I want to do an adaptive N-back task of 20 stimuli, it has 14 non-targets (70%) and 6 targets (30%), in order for them to end up with an N-back level that is doable for them but can still improve on (60 - 75% accuracy). When people have an accuracy higher than 75%, they will increase in N-back level (1-back, 2-back, 3-back, 4-back), when the accuracy is 60% of lower they will decrease in level.
The problem is now that when people press the non-target button, they will have an accuracy of 70%, meaning they will not decrease in N-back level (while they should).
I was wondering if it would be good to change the ratio targets/non-targets to 50/50? I ask this because I normally see ratio's of approximately 30/70.
Thank you for your feedback!
Hi the target to non-target ratio in an adaptive N-back task is a delicate balance. Your concern is valid: with a 70% non-target and 30% target ratio, participants might maintain or even advance their N-back level by predominantly pressing the non-target button, potentially skewing the accuracy measure.
Moving to a 50/50 ratio could address this issue in several ways:
Reduced Bias for Non-Target Responses
Increased Challenge
Better Assessment of Working Memory
Avoids Over-Simplification
Alignment with Task Objectives
Thanks a lot for your reply!
What exactly do you mean with "avoids over-simplification"?
Alternatively to changing the ratio to 50/50, I could change my thresholds for increasing and decreasing a level in the N-back from 60-75% to 70-80%.
What do you think would be the better option?
Hi,
Avoids Over-Simplification: With a skewed ratio, there's a risk that participants might find a simple heuristic to 'game' the system. A balanced ratio avoids this.
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