I have looked through the forum and the articles in which Superlab
appears, and I can’t found the solution for my questions. I would like to
conduct an experiment with subliminal priming, in which stimulus
presentation takes only 15ms. Then I present a mask, next a word and
finally I make a question, collecting reaction time in response.
I would like to know if Superlab enables this requirement, and about the
accuracy in record reaction times (I had read in the forum something
about 10-12 ms).
I will be very grateful to you if you could help me.
I am looking forward to hearing about your news.
Sincerely.
It is important to realize that you cannot specify and obtain a stimulus presentation time of 15 ms. The presentation time will always be a multiple of the refresh time of your monitor + video card. For example, if your monitor has a 60 Hz refresh rate, this means that the refresh time is 1/60th of a second and an image can be drawn (or erased) only 16.6, 33.3, 49.9 ms, and so forth.
When presenting stimuli, SuperLab 4.0 synchronizes with the refresh rate of the screen. To have your stimulus appear for one refresh time, set the time limit on your event to just 1 ms. This way, SuperLab will round up the time to the next refresh time.
As for reaction time accuracy, 10-12 ms is about right when using a USB keyboard on Windows (slightly less on Mac OS).
I’m running Superlab 4.0.8 on a 2009 iMac (OS 10.5.8), and I can’t seem to make my prime quite subliminal enough. I have a fixation cross (500ms), then a delay (500ms), then a prime (1 ms), then a mask (500ms), but I can still see the prime before the mask. Do I play around with what happens before stimulus presentation (e.g., erase screen), or something? Thanks.