refresh rate USB

[Michiel Spape]

Hi,
Good that you thought of it. I am, however, not so sure of the weightlifter/wispy person thing. 
1. Obviously, I know the idea behind testing within subjects - all my work has been like that (until now, actually). By your own words, however, you seem concerned enough for noise within subjects - the point of the current thread. I wholeheartedly agree, in fact, that you wish the 8 ms error (which should likewise be similar between conditions) to be gone, but have argued that the motor noise will be *much* higher than this tiny bit of variance. Only, after all, if your bodybuilder will *always* take, say, 30 ms to press the button, and the wispy person, say 60 ms, you would not have a problem. This is immensely unlikely. Of course, once you have an effect, I will not say it's because of this or that, but theoretically, it should take more trials for your noise to be cancelled out by your effect.
2. The problem may be worse, though. As I'm sure you know, a lot of stuff is said to happen at a rather late stage of response processing. What if, for instance (although I agree this is unlikely), your subject is able to inhibit/speed up/etc his/her response 20 ms prior to its registration in the SRBOX - halfway between the beginning of a press and the end thereof? What I am saying is that it is conceivable that one condition (depending on where in the decision model you place your effect) might well be more affected by the heavy button than another, thus making mince of even a within-subject design.

Whether this is true or not, I think the problem can be easily circumvented by just using a very light button box.
Best,
Mich

Michiel Spapé
Research Fellow
Perception & Action group
University of Nottingham
School of Psychology
www.cognitology.eu

-----Original Message-----
From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Tobias
Sent: 08 July 2011 12:15
To: E-Prime
Subject: Re: refresh rate USB

Hi,

In fact, we do have a SRBox and I so far refused to take it because
the buttons are so hard to press. For this particular experiment I
think, however, it might still be okay, because I don't want to
compare beteween subjects, but between conditions. So the wispy girl
might have longer reaction times than the weightlifter, but the
differences between conditions should be visible for fast and slow
responders.

With the SRBox we actually have other problems too (I'll open another
thread concerning this as this seems to be a hardware problem).

ANother thing is, I just learned that a parallel port would have best
timing characteristics. Serial ports are still quite slow. Maybe we
will just use single buttons sending a signal via individual pins to
the parallel port. I have never used it but there seems to be a way of
using parallel ports in E-Prime (if you look at "devices").

Thanks a lot for your input!

BEst,
TObias

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