Presenting Only Trials That Were Answered Correctly (or Incorrectly) in an Earlier Block

Summary

In “Block 1” of this experiment, we present 16 trials that require a participant response. In “Block 2”, we want to present only the trials that were answered correctly in the first block.

Design

In the experiment, we have:

• Created two responses
• Created two stimulus lists: one for even numbers and one for odd numbers
• Created two trials and two events, also for even and odd numbers
• For the events, we have set the correct response to the appropriate key for each item in the stimulus list 

The two trials are linked to “Block 1”:

Once the participant responds, we need a way to “tag” the trial as having been answered correctly or incorrectly. This is done using SuperLab’s tags feature. Tags are organized into tag sets and can be edited by choosing Tag Sets… from the Experiment menu. The requirement to tag a trial as answered correctly is common enough that SuperLab creates a default tag set:

“Block 1” and “Block 2” are linked to the same two trials. However, “Block 1” must present all of them whereas “Block 2” must present only the ones that were answered correctly earlier. We start by having all trials default to being tagged as “correct”. This is done in the Trial Editor’s Tags tab, for both the “Odd trials” and “Even trials”:

Next, we tell SuperLab to present a trial only if it is tagged as “correct”. This is done in the Trial Editor’s When to Present tab, for both the “Odd trials” and “Even trials”:

And lastly, if the participant answers incorrectly, we need to tag the trial as such. This will prevent the trial from being presented again in “Block 2”. We do this in the Event Editor’s Feedback tab, for both the “Odd numbers” and “Even numbers” events:

Closing Comments

Download the experiment and run it. The easiest way to test it is to press the ‘z’ key for all stimuli in “Block 1”. You will notice that, in “Block 2”, only half the stimuli will be presented.

If, in “Block 2”, you need to present the trials that were answered incorrectly (instead of correctly), the approach is the same. Send us an email if you are having difficulty creating that variation.

And lastly, please email us with suggestions if you think that this page can be improved in anyway.

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