Simple cumulative timing question

[Scott]

Sorry if I wasn't sufficiently clear. This adjustment is ONLY done for *
EVENT* timing.  In fact, what I'm asking about is how to take this into 
account, exactly what to do, when using a mixture of event and cumulative 
timings. Based on your response, I still might be saying something wrong -- 
if so, I'm sorry to to be unclear. I really thought that this ~10 ms 
'adjustment' was obvious in the documentation, though I also know that the 
documentation is old and could be outdated, and one cannot always just 
following anyone's advice, even PST's. What I'm referring to is printed in 
bold in the *E-Prime User’s Guide Chapter 3: Critical Timing* (page 99):
The equation to use for determining what stimulus duration to specify in 
E-Prime is as follows:
*Stimulus Duration to Specify = (Refresh Duration ms/cycle * Number of 
cycles) - 10ms*
Part of the reason for doing this, as I understand it, is because one can 
never assume that  the refresh rate will ever be exactly 60 hz (or anything 
else). 

This is what I meant to say, but maybe I did not, because the documentation 
that I have seen seems pretty explicit about this, for *EVENT* timing (in 
fact they explain this for most of 2 pages of Chapter 3). Now that I have 
hopefully clarified what I was *trying* to say, please tell me: Has this 
recommendation changed? If so, someone *please* explain and set me 
straight. I usually have done this (except in certain circumstances), 
starting with E-Prime 1 and continuing with E-Prime 2. Maybe you have more 
current documentation, FrankBank. What do you see for actual OTO timings in 
your data when you have used *EVENT* timing mode, across several hundred 
trials or so when setting a 100 ms stimulus duration for 100 ms? If it 
always works like that (with no extra refresh cycles), then I suppose 
there's no reason to do it differently.

On Saturday, November 10, 2012 6:00:46 PM UTC-6, FrankBank wrote:
>
> Scott, i just had one more idea about your issue.  Is it possible your 
> refresh rate is not exactly 60hz, but something very close?  If so then 
> when you set it to 100 ms and get occasional 116 ms times maybe that's 
> because the actual refresh rate of your monitor is slightly higher than 
> 60hz so that the refresh cycle x 6 = something a little less than 100 ms 
> (based on my previous post about percentages).  Then, when you drop it to 
> say 90 or 95 ms you are under the 6 cycle limit and so you start getting a 
> very high percentage of full 6 cycle duration trials.  If something like 
> this is the case than perhaps your actual multiple of a refresh cycles is 
> in the range between 95 and 100 ms and once you find it exactly you will 
> have consistent durations (somewhere in that range) across all trials.  
> Just an idea.
>

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