Presenting events simultaneously with delay

[pedrozuccolo]

Hello,

I have two questions:

How I can set up a trial that includes both a visual stimuli and a digital output for triggering a stimulator to administer an electrical shock in which the shock stimulus begins 3800ms after the visual stimulus is presented?

How do I know how much time I have left in my license key?

Thanks

[MonikaT]

You can accomplish this by having two events attached to one trial. The first event will be your visual stimuli set to end at 3800 ms. The second event will be the Digital Output. The stimulus will remain on the screen unless explicitly erased.

Regarding your license key question, the time will be shown on the main SuperLab window. I looked at your activity and it looks as if your time has expired today.

[pedrozuccolo]

Hi, Monika,

we have resumed this experiment this month and I am having problems presenting two events simultaneously, just like I have decribed above. I have attached two events in the same trial, the first of which will last 5700ms before the presentation of the second, which should last 200ms. During this 200ms, the first stimulus should be visible, but that is not what is happening. I have attached an experiment package so you can see how the experiment is organized.

Could you help me figure out what I am doing wrong?

Thanks

[Hisham]

You actually have more than two events in the trial:

• Show a picture
• Brief digital out signal 1
• Brief digital out signal 2
• Show a blank text that uses a variable time limit

Note that on this last event, the variable time limit can be several seconds long.

The picture does stay on screen throughout the digital output because events of type Digital Output never erase the screen. However, right after the digital output, you have a blank text event “IET_entreCSs_variavel” which erases the screen. By default, text events do erase the screen unless you change that.

I want to caution you about something else. Your trial “CS_PLUS1” is using trial pacing of 6000 ms (in the Trial Editor’s End tab), but the trial will always be longer than 6000 ms. This feature does not serve as a time limit. I suggest that you either turn it off or make sure that the trial does not last more than, say, 5900ms.

[pedrozuccolo]

Hi, Hisham,

Thank you for the reply.

In my experiment, I want to have two kinds of trials: CS_MINUS1 and CS_PLUS1. In CS_MINUS1, a visual stimulus is presented for 6s; in CS_PLUS1, another visual stimulus is presented for 6s and, but in its last 0,2s, there is an electrical stimulus that is presented simultaneously. That is why I programmed the second visual stimulus to be presented for 5,7s, followed by the digital output 2 that produces the electrical stimulation.

When comparing the durations of CS_MINUS1 and CS_PLUS1, I noticed the first trial was presented for 6s, but the second was presented for approximately 5,8s, that is why I was under the impression the visual stimulus was erased before the digital output. You are right, the picture does stay on screen during the digital output. I think I found why I am having problems. I programmed the digital output to end immediately after its presentation and that is why the screen turns black. I thought that using the trial pacing of 6s would solve the problem, but I forgot that the trial contains the inter-trial-interval (i.e., the event showing a blank text that uses a variable time limit).

I think the solution is to turn off the the trial pacing feature and program the digital output 2 to end after 0,2s after its presentation. This way I think both CS_MINUS1 and CS_PLUS1 will have the same duration.