Time of sketchpad and keyboard response

guipru

Hello,
Yet me...
I would like to present a stimulus during 250 ms and subject respond to this stumulus with key pressed. But I don't know how maintain the same sketchpad after 250 ms.
If I add a new sketchpad with no stimulus I must press twice the key...
Thank you for your help.
Guillaume

Josh

Hi Guillaume,

I don't understand your problem completely. Do you mean you want to present the sketchpad for 250ms, even if subjects respond quicker?

Cheers

Josh

guipru

Hi,
Not exactly. The stimulus appear 250 ms and disappear.
Subject could respond during 5000 ms (250 + 4750 ms).
But if I add a sketchpad for complete the stimulus (4750) I must press twice the key.
Sorry for the english...
Guillaume

Josh

Hi Guillaume,

Ok, the setup you need is one with the stimulus sketchpad at a duration of 0ms, followed by a keyboard item with a timeout of 250ms. After the keyboard item you place a copy of the stimulus sketchpad, with duration value 250 - [response_time]. This will make sure that the stimulus stays on for 250ms, regardless of whether a key is pressed in the meantime.

After the 2nd stimulus sketchpad you place the second screen, again with a duration of 0 ms, and followed by a keyboard item with timeout of 4750. The only problem is that you don't want to run the 2nd keyboard item if participants already pressed a key. To do this, click on the sequence item and insert the following run-if statement for the 2nd keyboard item (and also for the stimulus-off screen): run-if [response] = 'none'. (Here, response is the key logged by the previous keyboard item).

Hope this helps.

Cheers

Josh

guipru

Hi
The sequence "cratch" with my sketchap mark with : 250 - [response_time]
Argh!
But in fact the first 250ms are not the main problem.
How can I disappear my letter (cf previous post) but respond for these letters ?
Cheers
G

guipru

Finally, I just would like to present stimuli during 250ms and participant respond after without presence of stimuli. But the responses depend of these...

guipru

Actually, I use a SOA and a sketchpad with the same stimulus... but hidden (is black, like screen).