Why can I see my subliminal stimuli?

[ssmith]

We're having difficulties with display times of subliminal primes in the beta version of DirectRT 2010. The words are set to display for various times, but the words are very visible and the log files show that they are displaying for far longer than that. Updating the video drivers did not help, nor did the advice that I've found here. I had no problems with older versions of DirectRT beta...Any ideas?

[jarvis24]

Jiff128, Ssmith,

What versions of DirectRT are you using, i.e., 20xx.x.x? In cases where it worked well using a prior version, was it the same same machine? If so, what version of DirectRT was that (if you can recall)? Also, if you run some of the various samples that come with DirectRT (especially ones from the first few folders), do you get similar variance in the display times?

[ssmith]

We are currently using DirectRT 2010.122.804.10. We have run several priming studies on these same computers in the past using DirectRT 2006 (and an earlier beta version of DirectRT 2010 - last December), and the presentation times were much more precise (within 10-15 ms). The computers have 1.83GHz processors, 1GB RAM, DirectX 9, and the monitors are set to 1024x768 pixels at 85Hz.

We do get similar variance using the samples that come with DirectRT.

For instance, the sample in "4 - Applications\image priming" presents an image prime for 100ms. During a practice run the log file shows that these primes were presented for an average of 190ms instead of 100ms (SD = 44ms, ranging from 110 to 281ms).

As another example, the sample in "4 - Applications\standard priming" presents a prime word for 10ms. During a practice run, this prime was presented for an average of 114ms instead of 10ms (SD = 27ms, ranging from 49 to 159ms).

[jarvis24]

That is very unusual, I haven't heard of variance of that degree before. In your main DirectRT window, do you have an UPDATE option? If so, can you click to update your beta to the most recent version and see if the image priming sample gives you a similar pattern of data? I'll pass this on to Trevor our lead programmer who might have additional suggestions. Attaching a dxdiag.txt file could also help so we can see the details of your hardware (e.g., to figure out why v2006 could perform better on this machine).

[ssmith]

I updated the beta version so it's now 2010.124.820.10, but the timings are still too long. With the images sample, the timings run from 574-596 (instead of 500) and 125-197 (instead of 100). With my own .csv file, I'm also seeing extremely long timings (63-172, though it's set for 35). I'm not sure what a dxdiag.txt file is...

I have my program running in windowed mode, though I have some colleagues who are using the full screen and have the same problems.

Is there any way we could talk directly tomorrow afternoon to try to get this sorted out? Trevor once helped me by logging into my computer and looking at the files I was using. Is that a possibility?

[ssmith]

Here's the dxdiag.txt (I figured it out...)

[jarvis24]

SSmith,

I took a look at your dxdiag.txt file, thank you, and all seems normal. I am going to run through the same input files using the same version of the beta you are using. There is a more recent version of the package available and that may help but I will test both versions on one of our XP machines here and see if I can replicate the RT variances you are seeing. Fair to assume you did not change the resolution/style files in any way on the samples?

Blair