TTL insertaion

[jvanbavel]

I have a related problem using DirectRT 2006. I plan to show a series of 15,000ms videos. On each trial, participants will have to make a response at some point during the middle of the video. However, I want the video to play for the full 15,000ms. I am looking to have two TTLs sent for each trial. I want one TTL sent when the video starts and another TTL when participants' make their response. In other words, I want to examine the data when the video starts (i.e., stimulus locked) and when participants make a response (i.e., response locked).

Is there a work-around when the response in the video is not fixed?

[jarvis24]

First, Mickeyi--yes, you should be able to count on the ttl signal and the movie signal being sent out simultaneously at the onset of the video--i.e., with no lag due to processing/loading of the video clip.

Second, Jvanbavel, your second question regarding whether you could get a ttl signal to accompany the subject's response at some point *during* the movie can be answered, yes. Details are here:

http://www.empirisoft.com/Support/showthread.php?t=273

See in particular the sections on echoing ttl signals (revisions 2008.1.13 and 2008.1.18). Mickeyi helped us with the development of that feature so he may have some info to help you on this also if you need it.