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									PROBABILISTIC REWARD TASK
SCRIPT INFO

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 09-22-2015
last updated: 01-21-2016 by K.Borchert (katjab@millisecond.com) for Millisecond Software LLC

Copyright © 01-21-2016 Millisecond Software


BACKGROUND INFO

											*Purpose*
This script implements a Probabilistic Reward Task as described in:

Pizzagalli, D.A., Jahn, A.L, & O’Shea, J.P. (2005). Toward an Objective Characterization of an Anhedonic
Phenotype: A Signal-Detection Approach. Biol Psychiatry, 57(4), 319–327.


											  *Task*
Participants are asked to categorize faces into "short" and "long" mouths. Correct responses are 
intermittedly rewarded with an asymmetric reinforcement schedule for short and long mouths.
For half the participants short mouths get reinforced about 60% of the times ("frequent reward") whereas long mouths
get reinforced only about 20% of the times ("infrequent reward"); for the other half of the participants the reverse is true.
Responsekeys are counterbalanced within groups.
Assignment to the 4 experimental condition (2 reinforcement schedules x 2 response keys assignments) is done by
groupnumber.


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

(1) Raw data file: 'ProbabilisticRewardTask_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 
/expgroup:						1 = short mouth is frequently rewarded; 2 = long mouth is frequently rewarded
/responsekeyassignment:			1 = short mouth left/long mouth right; 2 = short mouth right/long mouth left
blockcode, blocknum:			the name and number of the current block
/blockcount:					counts the blocks
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) 

/reward_short:					0 = short mouth trial is not supposed to be rewarded; 
								1 = short mouth trial is supposed to be rewarded (if response is correct; otherwise the next short trial that is correct is rewarded)
/new_reward_short:				0 = no new values.reward_short (this happens if the last short mouth trial was supposed to be rewarded but response was incorrect)
								1 = a new values.reward_short needs to be determined
/reward_long:					0 = long mouth trial is not supposed to be rewarded; 
								1 = long mouth trial is supposed to be rewarded (if response is correct; otherwise the next log trial that is correct is rewarded)
/new_reward_long:				0 = no new values.reward_long (this happens if the last long mouth trial was supposed to be rewarded but response was incorrect)
								1 = a new values.reward_long needs to be determined
stimulusitem:					the presented stimuli in order of trial presentation
response:						the participant's response
correct:						the correctness of the response (1 = correct; 0 = incorrect)

latency: 						the response latency (in ms); measured from onset of target
/total:							stores the currently total cents won (across test blocks)
/countrewardtrials:				counts the number of rewards given out (across test blocks)

(2) Summary data file: 'ProbabilisticRewardTask_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
/expgroup:						1 = short mouth is frequently rewarded; 2 = long mouth is frequently rewarded
/responsekeyassignment:			1 = short mouth left/long mouth right; 2 = short mouth right/long mouth left
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)
/countrewardtrials:				counts the number of rewards given out (across test blocks)
/total:							the total earned in $ amounts

Notes: 
No outlier removal

/propcorrect:					overall proportion correct -across all test trials-
/meanRT:						overall mean response latency (in ms) of correct responses - across all test trials
/propcorrect_frequent:			proportion correct frequently rewarded mouth trials
/meanRT_frequent:				mean latency (in ms) of correct frequently rewarded mouth trials
/propcorrect_infrequent:		proportion correct infrequently rewarded mouth trials
/meanRT_infrequent:				mean latency (in ms) of correct infrequently rewarded mouth trials
/logd:							Measure of Discriminability (see Pizzagalli et al, 2005, p.5)
/logb:							Measure of Response Bias  (see Pizzagalli et al, 2005, p.5)

EXPERIMENTAL SET-UP

2 reward frequency schedules x 2 response key assignments: Assignment to the 4 experimental groups is done by groupnumber

group 1 (odd groupnumbers)-> short mouth faces are frequently rewarded if response is correct (potentially 30 out of 50 trials ); long mouth faces are infrequently rewarded if correct (potentially 10 out of 50 trials)
group 2 (even groupnumbers)-> long mouth faces are frequently rewarded if response is correct (potentially 30 out of 50 trials ); short mouth faces are infrequently rewarded if correct (potentially 10 out of 50 trials)
within those groups, response key assignments are counterbalanced


1. Practice Block: 
* a short demonstration of 2 trials
* 2 trials, 1 of short mouth faces and 1 of long mouth faces (same durations as test trials )

2. Test Blocks: 
* 3 Blocks, each block runs 100 trials (50 short mouth trials, 50 long mouth trials)
* order of short and long mouth trials is randomly determined with the constraint that 
no more than 3 consecutive uns of the same trial type
* frequently rewarded mouth trials: 30 (30/50->60%); infrequently rewarded mouth trials: 10 (10/50->20%)
	-> per block there are 40 potential reward trials 
(Note: if participants make mistakes during reward trials, the actual number of rewarded trials MIGHT be lower)
	-> the reinforcement schedules for each trial type are randomized (see section Editable Lists for more info)
	-> if a trial has been randomly determined to be a rewarded trial but the response is incorrect, the next
	correct trial of the same trial type is rewarded instead
* there is a forced 30s (default) rest period inbetween each test block; the task continues automatically

Trial Sequence:
fixation (500ms)->No Mouth Face->(500ms)->Mouth Face(100ms)->No Mouth Face until response (response latency is taken and measured from onset of Mouth Face)

STIMULI
Face Stimuli are not original to Pizzagalli et al (2005). They can be edited under section Editable Stimuli.
(The default short mouth is about 88% of the long mouth).
Sizes of stimuli on screen are proportional to the monitor/canvas size; they can be adjusted under
section Editable Parameters.

INSTRUCTIONS
Instructions are not original to Pizzagalli et al (2005). They can 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:

/responsekeyleft:					the scancode of the left response key (default: 18 -> E)
										Note: Menu -> Tools -> Keyboard Scancodes
/responsekeyleft_label:				the label of the left response key (default: "E")
/responsekeyright:					the scancode of the right response key (default: 23 -> I)
/responsekeyright_label:			the label of the right response key (default: "I")

/fixationduration:					the duration of the fixation stim in ms (default: 500)
/signalduration:					the duration of the signal (face without mouth) before target appears in ms (default: 500)
/targetduration:					the duration of the target (face with mouth) in ms (default: 100)
/ITI:								the duration of the intertrial interval in ms (default: 0)
/feedbackduration:					the duration of the feedback stim in ms (default: 1750)
/restduration:						the duration of the rest trial inbetween blocks in ms (default: 30000)

/fixationheight:					the size of the fixation stim in % of canvas height (default: 10%)
/picsize:							the size of the face images in % of canvas size (default: 80%)
/feedbackheight:					the size of the feedback stim in % of canvas size (default: 6%)
/rewardamount:						the size of the reward in cents (default: 5)

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