Simple cumulative timing question

[FrankBank]

 Hi Scott, I'm just wondering where you saw in the E-prime documentation to 
set the duration less than (rather than exactly) at some multiple of the 
refresh rate?  Maybe I'll try doing that as well.  My (perhaps faulty) 
understanding of the E-prime documentation is a little different.  I 
thought what happens when you set the duration to less than an exact 
multiple of the refresh cycle is that you end up with a percentage of your 
trials displayed at the +1 refresh cycle and -1 refresh cycle that bounds 
that chosen duration.

So, say you used 90 ms in your case.  Your upper bound refresh cycle is at 
100ms and lower is at 100-16.7 = 83.3 ms.  The distance of your chosen 
duration from these two points determines the percentage of trials that 
will be of either the lower or higher duration.  So then:
90 - 83.3 = 6.7 ms.  Then divide that by the refresh cycle: 6.7/16.7 = 
40%.  Since it is  40% of the distance between refresh cycles you'd end up 
with 40% of your trials at 100 ms and 60% at the low end of 83.3 ms.  If 
you used 95 ms instead you'd get 95 - 83.3 = 11.7 and 11.7/16.7 = 70% so 
70% of your trials would be 100 ms in duration and 30% at 83.3 ms.  That is 
how i read it anyways, would be very interested to hear others thoughts!  

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