Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Credits:
Millisecond thanks Dr. Susanne Jaeggi for kindly providing original instruction materials, stimuli,
as well as assistance!
as well as assistance!
Created: March 01, 2012
Last Modified: July 17, 2026 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements a basic shape n-back procedure. The n-back task is a go/nogo working-memory performance task with increasing levels of difficulty and provides two explicit response keys for the go and the nogo trials, respectively.
The implemented procedure is based on Jaeggi et al (2010).
Jaeggi, Susanne M.; Studer-Luethi, Barbara; Buschkuehl, Martin; Su, Yi-Fen; Jonides, John; Perrig, Walter J. (2010). The relationship between n-back performance and matrix reasoning - implications for training and transfer. Intelligence, 38, 625–635.
Adjustments to z-scores as recommended by: Gregg, A. & Sedikides, C. (2010). Narcissistic Fragility: Rethinking Its Links to Explicit and Implicit Self-esteem, Self and Identity, 9:2, 142-161 (p.148)
15 minutes
In the 1-key single n-back task, participants are shown a sequence of stimuli (here: a sequence of yellow shapes on a black background) and are asked to indicate whether the currently presented stimulus fulfills the following criteria:
For N=0 trials: - is the shape the same as the shape '1.gif'? If so (it's a target), and press "A". If not, press the "L" key.
For N=1 trials: - is the shape the same as the one that preceded it? If so (it's a target), and press "A". If not, press the "L" key.
For N=2 trials: - is the shape the same as the one presented two trials before? If so (it's a target), and press "A". If not, press the "L" key.
For N=3 trials: - is the shape the same as the one presented three trials before? If so (it's a target), and press "A". If not, press the "L" key.
Etc. for increasing levels of N
provided by Millisecond - can be edited under section Editable Instructions
in script 'singlenbacktask_shapes_2keys_instruct_inc.iqjs'
File Name: singlenbacktask_shapes_2_keys_summary*.iqdat
| Name | Description |
|---|---|
| startDate | Date the session was run |
| startTime | Time the session was run |
| subjectId | Participant ID |
| groupId | Group number |
| sessionId | Session number |
| elapsedTime | Session duration in ms |
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| completed | 0 = Test was not completed 1 = Test was completed |
| round | The total number of experimental blocks run |
| propCorrect | Overall proportion correct (across all test blocks) |
| targetTrialCountOverall | The overall count of target trials runs (across all levels of N) |
| nrRateTargetOverall | The overall proportion of No Response target trials (across all levels of N) |
| hitRateOverall | Overall hit rate (across all levels of N) |
| hitRTOverall | Mean response time (in ms) of correctly responding to target trials (across all levels of N) |
| errorRTTargetOverall | Mean response time (in ms) of pressing the incorrect response key to targets (across all levels of N) |
| nontargetTrialCountOverall | The overall count of nontarget trials runs (across all levels of N) |
| nrRateNontargetOverall | The overall proportion of No Response nontarget trials (across all levels of N) |
| faRateOverall | Overall False Alarm/Commission Error Rate (across all levels of N) |
| faRTOverall | Mean response time (in ms) of pressing incorrect response key for nontarget trials (across all levels of N) |
| corrRTNontargetOverall | Mean response time (in ms) of pressing correct response key for nontarget trials (across all levels of N) |
| zHitRateOverall | The z-score of the overall hit rate |
| zFaRateOverall | The z-score of the overall False Alarm rate |
| dPrimeOverall | Computes d' (parametric measure of sensitivity) The higher the value, the better targets were overall correctly distinguished from nontargets (d' = 0: chance performance; negative values: nontargets were treated as targets and targets were treated as nontargets) |
| cOverall | C-criterion in signal detection:The absolute value of c provides an indication of the strength of the response bias/response style negative: participant more likely to report that signal (go stims) is present (liberal response style) may favor faster responding in speed-accuracy trade-off response paradigms positive: favoring caution (conservative response style) |
Level N Summary Statistics (Explained Only For Level N=0) |
|
| targetTrialCountN0 | The count of target trials runs in N0 trials |
| nrRateTargetN0 | The proportion of No Response target trials in N0 trials |
| hitRateN0 | Hit rate in N0 trials |
| hitRTN0 | Mean response time (in ms) of correctly responding to target trials in N0 trials |
| errorRTTargetN0 | Mean response time (in ms) of pressing the incorrect response key to targets in N0 trials |
| nontargetTrialCountN0 | The count of nontarget trials runs in N0 trials |
| nrRateNontargetN0 | The proportion of No Response nontarget trials in N0 trials |
| faRateN0 | False Alarm/Commission Error Rate in N0 trials |
| faRTN0 | Mean response time (in ms) of pressing incorrect response key for nontarget trials in N0 trials |
| corrRTNontargetN0 | Mean response time (in ms) of pressing correct response key for nontarget trials in N0 trials |
Signal Detection Metrics |
|
| zHitRateN0 | The z-score of the hit rate in N0 trials |
| zFaRateN0 | The z-score of the False Alarm rate in N0 trials |
| dPrimeN0 | Computes d' (parametric measure of sensitivity) for N0 condition |
| cN0 | C-criterium in 0back condition |
File Name: singlenbacktask_shapes_2keys_raw.iqdat
| Name | Description |
|---|---|
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| blockcode | The name the current block (built-in Inquisit variable) |
| blocknum | The number of the current block (built-in Inquisit variable) |
| trialcode | The name of the currently recorded trial (built-in Inquisit variable) |
| trialnum | The number of the currently recorded trial (built-in Inquisit variable) trialnum is a built-in Inquisit variable; it counts all trials run even those that do not store data to the data file. |
| totalBlocks | The total number of experimental blocks run |
| n | The current level N tested |
| startTrialCounter | Keeps track of how many start trials have been run |
| stimulusItem.1 | The shape presented |
| stimulusNumber.1 | The item number of the presented shape |
| currentTarget | The item number of the current target |
| response | The Response of the participant (scancode of response button) 0 = no response 31 = 'A' key (target key) 38 = 'L' key (non-target key) (57 = spacebar) |
| responseCategory | "Correct", "Incorrect", "No Response" |
| correct | The correctness of the response (1 = correct; 0 = otherwise) |
| latency | How fast a participant responded within the given timeframe, if at all (in ms) no responses = the entire trialduration |
| list.blockAcc.mean | Proportion correct during the current block (start trials are excluded from block acc assessment by default, editable) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Design |
||
| allowPracticeRepeat | True: practice can be repeated as often as indicated (default) false: practice cannot be repeated | true |
| excludeStartTrialfromPerformanceMeasure | True (1): performance during start trials that cannot be targets yet is not considered for Block level performance analyses, e.g. for feedback purposes false (0): performance during start trials that cannot be targets yet IS considered for block performance analyses | true |
Timing Parameters |
||
| soa | Stimulus Onset Asynchrony | 3000 |
| stimulusPresentationTime | The presentation time (in ms) of the stimuli | 500 |
Debugging |
||
| debugmode | Debugmode = 1: targetalerts are shown on screen, debugmode = 0, no targetalerts are shown | 0 |