Flanker Task

Field	Value
Name	Eriksen Flanker Task
Version	main (1.0)
URL / Repository	https://github.com/TaskBeacon/Flanker
Short Description	A task measuring response inhibition and selective attention.
Created By	Zhipeng Cao (zhipeng30@foxmail.com)
Date Updated	2025/07/24
PsyFlow Version	0.1.0
PsychoPy Version	2025.1.1
Modality	Behavior/EEG
Language	Chinese
Voice Name	zh-CN-YunyangNeural

1. Task Overview

The Eriksen Flanker Task is a classic experimental paradigm used to assess selective attention and response inhibition. Participants are presented with a central target stimulus (an arrow) flanked by other stimuli (arrows). They are instructed to respond to the direction of the central target while ignoring the flanking stimuli. The task measures how efficiently a participant can focus on a target and filter out distracting information.

2. Task Flow

Block-Level Flow

Step	Description
Load Config	Load task configuration from config.yaml.
Collect Subject Info	Display a form to collect participant demographics.
Setup Triggers	Initialize the trigger sender for EEG/fMRI synchronization.
Initialize Window/Input	Create the PsychoPy window and keyboard handler.
Load Stimuli	Load all visual stimuli defined in the config using StimBank.
Show Instructions	Present task instructions to the participant.
Loop Over Blocks	For each block: run trials, then compute and show block-level feedback.
Show Goodbye	Display a final thank you message.
Save Data	Save all recorded trial data to a CSV file.
Close	Close the trigger port and quit PsychoPy.

Trial-Level Flow

Step	Description
Fixation	Show a central fixation cross (+).
Stimulus	Present the Flanker stimulus (e.g., >>><>>).
Response	Record the participant’s key press (left or right).
Feedback	Display feedback (Correct, Incorrect, or Too Slow).
ITI	A blank screen shown for a random duration before the next trial.

3. Configuration Summary

a. Subject Info

Field	Meaning
subject_id	Unique participant ID (3 digits).
subname	Participant’s name (Pinyin).
age	Participant’s age.
gender	Participant’s gender.

b. Window Settings

Standard PsychoPy window settings for fullscreen display.

c. Stimuli

Name	Type	Description
fixation	text	Central cross +.
congruent_left	text	<<<<<
congruent_right	text	>>>>>
incongruent_left	text	>><>>
incongruent_right	text	<<><<
correct_feedback	textbox	“正确” (Correct) in green.
incorrect_feedback	textbox	“错误” (Incorrect) in red.
no_response_feedback	textbox	“太慢” (Too Slow) in orange.
instruction_text	textbox	Instructions explaining the task.
block_break	text	Inter-block message showing accuracy and RT.
good_bye	text	Final thank you message.

d. Timing

Phase	Duration (s)	Config Variable
fixation	0.5	fixation_duration
stimulus	1.0 (max response time)	stim_duration
feedback	0.5	feedback_duration
iti	random 0.8–1.2	iti_duration

e. Triggers

Event	Code
exp_onset	98
exp_end	99
block_onset	100
block_end	101
fixation_onset	1
congruent_stim_onset	10
incongruent_stim_onset	20
left_key_press	30
right_key_press	31
feedback_correct_response	51
feedback_incorrect_response	52
feedback_no_response	53
feedback_onset	60

4. Methods (for academic publication)

In this experiment, participants performed an Eriksen Flanker task to assess selective attention and response inhibition. Each trial began with a central fixation cross, displayed for 500 ms. Subsequently, a row of five arrows was presented in the center of the screen for up to 1000 ms or until a response was made. Participants were instructed to respond to the direction of the central arrow while ignoring the flanking arrows by pressing the ‘f’ key for a left-pointing central arrow or the ‘j’ key for a right-pointing central arrow. Following their response, feedback was provided for 500 ms, indicating whether the response was correct, incorrect, or too slow.

The task included two types of stimuli: congruent trials, where all arrows pointed in the same direction (e.g., ‘>>>>>’ or ‘<<<<<’), and incongruent trials, where the flanking arrows pointed in the opposite direction from the central target arrow (e.g., ‘>><>>’ or ‘<<><<’). These conditions were presented in a randomized order within each block.

The task was structured into 3 blocks of 60 trials each (total 180 trials), with equal numbers of each condition (congruent-left, congruent-right, incongruent-left, incongruent-right) in each block. After each block, participants received feedback on their accuracy and were given the opportunity to rest before continuing to the next block. The inter-trial interval varied randomly between 800 and 1200 ms to prevent anticipatory responses.

This design allows for the examination of cognitive control processes, specifically the ability to selectively attend to relevant information while suppressing interference from irrelevant information. The difference in performance (reaction time and accuracy) between congruent and incongruent trials provides a measure of the “flanker effect,” which reflects the cost of inhibiting conflicting information.

5. References

1. 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(1), 143-149.

2. Ridderinkhof, K. R., van der Molen, M. W., Band, G. P., & Bashore, T. R. (1997). Sources of interference from irrelevant information: A developmental study. Journal of Experimental Child Psychology, 65(3), 315-341.

3. Fan, J., McCandliss, B. D., Sommer, T., Raz, A., & Posner, M. I. (2002). Testing the efficiency and independence of attentional networks. Journal of Cognitive Neuroscience, 14(3), 340-347.