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											SIMPLE ATTENTIONAL BLINK 
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Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 11-04-2013
last updated:  03-06-2020 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC

Script Copyright © 03-06-2020 Millisecond Software

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BACKGROUND INFO 	
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This script implements a simple Attentional Blink design to study the temporary suppression of visual attention.
Attentional Blink: Reduced Processing of a second target (T1) that follows in short succession of a first target (T1)

The implemented design is inspired by:

Raymond, J.E.; Shapiro, K. L.; Arnell, K. M. (1992) Temporary suppression of visual processing in an RSVP task: 
An attentional blink? Journal of Experimental Psychology: Human Perception and Performance, Vol 18(3), 849-860.

and:

Folk, C.L, Leber, A.B., Egeth, H.E. (2002). Made you blink! Contingent attentional capture produces 
a spatial blink. Perception & Psychophysics, 64, 741-753.

Differences between script and Raymond et al (1992):
1. script uses constant stream length (see Folk et al, 2002) whereas Raymond et al (1992) used variable stream length 
2. reduced number of T1 stream positions and a reduced number of T1-T2 lag positions
3. T2 Task: in Raymond et al (1992) T2 was an X that could either be present or active. In this script, T2 is an X or a Z.
4. screencolor and color of letters and targets differ from Raymond et al (1992)

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TASK DESCRIPTION	
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Participants see a stream of non-repeating 20 letters. One of these letters is a red. This is target T1. 
It appears at predetermined positions (here: streampositions 5 or 10). Another letter might be an X or a Z. 
This is called the T2 stimulus. 

The T2 stimulus appears after the T1 stimulus in the stream at predetermined lags (here: lags 1 or 7). 
At the end of the sequence,  participants have to recall the red letter (T1) and decide whether 
they saw an X or a Z.

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DURATION 
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the default set-up takes app. 30 minutes 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: 'simpleattentionalblink_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
script.sessionid:					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. Thus, trialnum 
										may not reflect the number of main trials run per block. 
									
parameters.random_lettercolor:		true (default): the regular letters in the stream will be assigned random colors.
									(with exception of parameters.T1_color/parameters.T2_color). See list.randomlettercolors for details
									false: the regular letters will be presented in the color specified under parameters.lettercolor									
									
values.t1_streamposition:			holds the current temporal streamposition of the T1 stimulus
values.t2_lag:						holds the current T1-T2 lag (Note: lag = 1 => t2 is presented directly after t1)
values.t2_streamposition:			holds the current temporal streamposition of the T2 stimulus
values.t1_stim:						holds the name of the current T1 stimulus
values.t2_stim:						holds the name of the current T2 stimulus

response:							the participant's response (T1 task: openended response; T2 task: scancode for X (45) or Z (44))
correct:							the correctness of the response (1 = correct; 0 = error)
latency: 							the response latency (in ms)

letter1-
letter18:							store the 18 letters in the letter sequence (letters other than T1 and T2)
values.stream:						stream of letters in order of letter presentation	


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

computer.platform:					the platform the script was run on (win/mac/ios/android)
script.startdate:					date script was run
script.starttime:					time script was started
script.subjectid:					assigned subject id number
script.groupid:						assigned group id number
script.sessionid:					assigned session id number
script.elapsedtime:					time it took to run script (in ms); measured from onset to offset of script
script.completed:					0 = script was not completed (prematurely aborted); 
									1 = script was completed (all conditions run)


parameters.random_lettercolor:		true (default): the regular letters in the stream will be assigned random colors.
										(with exception of parameters.T1_color/parameters.T2_color). See list.randomlettercolors for details
									false: the regular letters will be presented in the color specified under parameters.lettercolor	
								
