Pedro Morais of BRAIN-COMPUTER INTERFACES over EEG Blog wrote up a post on the Brainwave Analyzer: New EEG on-line Analyser Thanks Pedro! Mr. Morais is…
Category: Brainwave Analyzer
KOB (see Gallery-KOB) noticed that the automatic gain control (ACG) doesn’t work as well in Europe. As pointed out in Noise from Electricity – Part 1 the ACG reduces any peaks caused by the electricity in the walls (60 Hz in the USA and a few other countries and 50 Hz in the rest of the world). KOB lives in Europe and if you look at his readings they do tend to have small peaks at around 50 Hz, for example “KOB eyes closed”, 5th second:
Luckily these peaks are small enough that they shouldn’t have much of an effect on the overall results. My understanding is that the Mindwave was developed in the U.S.A., and it could very well be that its ACG is more sensitive to the American 60 Hz, and less sensitive to the European 50 Hz.
Curious, I ran a test where I took off the Mindwave headset and saved the results. The Brainwave Analyzer showed a large amount of Gamma “brainwaves”. Surprised, I googled around and it turns out that EEG readers are so sensitive that they pick up the electromagnetic waves from the alternating current (AC) flowing within the walls.
| No Headset
I ran a test where I took off the Mindwave, and saved the results:
| Headset Slipped?
KOB (adult male) baseline1-relaxing with eyes open
Joël Caserus (aka Brainwave-JCP) a prolific EEG enthusiast has kindly posted a page about the Brainwave Analyzer: http://www.joel-caserus.net/brainwave-analyzer/ He also writes about the mind at:…
EEG readings are divided up in EEG bands: Delta, Theta, Alpha, Beta and Gamma (from slowest to fastest).
This is what a one second sample of brainwaves looks like when graphed:
So based on these squiggly brainwaves, how do we calculate frequencies and amplitudes?
Luckily mathematicians have come up with a solution called “Spectrum Analysis using Fourier transform”. The basic idea is that every wave, no matter how complex and irregular, can be represented by combining a number of simple (sine and cosine) waves.
5 new samples for 5 activities:
- Playing 3-D Pong http://www.ponggame.org/3dpong.php
- Watching a movie “Back to the Future” http://www.imdb.com/title/tt0088763
- Playing Concentration: http://www.mathsisfun.com/games/memory/
- Reading a novel
- Playing acoustic guitar by ear
Not surprisingly my test subject’s brainwaves were most engaged while playing guitar and must less engaged while watching a video. What did surprise me was how little his brainwaves were engaged while playing 3-D Pong. (Click on the graphs to enlarge.)
If you have access to an EEG reader, please let me know if you have similar or different results!