Thresholds of Human Action Potentals and Debouce Times

[Butterfingers]

Alot of time has been spent these days arguing how fast is too fast and what constitutes cheating in electronicly controlled paintball markers...

Many companies nowadays try to pass electrical noise off as genuine shots to the point that one pull does not equal one shot anymore.

There are two factors that determine the recovery time for a nerve cell to send an impulse to a muscle such as your finger. These two factors are called absolute and relative refactory periods. Eventhough nerve pulses can be very fast around 2/10 ths of a millisecond. The recovery between nerve impuses can be much longer.

Nerve cells act like mini capacitors sodium potassium pumps pump posively charged ions to one side of a membrane as a negative charge accumulates on the opposite side.

When a nerve fires its action potential it is similar to discharging a capacitor. Its charge gets released and induces other nerves to fire or a muscle to contract.

A refractory period can be compared to the charging time of a capacitor.

As mentioned before there are 2 types of refactory period that contribute to this "refactory period" or "charging time" of a nerve cell.

These are:

Absolute refractory period: This is due to the inactivation of all Sodium Channels. Your nerve ABSOUTELY CANNOT accept another impulse. Meaning that during this period you can jolt your nerve with infinity voltage and it will fail to fire. This has been determined to be about 2ms.

Relative Refactory period: This is the time that it takes for the nerve cell to recover to the point that it will fire a signal strong enough (a threshold signal) to induce a movement or action. Before this period of time Sodium Channels may be active BUT the cell has not accumulated enough charge to fire an effective action potential. This period is around 5 ms.

So there we have it 7ms for a "cycle" of the nervous system. JUST FOR THE IMPULSE! If you add the time it takes for the muscles to actually move the finger it is likely to be longer.

Now thoughts on debounce times... many seem to claim that having a debouce of 1 or 2 ms allows the computer to pick up shots "missed" when your finger twitches. Its has been shown here that a finger cant twitch that fast!

Therefore if you shoot faster with a debounce of 1ms as compared to 7ms its not one shot per pull. The gun is doing the work for you. You are either picking up electrical noise or a "state of the art" program is adding shots here and there.

Food for thought!

This should be retitled how cheater boards work and get away with it!

[Miscue]

For one finger... but what about with two fingers or raking? What if we have hyper-tensile hummingbird tendons, eh?

[Butterfingers]

Thats pretty much for any impulse that needs to be processed. In order to coordiate you 2 fingers in a way that produces an effective action many more than one consecutive and parallel impulses need to be fired extending the time.

It may be easier to fire fast with 2 fingers but physyologically the fribulation (uncontrolled contraction) of one muscle is faster than the coordiation of 2.

A hummingbird flaps its wings 75 beats per second a nerve impulse cycle is still faster at the theoretical limit at around 143 impulses per second.

[NJPaint]

Just to add to your post, muscles are much slower than nerve impulses.

Even if yout double your speed by walking, you fingers have a finite speed that they can recover and pull again at.

[Butterfingers]

Absolutely. The actual time for the desired action is MUCH MUCH longer. A way to measure it is to induce a finger spasm or fribulation and measure the rate. This is synonymous to free cycling and measures the actual time for all the processes together. The nerve impuse is just one peice of the puzzle.

Debouce setting should be called "rate adjustment for how much work the board does for me!"

[MrWallen]

I can see it now, a new product that you attach to your hand. It sends electrical pulses into your two fingers, causing them to spasm and "pull" the trigger.

[hitech]

Originally posted by MrWallen
I can see it now, a new product that you attach to your hand. It sends electrical pulses into your two fingers, causing them to spasm and "pull" the trigger.

I'm surprised no one has trid this. Then again, maybe they have...

[rx2]

Reminds me of my days back in physiology lab, twitching frog gastrocnemius muscles to summation and tetanus on the old smoke-drum kymograph. What a wretched apparatus.

