Last Modified: January 19, 2026 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements the Continuous Performance Test AX (CPT-AX, Rosvold et al, 1956), a test of sustained and selective attention. This script implements the short version of the task (child version).
Rosvold, H.E., Mirsky, A., Sarason, M., Bransome, E.D., Jr., and Beck, L.H. A Continuous Performance Test of brain damage. Journal of Consulting Psychology, 20, 343 (1956).
Gregg, A. & Sedikides, C. (2010). Narcissistic Fragility: Rethinking Its Links to Explicit and Implicit Self-esteem, Self and Identity, 9:2, 142-161
5 minutes
Participants get presented a sequence of letters (one-by-one). Task: press the Spacebar whenever the letter is an X that follows an A.
phase "AX"
- 2 blocks practice
- 10 (short version) test blocks
- each block runs 31 letters with: 6 targets (target = letter X that follows an A) ~ 5min total for short version)
- the no-target letters are selected randomly WITH replacement from item.axLetters (with the constraint that no A is followed by an X)
in this script, any letter can precede an X (including X itself); any letter can follow an A (including A itself);
the number of 'no-signal As' as well as 'no target Xs' are randomly determined per block
Trial Sequence:
letter (690ms)-> ISI: blank screen (230ms)-> letter....
response is accepted until end of letter duration
(trial timings can be edited under section Editable Parameters)
see script cpt_ax_short_instructions_inc.iqjs
File Name: cpt_ax_short_summary*.iqdat
| Name | Description |
|---|---|
| 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 |
| startdate | Date script was run |
| starttime | Time script was started |
| subjectid | Assigned subject id number |
| groupid | Assigned group id number |
| sessionid | Assigned session id number |
| elapsedtime | Time it took to run script (in ms); measured from onset to offset of script |
| completed | 0 = Test was not completed 1 = Test was completed |
| blockCountAXPractice | Counts the number of practice blocks run for phase AX |
| blockCountAXTest | Counts the number of test blocks run for phase AX |
| axTestSignalTrialCount | Counts all signal (=target) trials during phase AX |
| axTestMissCount | Number of errors when X was presented but no response was given during phase AX |
| axTestMissRate | Omission rate during phase AX |
| axTestHitRate | Hit rate during phase AX |
| axTestNoiseTrialCount | Counts all non-signal (= non target) trials during phase AX |
| axTestFalseAlarmCount | Number of false alarms during phase AX |
| axTestFalseAlarmRate | Commission rate during phase AX |
| axTestCorrRejectRate | Correct rejection rate during phase AX |
| zHitRateAXTest | The calculate z-score of the hitRate during phase AX |
| zFARateAXTest | The calculated z-score of the falseAlarm/commission rate during phase AX |
| dPrimeAXTest | Computes d' (parametric measure of discriminability btw. signals and noise) => Range (in this script) -5.1516586840152740479 <= dprime <= 5.1516586840152740479 (=perfect performance) => The higher the value, the better signals (go stims) were overall distinguished from noise (nogo stims) (d' = 0: chance performance; negative d-primes: participant treated nontargets as targets and targets as nontargets) |
| cAXTest | 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 is present (liberal response style) may favor faster responding in speed-accuracy trade-off response paradigms positive: favoring caution (conservative response style) |
File Name: cpt_ax_short_raw*.iqdat
| Name | Description |
|---|---|
| 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 |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| 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. |
| phase | Current phase of the procedure: "ax practice" vs. "ax test" |
| blockCountAXPractice | Counts the number of practice blocks run for phase AX |
| blockCountAXTest | Counts the number of test blocks run for phase AX |
| previousLetter | The letter presented in the previous trial |
| currentLetter | The letter presented in the current trial |
| response | The scancode for the key that was pressed (if any) 57 = spacebar press 0 = noResponse |
| correct | Whether the response was correct: 1 = correct; 0 = error |
| latency | The response time in milliseconds; measured from onset of letter |
| stimOnsetTimestamp | The onsettime of each letter (measured from onsettime of script) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Sizing Parameters |
||
| letterHeight | The size (proportional to canvas height) of the the letters | 8% |
Timing Parameters |
||
| letterDuration | Duration of the letters in ms (time to respond) | 690 |
| isi | Interstimulus interval (= blank screen) in ms | 230 |