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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: 11-07-2019 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 11-07-2019 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: scancode of responsekey 1 (default: 45)
/responsekey_label_T2_1: responsekey 1 label (default: 'X')
/responsekey_T2_2: scancode of responsekey 2 (default: 44)
/responsekey_label_T2_2: responsekey 2 label (default: 'Z')