Adding markers from stimulus presentation software

Serial marker plugins

Markers can be created in the VU-AMS 5fs based on button presses on the device, a method mostly used in ambulatory settings or lab settings where only second-level precision is required. For synchronizing with computerized stimuli with millisecond precision, markers can be sent from the stimulus computer through the AMSi infrared cable and recorded into the VU-AMS data file.

Click the logo’s below to download the respective plugins for Presentation, OpenSesame, Authorware, Matlab, Inquisit and E-prime.

Serial marker timing test

This section explains the timing test we did to validate the timing of the serial markers one can send to the VU-AMS device.

We used an OpenSesame experiment to send out a signal via the LPT printer port (which we know exits the PC virtually instantaneous) and a serial marker to the VU-AMS device using an AMSi USB cable. Now we fed the LPT signal to the VU-AMS PCG input which is sampled at 1000Hz. The results show the serial marker appears in the VU-AMS data 1 or 2 milliseconds after the PCG signal changes (meaning the LPT printer port goes high). This means the serial markers can be used to accurately mark important moments in the VU-AMS data.