Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Millisecond thanks Sarah Reeve for assistance with this script!
Created: January 28, 2014
Last Modified: January 27, 2023 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements the Jumping to Conclusion (JTC) Beads Test, a probabilistic reasoning task.
The implemented procedure is similar to the one described in:
Garety, P. A., Hemsley, D. R. & Wessely, S. (1991). Reasoning in deluded schizophrenic and paranoid patients : Biases in performance on a probabilistic inference task. Journal of Nervous and Mental Disease, 179, 194-201.
1 minute
Participants are presented with 2 jars (A and B) with different ratios of red to blue beads (e.g. 15:85). They are told that the computer selects one jar and draws beads from it with replacement. The computer will draw one bead at a time and always returns the bead to the jar before it draws the next bead. The participant's task is decide which jar the computer selected. By default, participants can ask for as many beads as they need to make a decision (number of max. drawings can be limited). A sequence of small red and blue beads at the bottom of the screen reminds participants of all the beads drawn up to this point.
This script includes the code to run more than one trial. By default, only 1 trial is run.
The default design of this JTC task is consistent with the "draws to decision" methologies:
Participants can request as many beads as they need to make a decision.
!HOWEVER, the number of drawings can be limited via an editable parameter (parameters.max_drawings).
Go to section Editable Parameters and edit parameters.max_drawings.
Bead Sequence: the default bead sequence is randomly determined (with replacement).
If a predetermined sequence is needed, go to
a) section Editable Parameters and edit parameters.type_drawing accordingly
b) section Editable Lists and edit the drawing sequence under list.beadsequence_predetermined accordingly
Feedback is optional. By default, participants receive feedback at the end.
To change: Go to section Editable Parameters and edit parameters.feedback
This script randomly selects the targetjar per trial.
By default, this script only runs 1 trial but further trials can be added.
Go to section 'Editable Parameters' for more information
Jar images: the default images with this script contain 100 beads in each jar
Example: 85 of one color, 15 of the other.
(go to Editable Stimuli to change the images).
The provided instructions are provided by Millisecond and can be edited under
section Editable instructions.
File Name: jtc_beadtask_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 |
| typeDrawing | "random" vs. "predetermined" (can be set under section Editable Parameters) |
| maxDrawings | "unlimited" vs. an integer (can be set under section Editable Parameters) |
| feedback | True (1) = participants receive feedback at the end false (0) = participants receive no feedback at the end (can be set under section Editable Parameters) |
| numberOfTrials | The number of trials run |
| propCorrect | Proportion correctly selected jars |
| meanBeadCount | The mean bead count across trials |
| meanrtDrawing | Mean latency (in ms) of trial.beaddrawing |
| medianrtDrawing | Median latency (in ms) of trial.beaddrawing |
File Name: jtc_beadtask_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, group, | With the current subject/groupnumber |
| 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 |
| typeDrawing | "random" vs. "predetermined" (can be set under section Editable Parameters) |
| maxDrawings | "unlimited" vs. an integer (can be set under section Editable Parameters) |
| feedback | True (1) = participants receive feedback at the end false (0) = participants receive no feedback at the end (can be set under section Editable Parameters) |
| trialCounter | Number of trials run |
| jarABalls, | Stores the ratio of red to blue beads in jar A (default: "85R:15B") |
| jarBBalls, | Stores the ratio of red to blue beads in jar B (default: "15R:85B") |
| biggerP | The probability of the colored beads with the larger amount |
| targetJar | "A" or "B" (counterbalanced by groupnumber) |
| bead, | 1 = high probability bead drawn 2 = low probability bead drawn |
| stimulusItem | The presented stimuli in order of trial presentation |
| response | The participant's response |
| latency | The response latency (in ms); measured from start of current trial |
| rtStart | Stores the latency (in ms) from start of task until the Spacebar is pressed to see the first bead |
| rtDrawing | Stores the latency (in ms) from presentation of first bead to pressing 'D' (decision) |
| selectedjar | Stores the jar participant selects |
| decision | "correct" vs. "incorrect" |
| beadCount | Counts the number of beads drawn |
| bead | 1 = the higher probability bead color is selected 2 = the lower probability bead color is selected |
| beadSequence | Stores the bead sequence (e.g. R, R, B, R, R, R, ....) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
| typeDrawing | "random" vs. "predetermined" ! if "predetermined" go to 'Editable Lists' and edit list.beadsequence_predetermined (default list from Garety et al, 1991, condition 2) as well as set parameters.max_drawings below. ! Be aware that if you run more than one trial with the predetermined list, the script will always use the same list. | "random" |
| maxDrawings | "unlimited" vs. an integer e.g. /nr_drawing = 20 if the number of maximum beads is limited, the instructions under item.instructions may need to be edited accordingly | "unlimited" |
| feedback | True = participants receive feedback at the end (default) false = participants receive no feedback at the end | |
| numberOfTrials | Number of jar task trials to run by this script to run more trials add additional jar images and jar information under section Editable Stimuli (this script provides the images to run 2 trials) | 1 |