Biosensor Array Galvanic Skin Response Spurious Input - Revision history

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2018-04-11T19:20:13Z

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			[[Category:Biosensor Array]]

	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

Pdp7 at 19:46, 1 May 2011

2011-05-01T19:46:03Z

← Older revision	Revision as of 19:46, 1 May 2011
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Pdp7 at 19:46, 1 May 2011

2011-05-01T19:46:03Z

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	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

	== Advice on dealing with spurious input from [[Biosensor Array Galvanic Skin Response]] by [http://www.produceconsumerobot.com/truth/ Sean Montgomery] ==		=== Advice on dealing with spurious input from [[Biosensor Array Galvanic Skin Response]] by [http://www.produceconsumerobot.com/truth/ Sean Montgomery] ===



			<pre>
	---------- Forwarded message ----------		---------- Forwarded message ----------
	Date: Fri, 29 Apr 2011 14:42:57 -0400		Date: Fri, 29 Apr 2011 14:42:57 -0400
	From: Sean Montgomery <~~unknownbot01~~@gmail.com>		From: Sean Montgomery <xxx@gmail.com>
	To: Drew Fustini <~~drew~~@~~pdp7~~.com>		To: Drew Fustini <xxx@xxx.com>
	Subject: Re: GSR: eliminating spurious changes?		Subject: Re: GSR: eliminating spurious changes?

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	On Fri, Apr 29, 2011 at 2:32 PM, Drew Fustini <~~drew~~@~~pdp7~~.com> wrote:		On Fri, Apr 29, 2011 at 2:32 PM, Drew Fustini <xxx@xxx.com> wrote:

	Hi Sean,		Hi Sean,
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	---------- Forwarded message ----------		---------- Forwarded message ----------
	Date: Fri, 29 Apr 2011 14:09:40 -0400		Date: Fri, 29 Apr 2011 14:09:40 -0400
	From: Sean Montgomery <~~unknownbot01~~@~~gmail~~.com>		From: Sean Montgomery <xxx@xxx.com>
	To: Drew Fustini <~~drew~~@~~pdp7~~.com>		To: Drew Fustini <xxx@xxx.com>
	Subject: Re: GSR: eliminating spurious changes?		Subject: Re: GSR: eliminating spurious changes?

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	On Fri, Apr 29, 2011 at 1:34 PM, Drew Fustini <~~drew~~@~~pdp7~~.com> wrote:		On Fri, Apr 29, 2011 at 1:34 PM, Drew Fustini <xxxx@xxxx.com> wrote:

	Hi Sean,		Hi Sean,
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	Thanks!		Thanks!
	Drew		Drew
			</pre>

Pdp7 at 19:44, 1 May 2011

2011-05-01T19:44:57Z

← Older revision	Revision as of 19:44, 1 May 2011
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Pdp7 at 19:44, 1 May 2011

2011-05-01T19:44:57Z

← Older revision		Revision as of 19:44, 1 May 2011
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	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

	== Advice on dealing with spurious input from [[Biosensor Array Galvanic Skin Response]] by [http://www.produceconsumerobot.com/truth/ Sean Montgomery]		== Advice on dealing with spurious input from [[Biosensor Array Galvanic Skin Response]] by [http://www.produceconsumerobot.com/truth/ Sean Montgomery] ==



			---------- Forwarded message ----------
			Date: Fri, 29 Apr 2011 14:42:57 -0400
			From: Sean Montgomery <unknownbot01@gmail.com>
			To: Drew Fustini <drew@pdp7.com>
			Subject: Re: GSR: eliminating spurious changes?

			Unless you're a hardware guru, software is usually easier to quickly try out
			a bunch of analyses and see what might work. You could use the Arduinoscope
			processing library (similar to one of the ones we published in Make
			Magazine) to plot the data along with some simple analyses and detections.
			-s



			On Fri, Apr 29, 2011 at 2:32 PM, Drew Fustini <drew@pdp7.com> wrote:

			Hi Sean,

			Thanks for your fast and detailed response. We've been learning a lot
			during the short build period and existing, well-documented projects like
			yours have been a big help.

			I like your suggestion of measuring numerous locations to reject spurious
			changes. I'm imaging that would be done best in software. Is that what you
			were thinking as well?

