Member
Hi,
I've been through all the threads about subliminal stimuli and I've set my screen resolution to 800x600 at 75 Hz (the maximum) and changed the style to 800x600 but I'm still getting a Time n of 27 ms when I know I have had it running at 17ms in the past. What am I forgetting here?
Meg
Blair Jarvis, Administrator
Can you post your input file and a sample data log file?
Member
input file and data are attached
Blair Jarvis, Administrator
There doesn't seem to be anything unusual about your input file or data files. I would try to replicate the session another machine and see if you get the same result. If it's only on the first machine that it does this, then we can troubleshoot from there. Also, what version of DirectRT are you using? i.e., 200x.x.x?
Member
I've tried on several different computers but I get the same time n of 26/27ms. The version of Direct RT I'm using is 2006.2.0.28. I recently moved my experiment from Program files to the network drive so it can run on different computers. Can this have affected it?
Thank you
Blair Jarvis, Administrator
Can't say for sure, but we do highly recommend running DirectRT sessions locally rather than over a network for this very reason--especially when you have stimuli that need to be presented very fast. If you run it locally, does it help?
Junior Member
I also have the same problem...First I thought it was system lag...Originally Posted by Meg
Anyone can help?
ths a lot
Blair Jarvis, Administrator
Are you running the session off a local hard drive on each machine or over the network or other external location?
Junior Member
Hi, i am running it on my local hard drive...
And I have tried on different PCs, but still the time is about 26~28ms. Btw, the refresh rate i used is 75Hz.
Thank you.
Blair Jarvis, Administrator
To be sure, it can be tricky to get a image to reliably display for a single screen refresh. First check out:
http://www.empirisoft.com/support/showthread.php?t=55
and then if that doesn't help:
http://www.empirisoft.com/directrt/h...leshooting.htm
Definitely Make sure your video system has an up-to-date driver. Make sure you are using the correct driver for your monitor and not a generic driver. And then here are some other thoughts and tips:
The most conservative test is running the input file from a simpler folder on the local hard drive (e.g., c:\test) with the network cable unplugged and no other programs or processes running in the background (one quick indicator of the latter is not seeing any icons in the bottom right corner of the Windows Taskbar--or least as few as possible).
If you continue to get display times that are equal to double your refresh rate then try running the session in 800x600 resolution (as set in the Options of you .drt style file). Also check to make sure the stimulus in question is not the very first stimulus of the trial--that can cause trouble on some systems (in which case a brief blank screen can be used as an initial stimulus).
If you have checked all this (including the links above) and still can't get display times equal to a single refresh, send a zipped copy of your experiment folder to us at support@emp...com and we'll take a look at it.
Junior Member
I need to use a subliminal exposure time but can't get anything below 2 refreshes (33 ms at 800X600, 60Hz). I've been using a modified version of the new input file template ("untitled.csv"). I simply added a fixation point ("*") for 250ms followed by a "subliminal" word prime ("prime") for 15ms followed by the default "cat" and "dog" (rt:any). The log file shows a 33ms exposure time rather than the 15-17ms time I need. I've set the default style to 800x600. I've checked that my systems have a recent version of DirectX installed (9.0). I've tried specifying 15ms, 16ms, and 17ms. DirectRT clocks my refresh rate at 16.96ms or 58.96Hz. I have DirectRT version 2008.1.0.11.
I've attached the following:
DxDiag.txt
untitled.csv (the input file)
1_log.csv (the log file)
Please let me know what else I can try.
Thanks,
Norman
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