See your alpha waves (maybe)

[Mesozoic Mister Nigel]

This is neat and fun: http://blogs.discovermagazine.com/neuroskeptic/2013/08/21/can-you-see-your-own-brain-waves/#.UhdRE5LVDka

[McGrupp]

Neat! I asked a couple of neurologists wandering around today about this. Both had no idea if it's alpha waves or not but think it's a possibility. They also think it's really neat too.

I would think it would be challenging to estimate the frequency of the illusion, although comparing them to other fixed wheels may make that easier.

Secondly, the authors say that perceiving the illusion (not just seeing the physical wheel) causes increased alpha waves:

I can try to test that! Perfect excuse to hook up my neurosky again.

[Mesozoic Mister Nigel]

Neat! I asked a couple of neurologists wandering around today about this. Both had no idea if it's alpha waves or not but think it's a possibility. They also think it's really neat too.

I would think it would be challenging to estimate the frequency of the illusion, although comparing them to other fixed wheels may make that easier.

Secondly, the authors say that perceiving the illusion (not just seeing the physical wheel) causes increased alpha waves:

I can try to test that! Perfect excuse to hook up my neurosky again.

Cool!

[Telarus]

Interesting. I wonder if this is related to the buddhist "wall staring" where you get swimmy 'artifacts' like that.

[rong]

I would bet this has something to do with the brain's sampling rate.  The article states that alpha waves are generally around 10Hz.  I believe early films were made at 24 frames per second (Hz). 

Google Nyquist sampling rate or Shannon Sampling theorem for more in depth description.

But I'm thinking the rate that the image flashes for an individual is directly related to that individual's own sampling rate.

Another good indication of your own brain's sampling rate is the illusion of wagon wheels appearing to slow down and change direction as they actually increase in speed.

[Reginald Ret]

I would bet this has something to do with the brain's sampling rate.  The article states that alpha waves are generally around 10Hz.  I believe early films were made at 24 frames per second (Hz). 

Google Nyquist sampling rate or Shannon Sampling theorem for more in depth description.

But I'm thinking the rate that the image flashes for an individual is directly related to that individual's own sampling rate.

Another good indication of your own brain's sampling rate is the illusion of wagon wheels appearing to slow down and change direction as they actually increase in speed.

Huh. 3 days ago  I was just thinking about my vision refresh rate.
Interesting subject.

[rong]

glad you found it interesting.  that last post was via phone, so i didn't want to put the time in to talk about nyquist sampling rate, but . . . now i'm at my lappy 386 and will add (for those who don't like to google things) that the nyquist sampling rate is double the highest frequency in the signal.  the shannon sampling theorem states that, in order to perfectly reconstruct a sampled signal, it must have been sampled at the nyquist sampling rate - or double the highest frequency present.

if you try to reconstruct a signal that was sampled at a lower rate, then you get something called aliasing.  I believe the wagon wheels appearing to turn backwards is an example of aliasing.

24 frames per second (Hz) was figured out to be fast enough to trick the brain into perceiving fluid motion instead of the appearance of discrete still shots.  I think it's relevant that 24 Hz is slightly more than double 10 Hz (the frequency of Alpha Waves).  BUT - this isn't quite what shannon's sampling theorem is about.  In this case, the signal being sampled is double the sampling frequency - kind of shannon's theorem backwards.



i had an acquaintance who speculated that certain psychedelics slow down the brain's frame rate (which I believe is akin to the brain's sampling rate) and that your brain "fills in the gaps" between samples.  This was where, he believed, hallucinations came from.  With a lower frame rate, you have longer gaps to fill in. 

One thing I've noticed pertaining to my vision's refresh rate is that whenever I first look at a clock with a second hand.  the first tick on the second hand seems to take a lot longer - in a sense it appears the clock was waiting for me to look at it before it started ticking and it takes the clock a little while to notice.  I know this isn't the case, but i think this has something to do with how my brain's "video card" works.


As an aside:
What about music, you say?  Can't people hear up to 20,000 kHz?  yes they can, but the ears are technically an analog to digital converter apparatus.  Certain parts of the ear are resonant to and excited by different frequencies.  So, you don't perceive the frequencies directly.

It would be interesting to know what the highest perceivable BPM would be.  I would guess it's somewhere around 300 BPM (300= (10Hz/2)*60 Sec)

[GrannySmith]

damn, i could see some vague pulsing but not really a strong flickering effect. I'm totally exhausted though, so I'll try again tomorrow...

[The Good Reverend Roger]

I don't want to see my brain.   

[Mesozoic Mister Nigel]

Make sure you're looking far enough away from the image... maybe start near it and scan away until you get flickering.

I was intrigued by the researchers claim that the flickering increases as you do it.

[Mesozoic Mister Nigel]

I don't want to see my brain.   

BUT YOUR BRAIN LOVES YOU!

[The Good Reverend Roger]

I don't want to see my brain.   

BUT YOUR BRAIN LOVES YOU!

No, no, I think it's been pretty well established that my brain hates me and is plotting to kill me. 

[rong]

"I used to think my brain was the most interesting part of my body.  But then I thought 'look who's telling me that' " -Emo Philips

[The Good Reverend Roger]

"I used to think my brain was the most interesting part of my body.  But then I thought 'look who's telling me that' " -Emo Philips

My alpha waves probably form goatse or something, just in case I ever look.

[Mesozoic Mister Nigel]

"I used to think my brain was the most interesting part of my body.  But then I thought 'look who's telling me that' " -Emo Philips

My alpha waves probably form goatse or something, just in case I ever look.