Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 13, 2023
Last Modified: January 02, 2025 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements Millisecond's version of the Wolf and Sheep Task, a visual search task used to study agency attribution. The Millisecond script is based on Lisøy (2018).
Researchers can select to run the task with an absolute screen size to ensure that distances stay the same across devices. The default setup uses proportional sizing. Go to section Defaults for more information.
Lisøy, R.S. (2018). Seeing minds: a signal detection study of agency attribution in autism and psychosis. NTNU. (Dissertation)
Lisøy RS, Biegler R, Haghish EF, Veckenstedt R, Moritz S, Pfuhl G. Seeing minds - a signal detection study of agency attribution along the autism-psychosis continuum. Cogn Neuropsychiatry. 2022 Sep;27(5):356-372. doi: 10.1080/13546805.2022.2075721. Epub 2022 May 17. PMID: 35579601.
Lisøy, R.S., Pfuhl, G., Hope, W.N & Biegler, R. Seeing Minds: A Signal Detection Study of Agency Attribution in Autism and Psychosis downloaded from: https://osf.io/preprints/osf/6yn89 License: CC-By Attribution 4.0 International
Gao, T., Newman, G. E., & Scholl, B. J. (2009). The psychophysics of chasing: A case study 603 in the perception of animacy. Cogn Psychol, 59(2), 154-179. 604 doi:10.1016/j.cogpsych.2009.03.001
10 minutes
Participants watch videos with 16 red balls (the 'wolves') and one yellow ball (the 'sheep') moving around the screen. The task is to decide whether the sheep is hunted ('stalked') by one of the wolves. If participant reply 'yes' to the question of whether 'the sheep was hunted', they are further asked to identify the hunting wolf by selecting the letter printed on the red ball that represents the 'hunting wolf'.
(1) Practice:
- 2 warm-up trials (practice trials only run 10 wolves instead of 16)
- by default, the two videos are run in fixed sequence
1. video: no wolf
2. video: wolf (letter 'L')
In this script, participants get to watch the video again if they make a mistake for either the
'agency' and the 'identification' questions during practice
(2) Test:
- 50 videos (16 wolves)
- by default, the videos are presented in a fixed sequence
- half the videos present a wolf
Trial Sequence (Test)
-> get ready (2000)
-> video (until video is done running), about 5seconds for each
-> agency question: 'was the sheep being hunted?' until response (yes or no)
-> if YES: identification question: the 16 letters are presented in a 4x4 matrix in the center of the screen
and participants can select the letter. They can change their answer until they press the 'submit' button
-> if NO: start of next trial sequence
there is no performance feedback given during test
provided by Lisøy et al (2018) under the CC-By Attribution 4.0 International License:
https://osf.io/qaeyu/
the instructions are not original to Lisøy et al (2018);
they are provided by Millisecond - can be edited under section 'Editable Instructions'
File Name: wolfandsheeptask_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| 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 |
| completed | 0 = Test was not completed 1 = Test was completed |
| propCorrectAgency | Proportion correct agency responses (out of 50 trials) |
| numberIdentityResponses | Number of YES responses to agency question (= number of identity responses) |
| propCorrectID | Proportion correct identity responses (out of numberIdentityResponses) |
| propCorrectIDTransformed | Arcsine square root transformed propCorrectID (see ) |
| meanCorrAgencyRT | Average correct agency response time (in ms) |
| meanCorrIdRT | Average correct identity response time (in ms) |
| hitRate | Hitrate (= saying 'yes' when the sheep was hunted) |
| missRate | Missrate (=saying 'no' when the sheep was hunted) - error response |
| faRate | False alarm rate (= saying 'yes' when the sheep was NOT hunted) - error response |
| crRate | Correct rejection rate (= saying 'no' when the sheep was NOT hunted) |
| zHitRate | Calculates the z-score for the hitrate. Adjustments are made if the hitrate = 0 (increased to 0.005) or 1 (decreased to 0.995)* |
| zFARate | Calculates the z-score for the false alarm rate. Adjustments are made if the FArate = 0 (increased to 0.005) or 1 (decreased to 0.995)* |
| dPrime | 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 ('wolf present') were overall distinguished from noise ('wolf absent') (d' = 0: chance performance; negative d-primes: participant treated noise as signals and signals as noise) => Lisøy et al target a d-prime around '1' to get enough false alarms for a meaningful c-value (aka avoiding ceiling/floor effects) |
| c | C-criterion in signal detection:The absolute value of c provides an indication of the strength of the subject bias (Anderson, 2015) => Response bias c in this case 'reflects the participants’ propensity to perceive the wolf as present or absent' (Lisøy et al) => negative when participant is more likely to report that signal ('wolf present') is present (propensity towards seeing agency), positive for favoring caution ('wolf absent') *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) |
File Name: wolfandsheeptask_raw*.iqdat
| Name | Description |
|---|---|
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| blockCode | Name of the current block |
| blockNum | Number of the current block |
| trialCode | Name of the current trial |
| trialNum | Number of the current trial |
| phase | "practice" vs. "test" |
| trialCounterPerBlock | TrialCounter for the current practice or test block |
| itemNumber | The itemnumber of the currently presented video |
| video | Stores the presented video |
| wolfPresent | 0 = no wolf; 1 = wolf present |
| sheepCaught | 0 = sheep is not caught by the wolf; 1 = sheep is caught by the wolf |
| actualWolf | The letter assigned to the current wolf (if any) |
Custom Dvs |
|
| agencyRsp | "yes" or "no" (response to: ) |
| selectedID | The selected letter ID of the wolf |
| agencyAcc | 1 = agency response was correct (answer to question "is the sheep being hunted?") 0 = agency response was incorrect |
| agencyRT | Latency (in ms) of agency response; measured from onset of question "is the sheep being hunted?" |
| idAcc | 1 = wolf identity was correctly identified (only relevant if participant chose 'yes' for agency response) 0 = wolf was not correctly identified |
| idRT | Latency (in ms) of identity response (measure from onset of question until 'submit' button is selected) |
Built-In Dvs |
|
| response | The response of participant for the current trial |
| correct | Correctness of response (1 = correct, 0 = error) |
| latency | Response latency (in ms) !!! the final trial data is recorded by trial.end |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Color Parameter |
||
| canvasColor | Display color of the actively used portion of the screen (the 'canvas') if set to a color other than the screenColor, the active canvas appears 'anchored' on the screen regardless of monitor size | black |
| screenColor | Color of the screen not used by the canvas ('inactive screen') | black |
| defaultTextColor | Default color of text items presented on active canvas | white |
| videoSize | The proportional size of the video relative to active canvas by default: covers the entire active canvas | 100% |
Timing Parameters |
||
| getReadyDuration | Duration (in ms) of the get ready trials | 2000 |
| feedbackDuration | Duration (in ms) of the practice feedback stims | 1000 |