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									DIGITAL FOOD DISPENSER - Spacebar operated

Script Author: Katja Borchert, Ph.D. ( for Millisecond Software, LLC
Date: 07-07-2015
last updated: 01-08-2016 by K.Borchert ( for Millisecond Software LLC

Copyright © 01-08-2016 Millisecond Software


This script implements a Digital Food Dispenser similar to the one described in:

van Koningsbruggen, G.M., Veling, H., Stroebe, W. & Aarts, H. (2014). Comparing two psychological interventions in
reducing impulsive processes of eating behaviour: Effects on self-selected portion size.
British Journal of Health Psychology, 19, 767–782.

Participants view a food dispenser. By pressing the Spacebar down they "open" the Food Dispenser.
By lifting the Spacebar they "close" the Food Dispenser and end the session.

The default data stored in the data files are:

(1) Raw data file: 'DigitalFoodDispenser_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
response:						the participant's response
correct:						the correctness of the response (1 = correct; 0 = incorrect)
latency: 						the response latency (in ms)
/currentresponseduration:		the amount of time the Spacebar was pressed (in ms) for the current food dispenser
/currentpoints:					stores the points of the current food dispenser session (resets for each food dispenser)
/totalpoints:					stores the points earned across food dispensers

(2) Summary data file: 'DigitalFoodDispenser_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)
/maxpoints:						the maximum number of points that can be gained for one food dispenser (default: 500)
/meanresponseduration:			mean response duration in ms (how long Spacebar was pressed on average) across dispensers
/meanpoints:					mean points gained across dispensers (Max: 500)

* 2 trials: 1 food dispenser with cherries and 1 food dispenser with bananas; order is randomly determined
* Spacebar down: the dispenser "opens": fruit pieces "fall out" and a gray cover starts to cover the food dispenser
to simulate that it empties out
* Spacebar up: the dispenser "closes" -> trial comes to an end
* every 100ms (default) of pressing the Spacebar earns the participant 1 point => max. 500 points can be earned (then the dispenser is empty)

provided by Millisecond Software

provided by Millisecond Software; edit under section Editable Instructions

check below for (relatively) easily editable values, 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 values you can change are:

/increaseinterval:		another point is added for every 100ms (default; Note: should not be set lower than vertical refreshrate of monitor which is ~17ms for a 60Hz monitor)
                        that the Spacebar is NOT pressed
/maxpoints:				the maximum number of points that can be gained (default: 500)

Note: the product of increaseinterval and maxpoints controls how long it takes to 'drain' the dispenser completely

/finalcoverheight:		the height of the final gray cover (Note: should only be messed with if different pictures are used)

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