Mental Workload Study

[aybanersz]

Greetings, James! I hope you are well.

I am an industrial engineering student aiming to specialize on the field of cognitive ergonomics, particularly dealing with mental workload.

Hence, as I just procured the Muse 2 device and made use of your Mind Monitor application, I am just curious on how to be able to identify the average amplitude (in terms of µV) of each of the brain waves?

In my study, my thesis panel members want to know the implications of each brain waves' quantitative values.

However, I could not find any study that makes use of "bels" which was the unit used in your website; thus, not allowing me to utilize the average alpha, beta, delta, theta, and gamma values (which are all in terms of bels) in the graphing online section of your website as seen below.

Screenshot 2024-07-21 at 9.14.51 PM.png (200.46 KiB) Viewed 4136 times

But on the brighter side, I saw a study that made use of the amplitude (in terms of µV), such that it states the following:

Alpha:
Too much alpha (>50 µV) means that the person is under the state of daydreaming, inability to focus, and to relax.
Too little alpha (<30 µV) alpha means that the person is experiencing anxiety, high stress, and insomnia.

Beta:
Too much beta (>20µV) means that the person is on the state of being tired, anxious thinking, and active concentrations.
Too less than (<20µV) means that the person is experiencing depression and poor cognition.

Delta:
Too much delta (>200 µV) means that there are brain injuries, learning problems, inability to think, and severe ADHD.
Too little delta (<100 µV) means inability to rejuvenate the body, inability to revitalize the brain, and poor sleep.

Gamma:
Too much gamma (than 3-5µV) means that the person is under the state of high arousal and stress.
Too little gamma (than 3-5µV) means that the person is under the state of depression, and learning disabilities.

Theta:
Too much theta (>30 µV ) means that the person has an ADHD, hyperactivity, impulsivity, and inattentiveness.
Too little theta (<30 µV) means the person is under the state of anxiety, poor emotional awareness, and stress.

Source:
https://www.dlsu.edu.ph/wp-content/uplo ... II-027.pdf

Hence, from the csv file that was generated from the use of Mind Monitor, how would I be able to identify the average amplitude (in terms of µV) for each of the brain waves?

Thank you very much!

[James]

The RAW EEG is measured in Volts, but the brainwaves are the power spectral density within a specific frequency range, so not Volts.
Bels can be used as a unit for anything that is the result of an FFT calculation, as is the case here.

RAW EEG (V) -> FFT -> Bin grouping -> brainwave value.

[aybanersz]

Greetings, James!

[A.] Could you expound on what "bin grouping" is all about?

[B.] Since you mentioned that "Bels can be used as a unit for anything that is the result of an FFT calculation, as is the case here," do you know any research that made use of these brain wave values (see photo below) from Mind Monitor and had their own interpretation for each brain wave values like if within the range of 70-90 bels for theta, it would be this interpretation, and if 90 bels or higher for alpha it indicates this interpretation?

Screenshot 2024-07-22 at 2.23.35 PM.png (179.07 KiB) Viewed 4070 times

[James]

*A The result of an FFT is powers in bin groups. Each bin will be a frequency range.
*B Yes, but due to my privacy policy, I am not at liberty to discuss specifics. Over the years many universities and research institutes have used Mind Monitor data in this way.

[aybanersz]

If one receives a bad-fit and good-fit marker, how would you be able to remove them in the csv file?

Is there a maximum tolerance for this? Like for example, if csv file has 2,000 data points, how many bad fit markers should be there at maximum?

[James]

I'd recommend zero. If they're at the start/end of the recording because the person isn't wearing the Muse, then it'll be pretty obvious in the data and you can just truncate to the important section you're interested in. The CSV is just a text file, you can delete rows of data by opening it in Notepad.

[aybanersz]

Going back to a previous question of mine, from the csv file that was generated from the use of Mind Monitor, how would I be able to identify the average amplitude (in terms of µV) for each of the brain waves (alpha, beta, delta, gamma, theta) in the raw EEG form?

Do I need to use EEGLAB in Matlab for this to work? Any tips.

[James]

Brainwaves are not measured in volts. That would not make sense, sorry. Once you do an FFT, the original units no longer apply.

[aybanersz]

With this in mind, do you just recommend to look at the absolute or the relative brain waves when interpreting?

Which do you think would be better? Do you have any other recommendations to maximize interpretation?

[James]

Relatives are relative to the other waves, so for example a drop in Beta Absolute will result in an increase in Alpha Relative.
Absolute and Relative are both useful measurements in different ways.