I'm brand new on this forum (will help other people if able to at some points). I'm writing because I'm facing the following difficulty while programming a dual-task (PRP-like) trial.

Suppose S1 is a visual stimulus, S2 an auditory stimulus.  S1 and S2 require distinct manual keypresses (right hand and left hand).

The visual S1 remains on the screen for 2,500 ms or until a keypress is sensed.

An important point is that the onsets of S1 and S2 are separated by a duration of one refresh cycle, that is about 14 ms (on my computer).

I can set the duration of the visual S1 to 5 ms, selected the No clear after, with a time limit to respond set on 2500 ms, and with the end action set on none

In doing so, the SOA between S1 and S2 will be of 14 ms, S1 will remain on the screen for 2500 ms and one can answer to S1 BUT S1 won't disappear !

Now, if the end action is set on Terminate, then the experiment and timing are affected.

In other words, how is it possible to present a visual stimuli and allowing an answer that will suppress the display of this stimulus while other events (objects) are underway ?

Best
François Maquestiaux

Please have a look at this post from Brandon http://support.pstnet.com/forum/FindPost233.aspx

It explains a method that should overcome your problem.

Thanks

Anthony McGuffie