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Variables

There’s always more to the story. Take Pavlov’s dogs. The great Russian physiologist, who won a Nobel Prize for his research into…By Kevin Berger

There’s always more to the story. Take Pavlov’s dogs. The great Russian physiologist, who won a Nobel Prize for his research into the physiology of digestion, seldom rang a bell to reveal dogs could be conditioned to anticipate a reward of food. In experiments to illuminate the digestive and nervous systems of mammals, Ivan Petrovich Pavlov was a master at controlling variables to produce surprising and sophisticated results. In his book, The Ten Most Beautiful Experiments, science writer George Johnson informs us Pavlov proved dogs could anticipate time, discriminate between an object moving clockwise or counter-clockwise, and distinguish between notes on a musical scale.

In one amazing experiment, Pavlov was determined to control every possible variable that could affect the outcome, and so placed dogs in a soundproof chamber. He played a dog four notes in ascending order and gave it food. No reward was forthcoming when the notes were played in descending order. The dog quickly learned to tell the simple melodies apart and salivated at the ascending order. Further, Pavlov showed, a dog could distinguish between the ascending and descending melodies when the notes were played in 22 combinations. Pavlov’s dogs were ready for Juilliard!

Controlling variables in search of a hypothetical result is one of the most important methods in science. And this month in Nautilus we spotlight how variables inform experiments in a range of scientific and cultural fields. But the concept of variables is not limited to methodology. A variable is a reminder that a shift in perception can spring us from cliché and deepen our knowledge and understanding.

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