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								PROBABILISTIC SELECTION TASK
SCRIPT INFO

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 04-08-2014
last updated: 02-25-2016 by K.Borchert (katjab@millisecond.com) for Millisecond Software LLC

Copyright © 02-25-2016 Millisecond Software


BACKGROUND INFO

											*Purpose*
This script implements the Probabilistic Selection Task as described in:

Frank, M.J., Seeberger, L.C. & O’Reilly. R.C. (2004). By Carrot or by Stick: Cognitive
Reinforcement Learning in Parkinsonism. Science, 306, 1940-1943.

Millisecond Software thanks J. Bianchi for collaborating on this script!


											  *Task*
Participants work through a learning and a test phase.
During the learning phase they get presented 3 symbol pairs (AB, CD, EF) and have to pick
the "winning symbol" of each pair. The win-probabilities of each symbol are controlled in 
such a way that A wins over B in 80% of the times; C wins over D in 70% of the times, and 
E wins over F in 60% of the times. The learning phase gets repeated if participants don't 
select the winning symbol with a pre-determined frequency.
During the test phase, novel symbol pairs are presented: the symbol that won the most (A)
is presented in AC, AD, AE, AF and the symbol that won the least (B) is presented in
BC, BD, BE, BF.											  


DATA FILE INFORMATION: 
The default data stored in the data files are:

(1) Raw data file: 'ProbabilisticSelectionTask_raw*.iqdat' (a separate file for each participant)

build:							Inquisit build
computer.platform:				the platform the script was run on
date, time, subject, group:		date and time script was run with the current subject/groupnumber 
blockcode, blocknum:			the name and number of the current block
trialcode, trialnum: 			the name and number of the currently recorded trial
									(Note: not all trials that are run might record data; by default data is collected unless /recorddata = false is set for a particular trial/block) 
stimulusitem:					the presented stimuli in order of trial presentation
									Note: does not need to correspond to spatial presentation of stimuli
/winletter:						contains the winning letter during learning
response:						the participant's response
/selectedletter:					contains the letter selected by participant during training and test phase
correct:						the correctness of the response
latency: 						the response latency in ms
/percA_AB-
/percE_EF:						calculates the percentage A/C/E selections for the training pairs (current training block)

(2) Summary data file: 'ProbabilisticSelectionTask_summary*.iqdat' (a separate file for each participant)

script.startdate:				date script was run
script.starttime:				time script was started
script.subjectid:				subject id number
script.groupid:					group id number
script.elapsedtime:				time it took to run script (in ms)
computer.platform:				the platform the script was run on
/completed:						0 = script was not completed (prematurely aborted); 1 = script was completed (all conditions run)
/percA_AB-
/percE_EF:						calculates the percentage A/C/E selections for the training pairs (last training block)

/percA_AC -
/percA_AF:						calculates the percentages of A-selections for all 4 test pairings with letter A

/percB_BC-
/percB_BF:						calculates the percentages of B-selections for all 4 test pairings with letter B					

/meanRT_AB-
/meanRT_EF:						calculates the mean decision latencies for the training pairs (last training block)

/meanRT_AC-
/meanRT_AF:						calculates the mean decision latencies for all 4 test pairings with letter A

/meanRT_BC-
/meanRT_BF:						calculates the mean decision latencies for 4 test pairings with letter B

EXPERIMENTAL SET-UP
Letter-Symbol-Assignment: each of the 6 symbols gets randomly assigned to 'play the role' of letters A-F

Learning Phase: 
* each learning block runs for 60 trials (20 per symbol pair -> can be edited via parameters.trialnumber_learning)
* for any given learning block the computer checks whether all learning criteria have been met during the given learning block
-> learning criteria: symbol A is selected at least 65% of the times, symbol C is selected at least 60% of the times, symbol E is selected at least 50% of the times
If those criteria haven't been met in the block, a new learning block starts

Test Phase:
* the test block runs for 160 trials (20 per symbol pair)

Trial Set-up:
The left-right position of the symbol pairs is counterbalanced across each block
-> symbol A appears on the left side in 50% of the trials 

STIMULI
The stimuli are the 6 Hiragana characters presented in Frank et al (2004).
Their size and location can be easily controlled via EDITABLE CODE -> Editable Values.

To use a different set of images, simply replace the stimuli under
section Editable Stimuli -> item.symbols

INSTRUCTIONS
The instructions are not the originals. They can easily be edited under section Editable
Instructions.

EDITABLE CODE:
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:

/responsekey_left:						scancode of the response key for symbol on the left (default: 30)
/responsekeyleft_label:					label of the response key for symbol on the left (default: "A")
/responsekey_right:						scancode of the response key for symbol on the right (default: 38)
/responsekeyright_label:				label of the response key for symbol on the right (default: "L")

/x_right:								horizontal coordinate of the right symbol in screen percentages (default: 35%)
/x_left:								horizontal coordinate of the left symbol in screen percentages (default: 65%)
/symbolheight:							the height of the symbol image in screen height percentages (default: 40%)

/trialnumber_learning:					the number of trials in a learning session (default: 60 -> 20 per symbol pair)
											Note: the minimum number for the default win probabilities and the balancing of left-right symbol presentation
											is 10 trials per symbol pair
											Note: the learning block gets repeated until specific learning criteria are met (see below) within a block
/minA_AB:								proportion of A-selections in AB pairs that have to be met in a learning block  (default: 0.65)
/minC_CD:								proportion of C-selections in CD pairs that have to be met in a learning block  (default: 0.6)
											Note: to remove a criterion, set the corresponding value to 0. In that case, any selection or none
											of the corresponding letter (A, C, E) fulfills the criterion.
/minE_EF:								proportion of E-selections in EF pairs that have to be met in a learning block  (default: 0.5)
/trialnumber_test:						the number of trials in the test session (default: 160 -> 20 per symbol pair)

/feedbackduration:						the duration of the feedback stimuli (default: 1000ms)

/winA_AB:								the winning proportion of A in AB pairs (default: 0.8)
/winC_CD:								the winning proportion of C in CD pairs (default: 0.7)
/winE_EF:								the winning proportion of F in EF pairs (default: 0.6)

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