[miksk]

Dear SuperLab community,

I am developing a numerical discrimination task in SuperLab 4.5, in which participants are presented with a set of Arabic numerals and are instructed to determine the numerically larger option during a paired presentation. For each block, SuperLab retrieves 14 events from predefined stimulus lists and randomizes the order for each participant. The experiment works as planned, with 14 stimulus presentations and response screens per block, but the output file randomly contains multiple instances of the same stimulus with different response times, e.g:

Originally Posted by SuperLab Output

3 Block1 Arabic1, 1 ArabicResp1 (1, 1 6) (based on code value) NR 0
3 Block1 Arabic1, 2 ArabicResp1 (2, 4 8) J j Pressed (based on code value) C 730
3 Block1 Arabic1, 3 ArabicResp1 (3, 7 3) F f Pressed (based on code value) C 235
3 Block1 Arabic1, 3 ArabicResp1 (3, 7 3) F f Pressed (based on code value) C 1268
3 Block1 Arabic1, 4 ArabicResp1 (4, 5 1) F f Pressed (based on code value) C 308

However, these stimuli are in fact not presented twice in a row during the experiment, but are nevertheless stored as multiple instances (with varying RT measures) in the output file. This also happens at seemingly random frequencies across blocks and participants (i.e. where some participant outputs consistently detail 14 events for a block, whereas others have multiples ranging from 14-21 events). Since there appears to be no structure to when and for whom this happens, this leads me to believe that the fault lies with a SuperLab bug rather than the experimental setup.

For instance, the same five trials for participant 1 do not show this behavior:

Originally Posted by SuperLab Output

1 Block1 Arabic1, 1 ArabicResp1 (1, 1 6) (based on code value) NR 0
1 Block1 Arabic1, 2 ArabicResp1 (2, 4 8) J j Pressed (based on code value) C 960
1 Block1 Arabic1, 3 ArabicResp1 (3, 7 3) (based on code value) NR 0
1 Block1 Arabic1, 4 ArabicResp1 (4, 5 1) F f Pressed (based on code value) C 749
1 Block1 Arabic1, 5 ArabicResp1 (5, 7 2) F f Pressed (based on code value) C 586

Has anyone here experienced something like this before, and if so, what could be done to amend the error? I could, of course, manually delete multiples after testing, but it would make my life easier if this did not happen at all.

I am running SuperLab version 4.5.4 on a 12" Macbook (early 2015), using MacOS Sierra 10.12.3.

Thank you for your time and help!

[Arman]

Do you mind attaching your experiment package (via File > Create an Experiment Package...)?