			Thanks!
			Drew


			---------- Forwarded message ----------
			Date: Fri, 29 Apr 2011 14:09:40 -0400
			From: Sean Montgomery <unknownbot01@gmail.com>
			To: Drew Fustini <drew@pdp7.com>
			Subject: Re: GSR: eliminating spurious changes?

			Hi Drew,

			Ah, you've found the difficulties of bio-sensing... separating signal from
			noise.

			The problem you're experiencing is that when you move, you change the amount
			of contact between your finger and the electrode, thereby changing the
			resistance of the junction... exactly what the GSR is measuring. You can try
			to find a part of the body that is less likely to move during your
			behaviours of interest. I've gotten decent GSR from the wrist and not much
			success from the forehead, but fingers are the best I've found. You
			can measure GSR from numerous locations and reject spurious changes that
			only occur on one or two of the locations. You can also try to characterize
			the waveshape of real GSR responses and reject resistance changes that don't
			fit that criteria.

			Biosensing has huge potential, but is not without its hurdles. Some things
			are easier to measure like heart rate where you can more easily reject noise
			because of the stereotyped electrical signature. On the far end of the
			spectrum is EEG, where you're separating tiny electrical potentials in a sea
			of electrical noise and THEN trying to understand how those handful of
			electrical traces relate the hundreds of billions of neurons in the brain
			and the unknown (large) number of ongoing cognitive processes.

			Generally the trick is to understand your signal, what's creating it, what
			sorts of limitations that puts on your experimental paradigm. It's good to
			think about what kinds of workarounds are possible (as above), but also
			think about how you can limit the scope of your question to fit the
			attributes of the experimental tools that are available.

			Sorry no easy fix for ya. I'll be interested to know what you come up with.

			Cheers,
			Sean



			On Fri, Apr 29, 2011 at 1:34 PM, Drew Fustini <drew@pdp7.com> wrote:

			Hi Sean,

			I'm having a problem with finger cuffs which you note on the Truth
			Wristband page:

			"Note that physically moving the electrodes can create spurious changes in
			the resistance measured across the plates and contaminate our measurement.
			There are ways to work around this, but it's not completely trivial."

			I built the two-finger coper foil velcro cuffs and also the single-finger
			cuff from the wristband kit. The trouble I have from both is flexing or
			moving one's fingers generates a signal that I can't differentiate from
			actual GSR response (like poking my leg with scissors).

			Our biosensor array is design to be worn on one's body so having the hands
			motionless for accurate GSR isn't ideal. I'd really appreciate if you'd
			have any advise on how to eliminate spurious GSR readings due to movement.

			BTW, your Make co-author, Ira, pleasantly surprised me with a call to my
			desk phone to introduce an interesting biosensor data aggregation project
			he's getting organized :)

			Thanks!
			Drew

Pdp7 at 19:41, 1 May 2011

2011-05-01T19:41:36Z

← Older revision	Revision as of 19:41, 1 May 2011
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Pdp7 at 19:41, 1 May 2011

2011-05-01T19:41:36Z

← Older revision		Revision as of 19:41, 1 May 2011
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	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

	== Advice on dealing with [[Biosensor Array Galvanic Skin Response]] ~~input from~~ [http://www.produceconsumerobot.com/truth/ Sean Montgomery]		== Advice on dealing with spurious input from [[Biosensor Array Galvanic Skin Response]] by [http://www.produceconsumerobot.com/truth/ Sean Montgomery]

Pdp7 at 19:41, 1 May 2011

2011-05-01T19:41:05Z

← Older revision	Revision as of 19:41, 1 May 2011
(No difference)

Pdp7 at 19:41, 1 May 2011

2011-05-01T19:41:05Z

← Older revision		Revision as of 19:41, 1 May 2011
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	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

	== Advice on dealing with [[~~Biosensor_Array_Galvanic_Skin_Response~~ ~~GSR~~]] input from [http://www.produceconsumerobot.com/truth/ Sean Montgomery]		== Advice on dealing with [[Biosensor Array Galvanic Skin Response]] input from [http://www.produceconsumerobot.com/truth/ Sean Montgomery]

Pdp7 at 19:40, 1 May 2011

2011-05-01T19:40:42Z

← Older revision	Revision as of 19:40, 1 May 2011
(No difference)