s mouth, and it’s clear that these different shapes vary in their qualities as sauce transportation devices. If that isn’t clear to you, try this experiment at home: the next time you’re making lasagna, use vermicelli instead of lasagna noodles and let me know if it comes out any differently.
This mystical link between shape and flavor extends to beverages as well. The next time you’re out drinking martinis (I know, I’m assuming a lot here), have your first one in an elegant, conical martini glass. Have your second one in a Smuckers Hello Kitty Jelly Jar glass. I think you’ll be convinced that a martini ought to be cone-shaped. You may then have your third martini in the original martini glass. After that, it won’t much matter what you’re drinking them out of, as your mind will be otherwise occupied.
I suppose that for snack foods, it comes down to a question of mouth-feel, as well as a question of how much salt or doodle dust hits our tongues and palates in those first few milliseconds of eating. It’s still pretty mysterious, but at least we have a line of inquiry if we ever wanted to formally research the question. The mystery of the grilled cheese sandwich, though, lingers on.