Suzana Herculano-Houzel


My daughter asked to change her ballet classes for tap dancing – so I decided to pay the price and take a class with her and her age mates. From the very first lessons, we learned how to transform the disorganized clop-clop of the metal plates under the shoes into the rhythmic sounds of the most basic steps. And then an unusual problem arose: the desire to spend the whole day tapping my feet on the floor. I found myself with a human version of the Happy Feet penguin in the house who, instead of walking, tapped her feet – and in very noisy slippers.

The mom would have asked for silence, but the Neuroscientist on Call intervened. The metal plates have two functions in tap dancing: they turn the shoes into percussive musical instruments, operated with the feet while the rest of the body dances, and they give the brain positive feedback that it is doing the right thing. Without hearing the sound of your feet, how can you know if they are receiving the right commands from your brain at the right time and therefore learn to tap dance?

Learning depends on at least three factors: repetition, the basis of the synaptic changes that implement the new way of acting, thinking or feeling; negative feedback, which tells you when you’ve made a mistake and should try again in a different way; and positive feedback, which signals that you’ve done the right thing and should repeat it in the future.

Negative feedback is a double-edged sword. Knowing that you’re not succeeding or hearing from someone else that everything is wrong is important, but it only serves as motivation for the most determined.

What keeps us trying is positive feedback. This is so fundamental to learning that the brain rewards itself with pleasant sensations every time it gets it right. The benefit is twofold: the pleasure of getting it right reinforces the programs that worked as desired and also serves as motivation, the expectation of more positive feedback, to keep practicing. So we want to play the piano more when our fingers hit the right notes – and tap dance all the time when we hear our feet making interesting sounds. If we’re praised, even better.

Of course, it’s part of learning not to tap your feet when someone is sleeping or trying to read nearby. But at other times, not encouraging the positive reinforcement of the clop-clop of someone learning to tap would be nonsense. Instead of asking for silence, therefore, the neuroscientist on call gets up and goes tap-dancing too.

Originally published in May 2007, on Folha de São Paulo.

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