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May 03

Playing with EEG Display for Neurosky Mindwave Mobile

EEG Display For Neurosky Mindwave Mobile

In the spring of 2013 I have built a fairly simple app that does ElectroEncephaloGram (EEG) analysis:¬†EEG Display for NeuroSky MindWave Mobile. It is an iPhone/iPad app that plots EEG data in real time from my Neurosky headband. I’ve long known about brainwave bands, and being able to take a look at mine with a 130$ headband seemed too good to pass up.

The defining feature of Neurosky is its ability to output raw EEG data at about 512 Hz. A stream of raw numbers can be continuously sent to an app via Bluetooth. The first order of business was plotting this data and making sure that the graph is fast enough to actually display data without delay. With some iOS magic I was able to get graphs both on iPhone and iPad to show up without delay.

EEG Display For Neurosky MindWave Mobile Proper Operation

This is the correctly setup headband outputting raw data. Top graph shows last second of data. Bottom graph shows 90 seconds of data

So far I had over 20 people try it, and the results have been very encouraging. I don’t know if the app is novel or cool, but people seem to like it. In fact, so many people have tried the headband over the course of the last couple months that I started to sanitize the headband between users.

The special “Brain Activity Index” algorithm, originally developed for sleep studies is very responsive to changes in the raw EEG signal and helps people understand that something is happening. The EEG signal comes in very fast – at 500 data points per second, and while you can visually see that the waveform has changed, it’s off the screen in half a second, and it’s hard to quantify what it was.

With the Brain Activity Index algorithm, the app has a cyan “Scored” line at the bottom of the graph. The line goes up and down, and stays up long enough to see changes in brain/facial muscles activity. This makes it very easy to see that something is going on in the brain.

Here’s documentation for the EEG Display app

EEG Display for Neurosky MindWave Mobile in action

Current discoveries

In the couple months that I’ve been experimenting with the app, people have pointed out a number of interesting phenomena:

  • Conversation changes the brainwave ¬†pattern (listening or talking) (Phil’s hypothesis)
  • Looking at the screen with a head turned produces elevated pattern due to muscular activity
  • Blinking and swallowing produces clearly visible artifacts
  • Genuine smiling produces different waveform than “fake” smiling.
  • Chewing on grape skin produces a unique waveform, different from regular chewing
This is the headband

This is the headband

 

What are next steps?

The new update is coming out soon, and it will make the iPad version better – larger graphs with more history, so waveforms that clip the top of the graph on iPhone would be clearly visible.

Another update that might happen within the next few weeks is adding an iPad in server mode. It works like this :

  • a headband is connected to an iPhone through Bluetooth
  • multiple iPhones/iPads can be connected to an iPad via wifi
  • iPad displays brain activity index for connected devices side by side.

This “multi-user” mode of operation offers possibility of new kinds of brainwave games, or could be used for research purposes.

 

 

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