Response times on the USB bus

[Leisha Wharfield]

I'm also interested in the responses you get to this question. Input 
devices & timing are ongoing questions.

Thanks,

Leisha

EJ Nikelski wrote:

> Hi All,
>
>    I believe that I have a very simple question, although a search of 
> the E-Prime Knowledge Base (and and this List's archive) could not 
> provide me with an answer. The question is one relating to using a USB 
> mouse as a response device; specifically, can we? I am asking the 
> List, as I would like to get the opinions of researchers who (1) are 
> using various response devices - and therefore have likely given this 
> some thought, and (2) do not have an interest in trying to sell me a 
> button box.
>
>    The PST User Guide appears clear on this (page A-16), noting that 
> the approx. 100 ms response delay in addition to a std dev of 8 ms, 
> makes a mouse inappropriate when ms accuracy is required. I see a few 
> problems here:
>
> (1) I believe that the 100 ms delay is of little concern to many 
> researchers, as long as the delay is constant -- it's the 8 ms SD that 
> is of concern, as it adds unwanted noise to the signal.
>
> (2) PST used a PS/2 mouse in their tests -- most modern mice (mouses?) 
> use USB. How does a USB mouse perform? If you take a look at the 
> Lancaster University web site 
> (www.psych.lancs.ac.uk/research/reactionTimes/input.html) they seem to 
> suggest that USB mice will produce a variance in RT ranging from 0 to 
> 8 ms, which is a direct result of the 125 ms polling interval used by 
> Windows XP when sampling USB devices. This polling frequency can, 
> however, be changed, as the USB standard allows for a 1 ms polling 
> rate  (1000 Hz) (apparently, some gamers do this).
>
> (3) PST got excellent results using a keyboard as a response device, 
> which is surprising, as the sampling rate of a PS/2 keyboard is 
> actually lower than that of a USB mouse (according to Lancaster 
> University). In addition, as most modern keyboards now also use USB, I 
> cannot see how the response time of a USB keyboard would be better 
> than that of a USB mouse.
>
> (4) PST did all of their timing tests on Windows 98. The code base of 
> Windows XP shares nothing in common at all with the old DOS-based 
> Windows OSes (Win 98, 95, 3.1, etc). Timing values derived on these 
> ancient OSes cannot be extended to Win XP.
>
>
> Sorry for the lengthy e-mail, but I wanted to present my question 
> clearly. So ... what does the List think of using USB devices 
> (including both mice and keyboards) for data collection? Is anyone 
> changing their USB sampling rates prior to running subjects in order 
> to address the 125 Hz default sampling-induced response variance? How 
> are you doing this? Has anyone used some of the high-sampling-rate 
> gaming mice (e.g. the Logitech Laser mouse G5can sample at 500 Hz)? 
> Any ideas and/or suggestions would be welcome.
>
>
> -Jim
>
>