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  #1  
Old 07-05-2002, 04:14 AM
JohnClay JohnClay is offline
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Human reflex and reaction times

Hi,
I was wondering what the average range is for reflex and reaction times and also about people with very fast or slow reactions/reflexes.
e.g. what is the normal reaction time to a visual stimulus? e.g. 400 ms? The test should penalize people who guess too early - perhaps by extending the time before the stimulus or restarting it. The test should involve a random time period before a visual change happens (e.g. a light flashes) and this could be between 2 and 4 seconds. Then they press a button as soon as they see the change. The experiment should be able to test their reaction as quickly as possible - so not much time is involved moving their muscles.
And what about the reaction time to hearing a sound? Is that similar? (e.g. 400 ms?)
What if the person is frightened by a loud sound (e.g. a dog barking) and jumps... would this reflex(?) happen quicker than if they consciously were reacting to a sound? Or does it take about the same amount of time?

And what if someone is hit near the knee with a mallet and their leg jerks? What kind of reflex times can people have? On TV sometimes people take several seconds to react... do people sometimes take a fairly long time to have their reflex in real life?

What if someone puts a super-hot thing under someone's finger? How long would it take the finger to move? Can this time vary from person to person? What about if extreme cold or a sharp pin was involved? How long would it take for the instinctive reflex to occur?

Do babies have reflexes that are as fast as adults? (like reflexes to hot surfaces, etc) If not, I am guessing that these reflexes are at least partly learnt... even though they occur non-deliberately.

I'd also appreciate any other information about the time it takes for the brain the respond physically to any kind of stimulus.
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  #2  
Old 07-05-2002, 08:18 AM
JohnClay JohnClay is offline
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Well I did some more searching on the internet and came up with these things:

http://mednews.stanford.edu/news_rel.../reaction.html
- Navy Top Gun fighter pilots typically score between 200 and 225 milliseconds
- average reaction time for the drinkers with a blood alcohol level of 0.057 percent was 263 milliseconds

http://www.stanfordhospital.com/news...pyDrivers.html
- average reaction time of the alcohol-impaired group [0.089%]was 294 milliseconds, while the average for the sleep-deprived groups was 300 milliseconds. [without alcohol their reaction is 61 ms quicker = 233 ms)

http://216.239.51.100/search?q=cache...hl=en&ie=UTF-8
"Furthermore, it is important to appreciate the speed with which a muscle response can be evoked in this exceedingly simple two neuron reflex arc....Depending on the particular limb muscles involved, the reflex time in humans is well within the range of 20-50 milliseconds"

I've found better reaction timer software:
http://sci.vu.edu.au/~drw/ranClass01.html
I get about 360 ms and sometimes get 350 ms or 320 ms. It uses JavaScript so it isn't probably very accurate. Well now I sometimes get 290 ms... I think I'm really sleep-deprived...
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  #3  
Old 07-05-2002, 08:59 AM
Aro Aro is offline
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Test your onw reflexes here.

I average about 0.24 seconds...
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  #4  
Old 07-05-2002, 10:31 AM
QueenAl QueenAl is offline
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Aro, thanks! I managed 0.16 seconds. Might try another time when I'm not so knackered.
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Old 07-05-2002, 10:49 AM
QueenAl QueenAl is offline
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JohnClay, I'm not sure about the response times of babies, but there are some reflexes that babies are born with, which fade over time. For instance, there's the grasp or palmar reflex, where a newborn baby grasps onto a suitable surface (usually your hands/thumbs) and can support its own weight. Doctors often test for this reflex to rule out certain spinal injury in a newborn - but don't try it at home! Then there is the 'stepping' reflex, whereby if you hold a baby up so the soles of its feet touch the ground, the baby will automatically make walking movements. This one should be gone by about 3 or 4 months. The 'diving' reflex is what enables that amazing underwater swimming. This one is gone by about the age of six months, but it can last longer if it's used, say if you take your child swimming and (with suitable supervision) help them swim underwater.

