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[on:]

Hello,

Reaction time experiments are widely used in psychology. For serious use, it's important to have a very accurate measuring device. Standard keyboards are not made with timing accuracy in mind, so psychologists use special 'response boxes', such as this one: http://www.pstnet.com/hardware.cfm?ID=102
It's very accurate, but it works only with special software, connects via serial port, needs drivers, and - it's pricey.

I'm guessing the new Leonardo could be made into a nice, accurate reaction time measuring device. The most user-friendly way would be to make leonardo emulate a keyboard, so it could be simply plugged in.
Also, some low-bounce buttons should be used.

So, does someone know lag-times for the leonardo - how much time does it take from pressing a button on the arduino to computer receiving the button-press signal? If it is long - could it be made shorter?
How about low-bounce button designs?

Thank you.

[Reply #1 on:]

Oh, by the way, RT is usualy measured from stimulus onset (e.g. a picture on the screen) to key press.

Or, if the subject keeps one button pressed and reacts with another button, then there are two times - from stimulus onset to key1_release, and from key1_release to key2_press.

[Reply #2 on:]

What kind of resolution do you need? 1ms? 0.1ms?

I suspect the most difficult part will be characterizing the latency of the USB comm from PC to arduino. Specifically, how will the arduino know with accuracy when the stimulus was presented. I know USB protocols vary widely in their timing allowances, but not exactly what the leonardo is capable of.

[Reply #3 on:]

About 1 ms accuracy would be enough.

The arduino does not have to know when the stimulus is pressed.
Software measures the time from stimulus onset until key press on a keyboard, or on the response box (the arduino).

A better idea (more accurate) would be sincronize Arudino and PC clocks and then have the arduino record exact keypress and keyrealease time, and just send a char with a timestamp.

But then I would need a special driver for the device, and special software to use it.

I'd like to keep things simple and just make the arduino emulate a keyboard.

[Reply #4 on:]

maybe this class can help a bit - http://www.arduino.cc/playground/Code/StopWatchClass -

Why not let the Arduino signal the PC to start the test . Then you can measure timing in micro seconds ==> definitiely in millis().

[Reply #5 on:]

What's wrong with dropping a meter stick trick? Psychologists can't do math? Just google for a youtube video. It's super easy and costs you nothing.

[Reply #6 on:]

Psychologists can't do math?

It is more complex. With the invention of the digital calculator many people (not only P.) got worse in math as they delegate their math abilities to a machine / program.

The next ability humankind will loose change is memory (instant fact knowledge). People delegate more and more of their knowledge to the internet. Instead of remembering a fact they remember the pointer to that fact. Broken links will cause amnesia