Very interesting. I'm pretty sure that we're feeding images/sounds into a very
low-level region in the hierarchy as a result of predictions at a higher level,
and that we perceive this "interference" as noise or scintillation. We do this
when the actual data does not present enough information for us to lock on to a
pattern or sequence with sufficient confidence to see or hear what we actually
see or hear. Blind people use this to navigate, using their aural
expectation/prediction of the echo characteristics of a learned space to figure
out where they must be in that space. There's clearly a capability to compare
predicted patterns (coming from up the hierarchy as well as sequence memory at
the current level) with incoming data to coerce perception into a "lock-on" to
a particular candidate perception. As this is in progress, we see fireflies and
sparks as noise, but these fade out as they're incorporated into the predicted
or expected pattern.
—
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On Sun, Sep 8, 2013 at 11:20 AM, Patrick Higgins <[email protected]>
wrote:
> The addition of noise to push low level signals
> above the noise floor is a known technique for
> making these signals perceivable. It essentially
> boost some information just below the floor above
> it, and given the brain is adept at handling noise,
> it improves the overall dynamic range of the system.
> Scintillating vision at night with dark adapted eyes
> is another example of this phenomenon. Adding in
> a little familiarity with the environment makes it easy
> make to the bathroom at night without any lights. But
> the cost of this improvement is clearly a degraded
> image with missing edges and false objects hits as
> well as an undulating video lacking smooth continuity.
> I find it interesting to learn how this process is
> implemented at a synaptic level, fascinating.
> I see it as a refinement, something that could be
> added based on the application. Such as cleaning
> up weak noisy radio transmissions, audio or video
> to bring previously unattainable information out.
> (never fails to trip me up that one of those words
> ends in dio and the other deo even tho they sound
> the same)
> This blog explains how adding (good) noise before
> something is encoded improves dynamic range. This
> might be an argument for playing with this idea at the
> encoder level.
> http://blog.discmakers.com/2013/01/dithering-adding-good-noise-to-improve-your-home-recordings/
> Taking this a little further, I use image stacking
> to reduce the noise and improve the dynamic
> range of my astrophotos. Its a common technique
> used by astrophotographers, taking many frames
> of the same object taken at different times and using
> photoshop or special image stacking software to align
> them and average each pixel. This has the effect of
> canceling the noise to some degree and adding to the
> signal. Contrast is greatly improved. Using this technique
> at the encoder level would also be a nice way to remove
> some unwanted noise (possible after it was added in for
> reasons described above). I'm wondering if these
> techniques in tandem would be worth investigating.
> Thanks TIm!
> Patrick
> On Sep 8, 2013, at 12:22 AM, Tim Boudreau wrote:
>> Thought this might be of interest on this list:
>>
>> "Release of neurotransmitter is an inherently random process, which could
>> degrade the reliability of postsynaptic spiking, even at relatively large
>> synapses. This is particularly important at auditory synapses, where the
>> rate and precise timing of spikes carry information about sounds."
>> http://www.ncbi.nlm.nih.gov/pubmed/24005293
>>
>> It suggests that the phenomenon that introducing dither noise into an audio
>> signal can improve intelligibility of low amplitude signals (pushing enough
>> samples above the noise floor that the brain will fill in the blanks) is
>> also inherently present in the brain.
>>
>> -Tim
>>
>> --
>> http://timboudreau.com
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