Illustration by Son of Alan

The Parts

A) 9-volt battery: Generates a weak 1.5-milliampere current

B) Regulator: Allows researchers to control the electrical juice

C) Nylon cap: Houses electrodes that measure electrical activity in the brain

D) Anode: Directs current through the skull to the medial frontal cortex of the brain

E) Cathode: Terminates electrical current in the cheek

Scientists at Vanderbilt University developed this literal thinking cap to test the notion that a mild current applied to the medial frontal cortex—a brain region that governs adaptive behavior—can speed up learning. “It sounds a bit like snake oil, but electrical-chemical signals are what thoughts are made of,” says neuroscientist Robert Reinhart. “We’re using the language of the mind to ask the question, Can we control the controller?”

This article originally appeared in the August 2014 issue of Popular Science.