___________________________________________________________________________________________________________________ ERIKSEN FLANKER TEST ___________________________________________________________________________________________________________________ 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 ___________________________________________________________________________________________________________________ BACKGROUND INFO ___________________________________________________________________________________________________________________ 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. ___________________________________________________________________________________________________________________ TASK DESCRIPTION ___________________________________________________________________________________________________________________ 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 ___________________________________________________________________________________________________________________ DURATION ___________________________________________________________________________________________________________________ the default set-up of the script takes appr. 30+ minutes to complete ___________________________________________________________________________________________________________________ DATA FILE INFORMATION ___________________________________________________________________________________________________________________ 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 ___________________________________________________________________________________________________________________ EXPERIMENTAL SET-UP ___________________________________________________________________________________________________________________ (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 Courier New, 0.5cm: can be changed under EDITABLE VALUES (parameters.fontheight_innm) Note: If Monospaced Courier New 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. ___________________________________________________________________________________________________________________ STIMULI ___________________________________________________________________________________________________________________ target letters: H, K (angular), S, C (curved) ___________________________________________________________________________________________________________________ INSTRUCTIONS ___________________________________________________________________________________________________________________ Instructions are not original and can be easily edited under section 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: 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)