Stimulus presentation: timing and synchronization

1

Dear experts,

I am trying to program an experiment in SuperLab in which 20 emotional images are presented twice with superimposed digits that can be congruent or incongruent (example attached).

I was able to create the image and digit lists successfully. However, I am having difficulty presenting the stimuli simultaneously within the same trial.

The intended trial structure is:

  • Image + digits presented simultaneously for 500 ms

  • Followed by the same image + fixation cross presented simultaneously for 3500 ms

At the moment, SuperLab presents the events sequentially as:
image → digits → image → fixation cross

instead of overlaying them simultaneously.

Additional requirements:

  • Responses should be made only to the digits (the images are distractors)

  • The trial duration should remain fixed even if the participant responds early

  • Reaction time should be measured relative to the onset of the digits

Could someone please advise on the correct way to configure simultaneous visual stimuli and timing for this paradigm in SuperLab?

I attach the experiment file and an illustration of the intended task structure.

Thank you very much in advance.

Best regards,
Jose Teles
on behalf of HEI-Lab, Lusófona University

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2

Dear experts

I was able to solve the issue of presenting the image + digits and image + fixation cross simultaneously.

I now have a follow-up question regarding response recording and accuracy.

In my task, participants respond to the digits according to parity:

  • both digits even or both digits odd = “same”

  • one even and one odd = “different”

The correct responses are defined in the digits event, and the RT timer is reset at digit onset. However, participants can still respond during the subsequent fixation event, after the digits have disappeared.

How can I make sure that responses given during the fixation interval are still evaluated according to the correct response defined in the previous digits event?

Ideally, I would like the output to contain a single accuracy variable/column coded as:

  • 1 = correct

  • 0 = incorrect

regardless of whether the participant responded during the digits event or during the fixation event.

What is the best way to configure this in SuperLab?

Thank you very much in advance.

3

What you are asking for is easily done in the new SuperLab 7.

In SuperLab 6, there is a workaround. Can I suggest a Zoom call to do screen sharing? please send me an email.