A new strategy might help (Image: Wade Griffith/Getty)

Ever wished you could think more laterally to solve a problem? In future, maybe you’ll just use a bit of mind-boosting technology: zapping the brain with electricity helps people think outside the box to solve a task.

Transcranial direct current stimulation (tDCS) is a safe and non-invasive method of temporarily altering the activity of neurons by passing weak currents through electrodes on the scalp. It can enhance mathematical skills, memory, attention and language learning.

Richard Chi and Allan Snyder of the University of Sydney in Australia wondered whether it would help people solve brain-teasers. They began by training 60 volunteers to solve arithmetic problems expressed in Roman numerals constructed from matchsticks. The point of this was to get their brains in the habit of solving problems in a particular way: the participants corrected false calculations by moving matchsticks around to create different numbers.


The volunteers then worked on two further matchstick problems that required a different approach, swapping an equation’s symbols, such as “−” and “÷”, while they received tDCS over their anterior temporal lobes (ATL), brain structures found on each side of the brain near the temples. Chi and Snyder focused their attention on the ATLs because the right-hand one is known to be involved in perceiving the world in a new light.

Some participants received an excitatory current over the right hemisphere of the brain and inhibitory current over the left, while others experienced the opposite pattern or a sham treatment.

Stimulating solution

Excitation of the right hemisphere and inhibition of the left made the participants three times more likely to figure out the correct answer within 6 minutes compared with those who received the sham treatment.

The authors say this result confirms that the right ATL is associated with insight and novel meaning. It also backs up previous findings that the left ATL is involved in processing routine strategies and the maintenance of existing hypotheses. The combination of excitation and inhibition may force participants to examine problems with fresh eyes instead of relying on old routines, say the authors.

“It’s intriguing when brain stimulation leads to improved performance, because typically you find that this type of manipulation is disruptive,” says Jonathan Schooler, a psychologist at the University of California, Santa Barbara.

Schooler says that the tDCS could have disrupted the strategies and cognitive processes used to solve the first set of calculations, and that this helped the subjects switch to a new strategy more effectively. The authors should use additional tasks to determine whether stimulation of the ATL affects other forms of insight, he says.

Journal reference: PLoS One, DOI: 10.1371/journal.pone.0016655