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ERIKSEN FLANKER TEST
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 09-19-2012
last updated: 06-15-2023 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 06-15-2023 Millisecond Software
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BACKGROUND INFO
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This script implements the original Flanker Test procedure by Eriksen & Eriksen (1974).
The Flanker test is an inhibition test to assess the ability to suppress inappropriate responses
evoked by task irrelevant information.
Reference:
Eriksen, B.A. & Eriksen, C.W (1974) Effects of noise letters upon the identification of a target letter
in a nonsearch task. Perception & Psychophysics, 16, 143-149.
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TASK DESCRIPTION
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simple categorization task of 4 target letters (H, K, S, C) that appear above a fixation cross
into "angular" vs. "curved" categories.
=> Press "Q" if it's H or K, press "P" if it's S or C.
Target letters can appear alone ("nonoise") or be flanked by noise letters ("noise") that can
either be close together or far apart.
Note: Responsekeys
*can be changed under EDITABLE VALUES.
*are counterbalanced by odd and even subjectnumbers
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DURATION
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the default set-up of the script takes appr. 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: 'flankertest_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
session: 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.
trialcount: counts the number of trials
responsecondition: counterbalanced response key condition
noisecondition: stores the current noise condition (1-5)
1) noise equal to target: all 6 noise letters = target letter (e.g, HHHHHHH)
2) noise similar to target: all 6 noise letters = the other letter in the target category (e.g. KKKHKKK)
3) noise other target set: all 6 noise letters = one of the letters of the opposite target category (e.g. SSSHSSS)
Note: choice of letter of opposite target category is balanced across experiment
4) noise similar to target: noise = 3 letters that have similar characteristics (e.g. NWZHNWZ)
Note: position of the three letters balanced across experiment
5) noise dissimilar to the target: noise = 3 letters with dissimilar characteristics (e.g. QJGHQJG)
Note: position of the three letters balanced across experiment
spacingcondition: stores the current spacing condition (1-3)
trialtype: contains all trialinformation
(Example: "K53B" -> target K, condition 5, spacing 3,
B=refers to one of three possible rotations of the noise stimuli in condition 5)
stimulusitem.-
stimulusitem.4: the presented stimuli
response: the participant's response (scancode of response buttons)
16 = Q (left)
25 = P (right)
correct: accuracy of response: 1 = correct response; 0 = otherwise
latency: the response latency (in ms); measured from onset of stimuli
(2) Summary data file: 'FlankerTest_summary*.iqdat' (a separate file for each participant)
inquisit.version: Inquisit version run
computer.platform: the platform the script was run on (win/mac/ios/android)
startDate: date script was run
startTime: time script was started
subjectid: assigned subject id number
groupid: assigned group id number
sessionid: assigned session id number
elapsedTime: time it took to run script (in ms); measured from onset to offset of script
completed: 0 = script was not completed (prematurely aborted);
1 = script was completed (all conditions run)
properror_noise1-
properror_noise5: error proportion, separately for each noise condition
properror_spacing1-
properror_spacing3: error proportion, separately for each spacing condition
properror_nonoiseM: error proportion of nonoise trials tested in a mixed (M) design
properror_nonoiseB: error proportion of nonoise trials tested in a blocked (B) design
meanRT_noise1-
meanRT_noise5: mean latency of correct responses, separately for each noise condition
meanRT_spacing1-
meanRT_spacing3: mean latency of correct responses, separately for each spacing condition
meanRT_nonoiseM: mean latency of correct responses to nonoise trials tested in mixed (M) design
meanRT_nonoiseB: mean latency of correct responses to nonoise trials tested in blocked (B) design
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EXPERIMENTAL SET-UP
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(A) DESIGN:
3 (spacings) x 5 (noise conditions) tested within participants,
2 control conditions of nonoise targets tested in a mixed vs. blocked format within participants
(B) SESSION SET-UP:
6 experimental sessions (see Eriksen & Eriksen, 1974, p.146)
1 experimental session: 3 blocks.Mixed (3*32 trials = 3*(28 noisetrials + 4 nonoisetrials)) + 1 block.blocked (12 nonoisetrials)
= 6*3*28 noisetrials + 6*3*4 nonoisetrials(mixed) * 6*1*12 nonoisetrials(blocked)
= 504 noisetrials + 72 nonoisetrials(mixed) + 72 nonoisetrials(blocked)
=> nonoisetrials:
nonoisetrials per target letter (4 letters) in mixed and blocked format= 72/4= 18 (see Eriksen & Eriksen, 1974, p.146)
=> noisetrials:
noisetrials per letter spacing condition (3 spacing conditions)= 504/33 = 168
noisetrials per letter spacing condition per noise conditions (5+2* conditions) = 168/7 = 24 (see Eriksen & Eriksen, 1974)
noisetrials per letter spacing condition per noise conditions per letter (4)= 24/4 = 6
(C) INDEPENDENT VARIABLES:
1. SPACING CONDITIONS: Eriksen & Eriksen (1974)
1)about 0.06 degree visual angle separation (depends on viewing distance and font size) -
2)about 0.5 degree visual angle separation (depends on viewing distance and font size)
3)about 1 degree visual angle (depends on viewing distance and font size)
(4) distance from target to fixation cross: 0.5 degree visual angle)
!!!Note: SPACING = NEEDS FINE TUNING
the default coordinates for the noise stimuli in this script are only
rough approximations. They need to be fine-tuned by each experimenter.