There are several other primative reflexes present in newborns, which you can read about Here.
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Old 07-06-2002, 12:21 AM
JohnClay JohnClay is offline
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Quote:
Originally posted by QueenAl
Aro, thanks! I managed 0.16 seconds. Might try another time when I'm not so knackered.
I don't know how well that Javascript thing works... I'll post a link to one I made soon, which gives your average response time, etc.
from http://mednews.stanford.edu/news_rel.../reaction.html
"...Navy Top Gun fighter pilots typically score between 200 and 225 milliseconds, while a reaction time of 150 milliseconds lies beyond the capability of even the Michael Johnsons and Carl Lewises of the world. For that reason, response times of less than 150 milliseconds were not counted, Powell explained...."
Either you guessed it and clicked it before you saw it, or the program has some problem with the timing, or you have amazing reflexes.
That neonatal reflex link is quite amazing... some of them, such as the Babkin one, are pretty bizarre. ("When both of baby's palms are pressed, her eyes will close, mouth will open and her head will turn to one side.")
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Old 07-06-2002, 02:50 AM
bbeaty bbeaty is offline
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I ran some "vision psychophysics" programs back in 1980, and I think my best time was around 120mS. This was for very bright flashes which occupy your whole visual field. The smaller the flashing "object", and the dimmer the flash, the slower your response time. It also varies for different colors. We were using green LEDs for everything.
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  #8  
Old 07-06-2002, 07:09 AM
JohnClay JohnClay is offline
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bbeaty:
What was your average time though? I think your average time is the most important thing. And from the quote earlier, it said that response times of less than 150 milliseconds weren't counted... could your system detect responses that were too early? If so, it should tell the people running it, and make the person wait several more seconds before the flash happens. (Restart the timer)
Maybe those experiments in those articles didn't use very intense flashes... ?
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  #9  
Old 07-07-2002, 12:38 PM
QueenAl QueenAl is offline
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Perhaps bbeaty's point about reaction time differing according to how much of your visual field the flashing colour occupies. In the link article, it says 'a red light', so perhaps that was only a dot in the centre of the screen. (For the record, my laptop screen is quite small). I definitely wasn't pre-empting the flash - I did that once and the computer told me off for 'cheating,' so it does tell if you are just guessing. However, I do have excellent reflexes in real-world situations, so maybe the test is accurate!
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  #10  
Old 07-07-2002, 01:03 PM
QueenAl QueenAl is offline
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JohnClay - right now I'm severely sleep-deprived (having been up for 34 hours now), badly hungover, hungry, drained and physically exhausted (walked about ten miles and danced for a couple of hours), so in the interests of science I tried both those reaction tests again. On the one Aro linked to, today my average was 22 seconds, and on yours, I got 330 every time (kinda surprised I got such a consistent score, but that's what it said). Yours is harder too - has a smaller screen.

From your OP: I was talking with a friend about TV reaction times not long ago, and she posited that if you see, say, a man get a gun out, shock may delay your reaction in getting your own gun out. However, I think it's just a visual technique to allow the viewer time to react to the guy getting his gun out. It's annoying when it's overlong, though. I always want to shout 'don't just stand there gawping, shoot the bastard!'

Quote:
What if the person is frightened by a loud sound (e.g. a dog barking) and jumps... would this reflex(?) happen quicker than if they consciously were reacting to a sound? Or does it take about the same amount of time?
I don't have a cite (though I did look for one), but I do remember from college psych classes being told that expectancy does improve reaction times. There are also certain 'alarm' sounds we innately respond to more quickly than others, which is why police and fire engine sirens are now at those particular frequencies and modulations, which are similar as those of howling wolves. So in your example, the alarm signal we perceive in a dog's bark might improve the reaction time despite the lack of expectation.
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  #11  
Old 07-09-2002, 05:30 AM
JohnClay JohnClay is offline
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http://members.ozemail.com.au/~wenke...actiontime.htm

Here is a reaction tester I made - the code is based on the link I gave earlier. The screen colour changes and it shows the average time. My average is usually about 210 ms and my quickest has been about 180 ms. There is a fairly long delay before the flash and I think that is good to make sure you don't guess it by chance... it also records the number of trials and number of false starts, etc.

As far as the dog's bark goes, I think it is mainly the loudness that would make me jump... e.g. in horror movies they make you jump just by having some tension and then there is a big visual change and a big sound....
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  #12  
Old 07-09-2002, 08:05 AM
QueenAl QueenAl is offline
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That's a good one, JohnClay, I like having the highs and lows as well as the average. You're right about the longer delay lessening the chances of flukes. My highest was 170, my lowest 100, my average 123.42 (I most often got 110), and no false starts. That's on two hours sleep last night.

You know there's a thread in, I think MPSIMS, about reaction times, an offshoot of this thread?
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