Configuration of event markers in a study with SuperLab 6, EEG (Actichamp) and StimTrackerDuo


Our research group is going to conduct their first experiment combining SuperLab and EEG, so if the question is a little dumb we apologize in advance.

First, what we have is: a PC tower conducting a task in SuperLab v.6; StimTrackerDuo (Cedrus), Actichamp for EEG (Brain Products), and a laptop connected with the Actichamp to record EEG.

What we want: To create event markers which identify what stimuli were presented; and event markers that show if the participant response was correct or incorrect (sorry quick question about this, the task is like go-nogo, so we assigned a letter of the PC keyboard to response, but we also have the cedrus keyboard. It is better to use cedrus keyboard? Thanks).

Our doubt: How do we connect all the devices? Our first idea is: to connect via USB the PC tower with the StimTrackerDuo; connect the StimTrackerDuo via m-pod (below is the link of this product) to the Actichamp; and finally connect the Actichamp with the laptop.

Is good this configuration or there is another alternative? Because we do not have the m-pod for Actichamp, so if we can avoid buying it that would be nice. What we want is to have marks of the type of stimuli presented and participants’ responses (good or bad) in the EEG recorder.

Another doubt that we have is, if the first configuration is the best way, in SuperLab → Stimulus → Digital Output, what do we have to choose in device? USB, StimtrackerDuo or c-pod for Actichamp?

Thank you very much! m-pod for BP actiCHamp – Cedrus

I don’t see how you can implement what you are describing without an m-pod for actiCHamp. You will need that.

You also mentioned that you have a Cedrus keyboard. Did you mean a response pad? e.g. RB-740 or RB-540? if you have one and it’s the current RB-x40 generation, you also need this DisplayPort cable. This way, StimTracker can automatically mark key presses.

We have a new version 6.3 of SuperLab due out in a couple of weeks. The only new features and updates in this release are related to sending… event markers! I’m pretty sure you will like it. Also, in 6.3, you won’t need to choose a device; SuperLab will look for it automatically.

Wow what a coincidence!! We are looking for that update definitely.

Thanks for your quick response. Indeed, we have the Cedrus Keyboard. However, today and tomorrow is holiday in our city so I cannot specify what model is. On Monday I will write you. But is different if the participant use the Cedrus keyboard instead of, for example, press M in the keyboard? I mean, for event markers, is better to use Cedrus?

And finally, just to be sure, the connection would be: PC with SuperLab is connected via USB to the StimTracker, Stimtracker connected with Actichamp via m-pod specific for Actichamp, Actichamp connected to the laptop with the EEG recording software, right?

Thanks again!

There is a difference in timing precision. It is due to the USB driver that’s on the computer.

  • With a keyboard, precision is about 10 to 12ms.

  • With a Cedrus response pad in keyboard mode, precision is the same as a computer keyboard: 10 to 12ms.

  • With a Cedrus response pad in standard mode (also called XID mode), timing precision is about 5-6ms for responses. For sending out event markers, it’s only a 2ms delay with zero jitter.

The other advantage of the response pad is that you can connect it directly to StimTracker. This means that on actiCHamp, the keypress event markers will have sub millisecond precision because it is all done in hardware.

For the connections:

  • The response pad will be connected to the SuperLab PC via USB and to StimTracker via a DisplayPort cable.

  • StimTracker will be connected to the SuperLab PC as well via USB and to m-pod. m-pod plugs into actiCHamp directly which would be connected to a different laptop.

We recommend against using a single laptop for stimulus presentation and for EEG data collection.

Hello Hisham,

Thanks for your explanation, we will try to use the response pad instead of the PC keyboard.

I confirm that our response pad is RB-840, and we have the Display port cable that you have mentioned. So, the only thing that we need is the m-pod to connect the StimTracker to Actichamp, right? m-pod for BP actiCHamp – Cedrus

Correct. On the Duo, you cannot get TTL output without an m-pod. On the Quad model, there is a direct TTL output but it requires a custom cable and is not as flexible as m-pod output.