What they actually did
Researchers led by Roi Cohen Kadosh at the University of Oxford trained people on two kinds of maths skills, rote learning simple arithmetic problems and practicing more varied calculations.
During this learning process they applied small and continually varying electrical currents to the scalp, above the temples. A control group wore the electrodes but didn’t receive any current. Compared to the controls, the people who practiced with the current turned on performed faster on the maths problems.
Even more amazing, when a subset of the participants were brought back six months later, those who had received the electrical treatment were still significantly faster, albeit only for the harder, more varied, calculations.
How plausible is it?
The particular technique these researchers used, called Transcranial Random Noise Stimulation (TRNS) is a recent invention, but the use of electrical stimulation to affect brain activity has a long history.
The brain is an electrochemical machine, so there’s every reason to think that electrical stimulation should affect its function. The part of the brain the researchers stimulated - the dorsolateral prefrontal cortex - is known to be involved in complex tasks like learning, decision making and calculation.
What’s amazing is that such a gross intervention as applying a current via electrodes, to such a large part of the brain, could have a specific (and beneficial) effect on mathematical ability.
This is technically impressive work, done by highly capable researchers at well respected institutions and published in a prestigious journal. Still, there are a few warning signs that make me nervous about how reliable the result is.
The key result showing the long-lasting nature of the effect is based on just six people who received the treatment (out of the 12 originally treated and the 12 controls). Even worse, the statistical test they rely on would have come up as “no effect” if they had done it the conventional way. While the result is based on such small numbers it has to remain as “promising” at best, rather than confirmed.
The researchers recorded percentage correctly on the maths problems, as well as speed of responding, but they only discuss the speed of responding. The graphs of errors make it look like the people who got faster also make more mistakes, which doesn’t count as an improvement in my book. Why no combined analysis of speed and accuracy?
We don’t know which part of the brain this effect is due to. Although they did record brain activity and show that it changes in the area they were interested in, the basic comparison is still “doing something to the brain” vs “doing nothing to the brain” (thanks to Vince Walsh for pointing this out). It is hard to make any solid conclusions on how this technique might be having an effect.
There was no systematic check that participants were truly ignorant of which group they were in, although the researchers believe this to be the case. If participants knew when their brain was being stimulated then the change in performance could have been due to motivation or a desire to please rather than any specific manipulation of brain function.
Putting these worries aside, we’re not going to see this technique used in the classroom any time soon, even if it holds up. Suppose this technique is reliable, and we really can improve people’s basic maths skills with a bit of electrical stimulation we’d still hesitate to deploy it. Does it affect any other skills, perhaps taking resources away from them?
Competition is a basic principle of brain development, it isn’t implausible that there would be a cost to overclocking the brain like this. There might be all sort of minor side effects such as increased fatigue or poorer attention, which would mean that stimulation wasn’t just pure benefit. Or - also plausible - perhaps the more rapid learning of the basics would mean that skills which build on those basics would be harder to learn (sort of like screenburn for memories).
I’m not worried for the participants in this research, but I’d still want a lot more questions answered before I started setting electrical stimulation along with homework.
The original paper: Snowball, A., Tachtsidis, I., Popescu, T., Thompson, J., Delazer, M., Zamarian, L., Zhu, T., Cohen Kadosh, R. (2013). Long-Term Enhancement of Brain Function and Cognition Using Cognitive Training and Brain Stimulation. Current Biology. doi:10.1016/j.cub.2013.04.045Ed
Ed Yong on the dangers of neuroscience with small data sets.
Dorothy Bishop has collected some reactions to misleading headlines about ‘shocks’).