Millisecond Forums

Dear Community,

I have a design where people are repeatedly presented with faces and they have to indicate the emotion the face displays. An example block looks like this:

<block SadAngry>
/ trials = [1 = practice; 2 = Keys_SadAngry; 3-100 = noreplace(Mask_Sad_l, NoMask_Sad_l, Mask_Angry_r, NoMask_Angry_r)]
/ onblockbegin = [values.reminder_left = "Sad"; values.reminder_right = "Angry"]
</block>

Now, I would like to have single trial per block that is an attention check. This attention check should be somewhere mixed in the 3-100 experimental trials. Mask_Sad_l and so forth draw without replacement from a pool of items. If I try to add it like this: 3-101 = noreplace(Mask_Sad_l, NoMask_Sad_l, Mask_Angry_r, NoMask_Angry_r, AttentionCheck), I get multiple attention checks per block. How can I implement it that I only have one check per block?

Best,

Max