Cookie cutter science

December 20, 2011 

— One of the best parts of baking for me as a kid was the process of "helping" my mama roll out and cut cookie shapes for the oven.

At this age, I know that I actually hindered her work and she was just being kind in letting me participate, but at the time I thought I was an aide in the process of transforming a lump of material into a thin sheet of ginger-rich dough that we could cut up into the barnyard animals of which I was so fond — and for which we had many different cutter shapes.

One of the goals in the overall process was to make as many ginger cookies as humanly possible from the first roll out of dough. The second roll out, because it necessarily had more flour worked into it, was considerably tougher and thicker, hence not as highly prized by anyone in the family. Indeed, when we were all done, we stored the first and second roll cookies in separate containers and ate them at different times, so great was our preference for the thinner and more delicate cookie.

Truly maximizing the number of animals you can cut from a sheet of dough and minimizing the waste bits between the animals is the sort of problem that a skilled mathematician can best address. It’s no easy task and would take more mathematical acumen than I will ever possess.

Still, anyone who has done the kitchen work by the seat-of-their-pants can appreciate that some patterns of animals yield a lot more good, first-roll cookies and less waste than do others. (Simple squares and rectangles do the best job of all, capturing 100% of the dough for first-round status, but who wants to eat such simple shapes when much more is possible?)

A second more scientific issue involves how our brains process the shapes of cookie cutters themselves. I read about it recently in The Mad Science Book by Reto Schneider.

Here’s an experiment you can do with simple cookie cutter shapes: a star, a circle, perhaps a simple Christmas tree, and the like.

First you need a friend or relation to put them all under a towel for you, so you don’t see the shapes. Next, using your fingers, you should work to identify each cutter by its shape.

If you are like most people, you’ll be quite able to accomplish the task with your fingers. Our brains, in other words, are good at using our moving fingers for such work.

But if your friend presses, say, the star shape into your palm — still under the towel — you will likely be only 50 percent as good at being able to name the shape of the cutter.

There is quite a paradox in this result. Moving fingers require the brain to sort through a heck of a lot of information. Pressing the star into the hand is really much more simple. But why can’t the brain recognize the shape better in the simpler manner?

An American researcher named James J. Gibson took up this issue in the 1960s. He recognized that the simple experiment showed something significant. He hypothesized that our brains do better as active explorers of the world around them than as passive receivers of tactile input.

One way he had of testing the idea was to press the star shape into a subject’s hand, then release it, rotate it a bit, and press it in again. The proportion of people who could recognize the star increased when he did this.

In short, the more skin disturbance, the better. Or, to put it another way, the brain does well with different and various input — it doesn’t get swamped or overwhelmed by it.

Gibson’s work led to a revision of the theory of tactile reception. We feel things and recognize them not because our brains need to examine them in the most simple way, but because our brains are remarkably adept.

In short, we are all smarter in some respects than researchers before Gibson thought. That — plus this season of homemade cookies — is the good news. * Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. Follow her on the web at rockdoc.wsu.edu and on Twitter @RockDocWSU. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.

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