Even an external apparatus sending impulses to your muscles will fail to generate twitches beyond a certain point, at which the muscle cannot get enough ATP to the fibers to break the bonds that cause contraction. When this happens, the muscle begins to cramp, and tetanizes. I have been trying to find reliable data on the threshold of summation for fast-twitch muscles in the human finger in order to caclulate a theoretical max at which one could pull a trigger.

But, I should add researchers have recently gotten a primate, in the lab, to control a mechanical arm directly with its brain, via electrodes connected to it. Imagine the day when you may interface your marker to your own neural network and fire off rounds simply by thinking about pulling the trigger. It would also shorten (VERY slightly)the time needed to snap-shoot, or the delay between the thought of pulling the trigger and the actual event, as electrons are conducted through wires at a faster velocity than impulses are conducted through even the myelinated neurons.

[AGD]

God I love the smart guys on AO!!!

Thanks Butters!!!!!

AGD

[RRfireblade]

Sorry Butters,my fingers are still faster than that.Just ask any rush hour driver that's been in front of me.



Jay.

[BarryTolar]

[Mag Master 04]

wow, i am really impressed! (NOT THAT I COUNT) i really found this thread interesteing and it IS food for thought. i just wish i understand fully what you all are talking about...i mean i get the basic concept of this but i still have a lack of knowlege here. see public schools dont teach anything like this, i guess i will have to wait till collage next year to learn things like this. all in all great post, i like to read things like this, keeps me interested in the whole concept of the ROF debate and cheater boards

[ShooterJM]

Ok I'll go through and see if I can find out any real data.

There was some experiment done in the 60's or 70's that figured out the average human reaction time. I think it was measured to be (from eyes to finger movement) .16 seconds.

But you should be able to figure it out. An estimate anyway. Have someone hold a yardstick or ruler above your hands (your hands at zero). Have them drop it (with no warning) and mark where your hands grab. Do it about a dozen times. That should give you a decent sample. Granted with walking it'll be quicker, but I don't know if it's enough.

Keep in mind during stress and complex situtations your reaction time actually increases, I THINK by 33% for a guy and 36% for a girl. Like I said, I'll see if I can find the report.

EDIT: http://www.ocf.berkeley.edu/~issues/...nexercise.html

This says reaction time can be maintained but doesn't say improved with exercise.

[Butterfingers]

Granted you cannot test every human being but modern science has found so far that this is the average right in the middle of the bell shaped curve.

There may be some faster or some slower but not my much... On top of that you still need to factor in the time for the muscle to actually contract.

This blanket statement as you call it covers 99.7 percent of the population but as with everything probably states that you cannot be 100 percent certain.

To those 0.3 percent I apologize

Although I cannot tell you what your reaction time with 100 percent accuracy is I can probably estimate your "refactory Period" to a relative degree of accuracy to be around 7 MS.

Reaction time as you speak of is not what im talking about, is diffrent and concerns may other processes and vary greatly. However your reaction time requires the firing of at least more than one action potential so I can say with confidence that it is MORE THAN 7ms.

Pacemakers are set diffrently to match the rate of stimulation necessary to circulate blood in the body. Smalller heart or bigger body you need to pump more... The reason why pacemakers are set diffrently has little to do with refactory periods.

Since refactory periods have to do with sodium and potassium gated channels which are gentically similar almost identical in the species it would be safe to say that the "blanket statement" is valid.

Saying this "blanket statement" is incorrect is saying that physics is incorrect because we havent tested every object in the world... or fired every peice of matter out of a cannon to test its projectile properties.

[MrWallen]

EDIT: Gah, butters posted at the same time as me, this is directed at Jester.

But that's reaction time, like say if you saw an opponent at the last second and needed to try to shoot them. With the trigger pull you already know when and what is going to happen.

Edit: I'm also suprised that no one has come up with a handheld trigger pulling device, which would be able to pull the trigger faster than fingers, which would, of course, be unrestricted by nerves speed and instead restricted by electronics.

Barry: You have some good points, but Butters' data is only an example, or "Food for thought" as he put it.