rt and interval

[Darokh]

Hi,
I want to present a picture, which is replaced by a mask after 200 ms. After 1000 ms the next trail starts.
During this whole procedure, the person has to press one of two buttons - and I need this reactiontime.
But I am just able to set a 200 ms interval OR to get the reaction time. So the first picture is displayed and I measure the reactiontime, but the mask can´t appear.
rt:any,1000 for example in the "time" colum doesn´t work.
I know, it´s a newbie question, but I am new to this stuff :)
Kind regard,
Darokh

[jarvis24]

You could you the clear command, e.g.,

rt:any,clear200

But that would only be useful if a followup mask is not critical. That's because the clear command causes the screen to clear after 200ms (in this example) but continues to take the RT until a key is pressed.

[Darokh]

Well, but the mask has to appear, still returning the reaction time. So I can´t use the clear command I think.
It´s also not possible to have a background picture with the mask in it which appears, when I clear the screen, because there are some additional breaks in the trail where I don´t need the mask.

[jarvis24]

You could do it if you didn't need to limit the overall to 1000ms. You could also do it if you do not expect valid responses with the first 200ms window. In that case, you could simply list 200ms as the time and then take the RT to the mask.

If none of this is getting you anywhere, another possibility might be to simply have the initial stimuli and the mask as subsequent trials. You could probably get by with reducing your inter-trial interval to 10ms or so and it would appear relatively seamless. Just a thought..

The *real* answer to this, btw, is for us to add the capability to define multiple min-max values to a single trial. FWIW, that is a goal for the next version.