expressions.T1_meancorr_pos5lag1:		proportion correct responses to T1 task with T1 pos = 5 and T2 lag = 1
expressions.T1_meancorr_pos5lag7:		proportion correct responses to T1 task with T1 pos = 5 and T2 lag = 7
expressions.T1_meancorr_pos10lag1:		proportion correct responses to T1 task with T1 pos = 10 and T2 lag = 1
expressions.T1_meancorr_pos10lag7:		proportion correct responses to T1 task with T1 pos = 10 and T2 lag = 7

expressions.T2_meancorr_pos5lag1:		proportion correct responses to T2 task with T1 pos = 5 and T2 lag = 1
expressions.T2_meancorr_pos5lag7:		proportion correct responses to T2 task with T1 pos = 5 and T2 lag = 7
expressions.T2_meancorr_pos10lag1:		proportion correct responses to T2 task with T1 pos = 10 and T2 lag = 1
expressions.T2_meancorr_pos10lag7:		proportion correct responses to T2 task with T1 pos = 10 and T2 lag = 7

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EXPERIMENTAL SET-UP 
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- simple AB design with: 2 T1 streampositions x 2 T1-T2 lag positions x 2 T2 stimuli x 30 repetitions each = 240 trial sequences*
(repetitions in this script occur only if all possible 8 combinations have been run once)
	
Practice Block
- 12 practice trial sequences (same as test sequences but with error feedback)

Test Block Set-Up:
- 240 Trial Sequences
- random selection of T1 streamposition/lag/T2 with equal distribution of the two T2 across the 4 conditions T1streampositions x t1-t2 lags
- every 60 (default) trial sequences are followed by a rest trial

		Trial Sequence:
		- Fixation cross presentation for parameters.fixationduration (editable value)
		- A stream of 20* (default) white (or randomly colored) letters are presented: letters are randomly selected without replacement
		- one of the letters in the stream is red (default) => T1
		- one of the letters following the T1 is either an X or a Z => T2
		-> participants are asked to recall the T1 at the end of the stream
		-> participants are asked to press X if T2 = X or press Z if T2 = Z

		!!! Note: LETTER PRESENTATION TIME
		The letter presentation duration in this script is coded in terms of stimulusframes.
		On a monitor with a vertical refresh rate of 60Hz, one stimulusframe ~16.7ms.

		Each letter in this script is presented for 1 stimulusframe (~16.7ms on a 60Hz monitor)
		with a blank stimulus interval of 5 stimulusframes (~83.3ms on a 60Hz monitor)

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STIMULI
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Items can be edited under EDITABLE STIMULI; 
Text sizes can be edited under EDITABLE PARAMETERS

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INSTRUCTIONS 
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Instructions are provided by Millisecond Software
as htm/html pages and can be edited by changing the provided htm/html files.
To edit htm/html-files: open the respective documents in simple Text Editors such as TextEdit (Mac)
or Notepad (Windows). Additional instructions are listed 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:

/restperiods:								ratio of trialsequences to rests (aka there is a rest trial following every
											60 trial sequences - default)

Duration variables:
/restduration:								duration of rest trial in ms (default: 60000ms)
/fixationduration:							duration of fixation cross in ms (default: 500ms)
/responsecue_duration:						duration of the response cue in ms (default: 500ms) <= not in original article
									
Letter/targets:
/stimulussize_letters:						height of the letters relative to screen height (default: 10%)

/random_lettercolor							true: the regular letters in the stream will be assigned random colors.
											(with exception of parameters.T1_color/parameters.T2_color). See list.randomlettercolors for details												   
											false: the regular letters will be presented in the color specified under parameters.lettercolor
										
/lettercolor:								specifies the regular letter color if parameters.random_lettercolor == false
/T1_color:									specifies the color of T1 (default: red)
/T1_color_label:							the word label for T1 color (default: "RED")

/T2_color:									specifies a particular color for T2 
											(if left blank = "" => T2 gets the same color as regular stream letters)

/responsekey_T2_1:							response key 1 (default: 'X')	
/responsekey_T2_2:							response key 2 (default: 'Z')