FocusOn announcement before each stimuli

[abringas]

Hi, I'm new to BCI2000 and I have some issues trying to do the next thing:

Using StimulousPresentation, I did one sequence of 4 stimuli and I want before each stimuli to display a FocusOn announcement for just a second to warn that the stimuli is going to appear next.

I've tried changing the application parameters, but the only thing I've achieved is to display the FocusOn announcement before the sequence.

Thanks in advance,

[mellinger]

Hi,

I'm not sure whether I understand what you are trying to do.

The purpose of a "FocusOn" announcement is to instruct the subject before presentation begins. Then, during presentation, all stimuli are treated equally, because otherwise information about the desired stimulus would be physically present in stimulation itself, which would defeat the idea of an ERP/P300 experiment.

If, for some special reason, you actually want to do it that way, define your hint as an additional stimulus, and specify a "deterministic" sequence containing that stimulus at the intended places. To achieve long pseudo-random sequences that way, you can use a program such as Octave or Matlab to produce the sequence, and then copy-and-paste it into the Sequence parameter, or write it to a file in the text-based BCI2000 parameter format, and load it into BCI2000 manually or by script commands.

Regards,
Juergen

[abringas]

Hi Juergen,

thank you so much for your answer! I will try to do a pseudo-random sequence with Matlab.

Regards,