Peter Simpson-Young wearing his Transcranial Direct Current Stimulator. Unlike most of the other experimenters – "battery-lickers", is how he derisively refers to them – he is actually a qualified neuroscientist. But he's also an enthusiast, an experimenter and a DIY-er. Hence, despite his scientific scepticism and caution, the idea of building a machine to pump electricity into his brain really excites him. And he thinks that it's actually working. That it's making him smarter. "When I've used it for 20 minutes or so, I do often feel that some things are a lot easier. Placebo or not, after use I do find that it requires less cognitive effort to do otherwise cognitively-demanding tasks." Transcranial direct-current stimulation – tDCS – involves running a very low electrical current through the brain, stimulating its nodes to higher activity.

In the past five years researchers around the globe have claimed to be able to produce a dazzling array of different cognitive benefits: improved memory, focus, calmness and problem solving ability. The American armed forces are using the technology to halve the time it takes a pilot to learn to fly an unmanned drone. In Australia, a research team is confident tDCS will eventually become a normal and widely-available treatment for depression. But with the legitimate science comes the pseudoscience, helped along by the fact that tDCS machines are extremely cheap to manufacture – a simple circuit with electrodes, resistors and a low-voltage power supply. DiytDCS.com and the OpenStim project both offer schematics to easily build a stimulator at home. This is what Peter Simpson-Young did – he simply downloaded the plans and 3D-printed the components. "We checked the output a number of times. it was accurate, it was very accurate.

"The currents that you're putting out are so small, and if you do it in a very safe way ... I wasn't nervous because I knew it was safe." That said, he used it only once before switching over to a device he bought over the internet called a Fo.Cus. Mr Simpson-Young is pretty confident in his own ability to understand the technology and its impact. He is more sceptical about the amateurs on the internet with no background in neuroscience or engineering. "There are devices online for sale that these guys are selling to each other which have current regulators which are bound to fail. They're going to put out massive current. I really hope they don't enter the public awareness when these devices start failing and kids start dying." The Fo.Cus, recommended to retail at $US200 ($260), is one of a series of consumer-oriented tDCS devices that can be found online. It's marketed at video gamers and endurance athletes under the premise it can improve concentration and focus.

While Mr Simpson-Young is a convert, others are more sceptical of the consumer devices. The Black Dog Institute, in Sydney, is running one of Australia's only clinical tDCS trials, investigating the technique as a treatment for depression. PhD student and research assistant at the institute Kerrie-Anne Ho says the trials are extremely promising, and she believes the technology will soon be widely available to sufferers. However, for healthy people, Miss Ho says she doubts the technology will have any lasting effect. "In healthy people, your brain is quite plastic anyway so there is not a lot we can do to change it. It's already working at a near-optimal level. There is more room for improvement in people with depression."

Further, how tDCS actually worked on the brain still is not well-enough understood – and messing around with it at home could be very dangerous, she says. "We don't know exactly what will happen if you change certain processes in certain ways. [Enthusiasts] are changing the current intensity, the size of the electrodes - that might produce effects they're not expecting. "If you're not quite sure what you're doing you might do something unexpected to your brain, and over repeated sessions you could produce lasting negative impacts." Some researchers worry the pseudoscience is getting ahead of the actual science – and is mining for results that can't actually be found. Jared Cooney Horvath, a Harvard student with a PhD from the University of Melbourne, completed a meta-analysis of published tDCS studies a few years ago to look at the claimed benefits. His results deeply trouble him and those working within the field.

"Lo and behold, you go through the literature and you start piecing it all together and almost nothing comes out of it," he says. "When all the data's pooled, it's just all over the map." Mr Horvath thinks researchers' understandable excitement over a low-cost treatment that seems to produce extraordinary results has pushed them into seeing things that their research data just does not support. "We all wanted this to work, it would have been so cool if it had worked, and that desire pushes us... if you really want it to work you can look at a data set and say yeah, there really is something there."