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JUMPING TO CONCLUSION (JTC) - BEADS TASK ("Jar Task")
(German version)
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 10-28-2014
last updated: 09-30-2022 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 09-30-2022 Millisecond Software
Millisecond Software thanks Sarah Reeve for assistance with this script!
Translation by K. Borchert for Millisecond Software
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BACKGROUND INFO
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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.
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TASK DESCRIPTION
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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.
Note: This script includes the code to run more than one trial.
By default, only 1 trial is run.
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DURATION
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the default set-up of the script takes appr. 1 minute to complete
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DATA FILE INFORMATION
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The default data stored in the data files are:
(1) Raw data file: 'jtc_beadtask_raw*.iqdat' (a separate file for each participant)
build: The specific Inquisit version used (the 'build') that was run
computer.platform: the platform the script was run on (win/mac/ios/android)
date, time: date and time script was run
subject, group, with the current subject/groupnumber
session: with the current session id
blockcode, blocknum: the name and number of the current block (built-in Inquisit variable)
trialcode, trialnum: the name and number of the currently recorded trial (built-in Inquisit variable)
Note: trialnum is a built-in Inquisit variable; it counts all trials run;
even those that do not store data to the data file such as feedback trials
type_drawing: "random" vs. "predetermined" (can be set under section Editable Parameters)
max_drawings: "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
jarA_balls,: stores the ratio of red to blue beads in jar A (default: "85R:15B")
jarB_balls,: stores the ratio of red to blue beads in jar B (default: "15R:85B")
bigger_p: the probability of the colored beads with the larger amount
Target Jar: "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
rt_start: stores the latency (in ms) from start of task until the Spacebar is pressed to see the first bead
rt_drawing: 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, ....)
(2) Summary data file: 'jtc_beadtask_summary*.iqdat' (a separate file for each participant)
inquisit.version: Inquisit version run
computer.platform: the platform the script was run on (win/mac/ios/android)
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 = script was not completed (prematurely aborted);
1 = script was completed (all conditions run)
type_drawing: "random" vs. "predetermined" (can be set under section Editable Parameters)
max_drawings: "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
meanrt_drawing: mean latency (in ms) of trial.beaddrawing
medianrt_drawing: median latency (in ms) of trial.beaddrawing
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EXPERIMENTAL SET-UP
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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
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STIMULI
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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).
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INSTRUCTIONS
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The provided instructions are provided by Millisecond Software and can be edited under
section Editable instructions.
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EDITABLE CODE
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check below for (relatively) easily editable parameters, stimuli, instructions etc.
Keep in mind that you can use this script as a template and therefore always "mess" with the entire code
to further customize your experiment.
The parameters you can change are:
/type_drawing: "random" vs. "predetermined" (default: "random")
!Note: 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.
/max_drawings: "unlimited" vs. an integer e.g. /nr_drawing = 20 (default: "unlimited")
Note: if the number of maximum beads is limited, the instructions under item.instructions may
need to be edited accordingly
/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 (default: 1)
Note: to run more trials add additional jar images and jar information under section Editable Stimuli
(this script provides the images to run 2 trials)
