N Back Task Min/Max Values


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AnthonyFCollinsSussex
AnthonyFCollinsSussex
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Hi there!

Hope all is well. I am posting here after much much struggle. I am using the N-back Task for one of my PhD online experiments. I need to know the minimum and maximum possible score of the N-back task script attached (taken from the Inquisit Library). I have also attached a raw excel data file of myself completing the entire task in order to observe how the N-back DV behaves (DV being accuracy rate). I know it is possible to compute the minimum/maximum values of the DV based on key variables such as correct rejections, false alarms etc, I have tried very hard to work this out... but arrive at different values each time! I need to know this information to generate my predictions/statistical model I am using in a pre-reg document. I could seriously do with some help on this.

Many Thanks in advance.

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NBACK.iqx (98 views, 36.00 KB)
Dave
Dave
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AnthonyFCollinsSussex - 1/10/2022
Hi there!

Hope all is well. I am posting here after much much struggle. I am using the N-back Task for one of my PhD online experiments. I need to know the minimum and maximum possible score of the N-back task script attached (taken from the Inquisit Library). I have also attached a raw excel data file of myself completing the entire task in order to observe how the N-back DV behaves (DV being accuracy rate). I know it is possible to compute the minimum/maximum values of the DV based on key variables such as correct rejections, false alarms etc, I have tried very hard to work this out... but arrive at different values each time! I need to know this information to generate my predictions/statistical model I am using in a pre-reg document. I could seriously do with some help on this.

Many Thanks in advance.

The computation of the DV is very straightforward, so I'm not sure where the problem is.

values.DV = (values.TotalHits - values.TotalFA)/values.TotalBlocks

where
- values.TotalHits is the number of hits across all experimental blocks,
- values.TotalFA is the number of false alarms across all experimental blocks, and
- values.TotalBlocks is the number of experimental blocks run.

Hits can only occur in target trials. You have 5 target trials per experimental block, so max. 5 hits per experimental block, min. obviously 0.
False alarms can only occur in non-target trials. You have 10 non-target trials per experimental block, so worst case is 10 false alarms per block, best case is 0.

You run 12 experimental blocks, i.e. a total of 60 target trials and a total of 120 non-target trials. Best case is all hits & no false alarms, so

DV = (60 - 0) / 12 = 5

Worst case is no hits & all false alarms, so

DV = (0 - 120) / 12 = -10


Edited 5 Months Ago by Dave
AnthonyFCollinsSussex
AnthonyFCollinsSussex
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Dave - 1/10/2022
AnthonyFCollinsSussex - 1/10/2022
Hi there!

Hope all is well. I am posting here after much much struggle. I am using the N-back Task for one of my PhD online experiments. I need to know the minimum and maximum possible score of the N-back task script attached (taken from the Inquisit Library). I have also attached a raw excel data file of myself completing the entire task in order to observe how the N-back DV behaves (DV being accuracy rate). I know it is possible to compute the minimum/maximum values of the DV based on key variables such as correct rejections, false alarms etc, I have tried very hard to work this out... but arrive at different values each time! I need to know this information to generate my predictions/statistical model I am using in a pre-reg document. I could seriously do with some help on this.

Many Thanks in advance.

The computation of the DV is very straightforward, so I'm not sure where the problem is.

values.DV = (values.TotalHits - values.TotalFA)/values.TotalBlocks

where
- values.TotalHits is the number of hits across all experimental blocks,
- values.TotalFA is the number of false alarms across all experimental blocks, and
- values.TotalBlocks is the number of experimental blocks run,

Hits can only occur in target trials. You have 5 target trials per experimental block, so max. 5 hits per experimental block, min. obviously 0.
False alarms can only occur in non-target trials. You have 10 non-target trials per experimental block, so worst case is 10 false alarms per block, best case is 0.

You run 12 experimental blocks, i.e. a total of 60 target trials and a total of 120 non-target trials. Best case is all hits & no false alarms, so

DV = (60 - 0) / 12 = 5

Worst case is no hits & all false alarms, so

DV = (0 - 120) / 12 = -10


Hi Dave

Thank you so much for this, on this occasion my basic math failed me! I was focusing too much on how the DV was changing to the decimal point in the output and it threw my basic calculations somewhat, per usual over-complicating things.

I very much appreciate that.

Yours Sincerely

GO

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