Introduction
| This is a touchscreen and mouse friendly version of the Simon task. |
The N-Back task goes back more than half a century, developed in the 1950s by Kirchner, as you can read in more detail on wikipedia.
In short, in the N-Back task, participants are presented a sequence of stimuli one-by-one. For each stimulus, they need to decide if the current stimulus is the same as the one presented N trials ago. The N can be 1 trials, 2 trials, 3 trials, etc. The higher the number, the more difficult the task. The factors that seem to influence the performance are not only the N, but also the speed of presentation and the size of the set of stimuli.
About this implementation
Key features of this implementation:
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This is a 2-back task
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The total stimulus set contains 15 stimuli (letters)
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Each stimulus is presented for maximally 760 milliseconds
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The intertrial interval is 2000 ms
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A new stimulus is presented every 2760 milliseconds
The letters A,B,C,D,E,H,I,K,L,M,O,P,R,S, and T are being used.
There are 25 trials in each of the three blocks.
| In this n-back task, the first training block shows the previous two stimuli, which helps the participant to learn the task. |
Run the demo
| You need the mouse and sound |
Data output file
| In PsyToolkit, the data output file is simply a textfile. The save line of the PsyToolkit experiment script determines what is being saved in the data output file. Typically, for each experimental trial, you would have exactly one line in your text file, and each number/word on that line gives you the information you need for your data analysis, such as the condition, response speed, and whether an error was made. |
Meaning of the columns in the output datafile. You need this information for your data analysis.
| Colum | Meaning |
|---|---|
1 |
BLOCKNUMBER |
2 |
trial counter |
3 |
the score of current trial (1=correct,0=wrong) |
4 |
whether the response given was a correct match (1=participant correctly matched 2-back trial) |
5 |
whether the response given was a miss (1=participant failed to respond) |
6 |
whether the response given was a false alarm (1=participant clicked even though it was a non-match) |
7 |
reaction time in milliseconds |
8 |
computer determined this to be a matching trial (1: match, except for first two trials) |
9 |
current stimulus number (between 1 and 15) |
10 |
stimulus previous trial (n-1) |
11 |
stimulus two trials ago (n-2) |
Download
| If you have a PsyToolkit account, you can upload the zipfile directly to your PsyToolkit account. Watch a video on how to do that. If you want to upload the zipfile into your PsyToolkit account, make sure the file is not automatically uncompressed (some browsers, especially Mac Safari, by default uncompress zip files). Read here how to easily deal with this. |
Further reading
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Kirchner, W. K. (1958). Age differences in short-term retention of rapidly changing information. Journal of Experimental Psychology, 55, 352-358.
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Jaeggi, S.M., Buschkuehl, M., Perrig, W.J., & Meier, B. (2010). The concurrent validity of the N-back task as a working memory measure. Memory, 18, , 394–412.