Specifically: fine tune
*distance target-to-fixation cross under EDITABLE VALUES (parameters.fix_distance)
*spacings between stimuli under EDITABLE VALUES (parameters.spacing1, parameters.spacing2, parameters.spacing3)
*fontstyle: Erikson & Erikson (1974) used Paratipe 18point Futura Bold Style,
=> this script uses Monospaced Lucida Console, 0.5cm: can be changed under EDITABLE VALUES (parameters.fontheight_innm)
Note: If Monospaced Lucida Console is not available try a different monospaced fontstyle
2. NOISE CONDITIONS:
1) noise equal to target: all 6 noise letters = target letter (e.g, HHHHHHH)
2) noise similar to target: all 6 noise letters = the other letter in the target category (e.g. KKKHKKK)
3) noise other target set: all 6 noise letters = one of the letters of the opposite target category (e.g. SSSHSSS)
Note: choice of letter of opposite target category is balanced across experiment
4) noise similar to target: noise = 3 letters that have similar characteristics (e.g. NWZHNWZ)
Note: position of the three letters balanced across experiment
5) noise dissimilar to the target: noise = 3 letters with dissimilar characteristics (e.g. QJGHQJG)
Note: position of the three letters balanced across experiment
*Note:
Eriksen & Eriksen (1974) ran double the amount of trials in noise conditions 4 and 5 than in the remaining 3 conditions
(refer to Eriksen & Eriksen, 1974, Table 3, p.147), numberwise this is equivalent to running 7 conditions
(D) BLOCKS:
Each block.mixed runs 32 trials: 7 H-trials, 7 K-trials, 7 S-trials, 7 C-trials, as well as
4 nonoise trials (one of each letter).
Trials are randomly chosen without replacement.
3 blocks make up 1 experimental session:
Every combination of letter x spacing condition x noise condition is run once (combinations of
noise condition 4 and 5 are run twice),
H: 1(=noise condition)1(=spacing condition),12,13,21,22,23,31,32,33,41,42,43,41,42,43,51,52,53,51,52,53
K: 11,12,13,21,22,23,31,32,33,41,42,43,41,42,43,51,52,53,51,52,53
S: 11,12,13,21,22,23,31,32,33,41,42,43,41,42,43,51,52,53,51,52,53
C: 11,12,13,21,22,23,31,32,33,41,42,43,41,42,43,51,52,53,51,52,53
Balancing of the different letter rotations/selections of noise conditions 3 (selection), 4 (rotation), 5 (rotation)
is achieved across all 6 experimental sessions (but not across a single experimental session).
This script runs all 6 experimental sessions in a row.
Each block.blocked runs 12 nonoise trials, 3 of each of the 4 target letters. Letters
are randomly sampled without replacement.
(E) TRIALS:
*Fixation Cross => press Space Bar to bring on target (and noise letters)
*target appears directly above Fixation Cross
(NOTE: Eriksen & Eriksen, 1974: 1/2 degree visual angle above,
the location in this script is only a rough approximation and needs fine-tuning under EDITABLE VALUES)
*noise letters appear flanking the target (in noise trials),
type of noise letters depends on noise condition, spacing depends on spacing condition
Notes:
* In Eriksen & Eriksen (1974) the target and noise letters remained on the screen for 1s (regardless of whether
a response is given) and then disappeared together. In this script the response terminates the trial.
* In Eriksen & Eriksen (1974) error trials were repeated later in the session. In this script, error trials
are not rerun.
PRACTICE:
By default, three blocks of 32 trials are given as practice. Number can be edited under section EDITABLE PARAMETERS.
During practice, participants receive feedback if they make a mistake.
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STIMULI
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target letters: H, K (angular), S, C (curved)
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INSTRUCTIONS
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Instructions are not original and can be easily edited under section 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:
Stimuli Sizing in mm:
/fontheight_inmm: fontheight in cm (default: 0.5cm)
/screenheight: the height of the monitor that the experiment runs on
/fixed_distance_inmm: the distance of the target stimuli from the fixation cross in mm (default is 10mm)
/spacing1_inmm: the distance between stimuli in spacing condition 1 in mm (default is 3mm)
/spacing2_inmm: the distance between stimuli in spacing condition 2 in mm (default is 10mm)
/spacing3_inmm: the distance between stimuli in spacing condition 3 in mm (the default is 20mm)
Response Keys:
/leftkey: left responsekey (default: "Q")
/rightke2: right responsekey (default: "P")
Experimental Design:
/maxpracticeblocks: determines how many practice blocks should be run (default: 3
equivalent to one experimental session)
/trialtimeout: the max. trial duration (in ms) (default: 1000ms)
/trialdelay: the delay (in ms) of the trial after pressing the spacebar (default; 0ms)
