Response times on the USB bus

[EJ Nikelski]

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


-- 
Jim Nikelski, Ph.D.
Postdoctoral Research Fellow
Bloomfield Centre for Research in Aging
Lady Davis Institute for Medical Research
Sir Mortimer B. Davis - Jewish General Hospital
McGill University
Tel: (514) 340-8222 x 2298
Fax: (514) 340-8295