Keyboard Latency: Measuring subject response rates

By gkk at Fri, Feb 24 2006 10:03am |

I need to know the keystroke latency of the G4 lampshade iMacs with a wired USB keyboard. We're trying to measure response rates of subjects for cognitive psychology and need to get an idea of how much the system is dictating the response rate.

We only found one reference to something about it being 16 milliseconds for poling the USB port, but what about the keyboard scan controller, the USB circuitry, the USB itself… not to mention however fast the kernel gets around to not only polling the port but also reading the byte and then converting that into the proper driver interface.

-gkk
______________________________________________________________
Gretchen KOPMANIS, ACTC - (gkk@umich.edu)
University of Michigan, Ann Arbor
Department of Psychology MAC/UNIX Team Leader
Office: 734-763-0193 - Portable (PCS/VoiceMail) 734-717-0699
______________________________________________________________

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Tue, 2006-03-14 15:22 — Michael MacAskill (not verified)

Re: Keyboard Latency: Measuring subject response rates

Try the Psychtoolbox site: http://www.psychtoolbox.org/questions.html

Unfortunately there is a mix of new and very old content there (eg still refers a lot to ADB ports rather than USB) but there are hopefully links there that should help. They have a mailing list or discussion group that could probably give you the info you need.

Cheers,

Michael