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This task is an AX-Continuous Performance Test (AX-CPT) designed to assess cognitive control and context processing. Participants are presented with a series of letter pairs (cue followed by probe). They must make a specific target response only when the cue is an 'A' and the probe is an 'X' (AX trials). For all other combinations (AY, BX, BY), a different response (or no response) is required.
2. Task Flow
Block-Level Flow
Step
Description
1. Instruction
Instructions are displayed at the beginning of the experiment.
2. Trial Execution
Each block runs for a set number of trials, as defined in config.yaml.
3. Block Break
After each block, a break screen is shown with the accuracy for the current block.
4. Goodbye
After all blocks are complete, a "goodbye" message is displayed.
Trial-Level Flow
Step
Description
1. Fixation
A central fixation cross (+) is displayed.
2. Cue Presentation
The cue letter (A or B) is presented.
3. Inter-Stimulus Interval (ISI) Fixation
A central fixation cross (+) is displayed for a short duration.
4. Probe Presentation & Response
The probe letter (X or Y) is presented, and the participant responds.
4. Feedback
Feedback (Correct, Incorrect, or Too Slow) is displayed.
5. Inter-Trial Interval (ITI)
A blank screen is shown before the next trial.
Runtime Context Phases
Phase Label
Meaning
context_cue
context cue stage in src/run_trial.py responder context.
delay_fixation
delay fixation stage in src/run_trial.py responder context.
probe_response
probe response stage in src/run_trial.py responder context.
3. Configuration Summary
a. Subject Info
Field
Meaning
subject_id
Subject Identifier
subname
Subject Name
age
Age
gender
Gender
b. Window Settings
Parameter
Value
size
[1920, 1080]
units
deg
screen
1
bg_color
gray
fullscreen
True
monitor_width_cm
60
monitor_distance_cm
72
c. Stimuli
Name
Type
Description
fixation
text
Central cross +.
cue_A
text
The cue letter 'A'.
cue_B
text
The cue letter 'B'.
probe_X
text
The probe letter 'X'.
probe_Y
text
The probe letter 'Y'.
correct_feedback
text
"正确" (Correct) in white.
incorrect_feedback
text
"错误" (Incorrect) in white.
no_response_feedback
text
"未反? (No response) in white.
instruction_text
textbox
Instructions explaining the task.
instruction_text_voice
voice
Voice instructions for the task.
block_break
text
Feedback shown between blocks.
good_bye
text
Final message at the end of the task.
d. Timing
Phase
Duration (s)
Config Variable
fixation
0.5
fixation_duration
cue
0.5
cue_duration
isi
0.5
isi_duration
probe
1.0 (max response time)
probe_duration
feedback
0.5
feedback_duration
iti
random 0.8?.2
iti_duration
e. Triggers
Event
Code
exp_onset
98
exp_end
99
block_onset
100
block_end
101
cue_onset
10
probe_onset
20
AX_trial_onset
30
AY_trial_onset
31
BX_trial_onset
32
BY_trial_onset
33
key_press
40
no_response
41
feedback_correct_response
51
feedback_incorrect_response
52
feedback_no_response
53
feedback_onset
60
4. Methods (for academic publication)
Participants perform an AX-CPT task, a continuous performance paradigm used to measure cognitive control and context processing. Each trial consists of a cue letter (A or B) followed by a probe letter (X or Y). Participants are instructed to press the 'f' key if the cue is 'A' and the probe is 'X' (AX trials). For all other cue-probe combinations (AY, BX, BY), they are instructed to press the 'j' key.
The task begins with a fixation cross, displayed for 500ms. The cue letter is then presented for 500ms, followed by a brief inter-stimulus interval (ISI) fixation of 500ms, and then the probe letter for up to 1000ms or until a response is made. Feedback (correct, incorrect, or no response) is provided for 500ms, followed by a randomized inter-trial interval between 800ms and 1200ms.
The task is structured into 4 blocks of 40 trials each (total 160 trials). Trial types (AX, AY, BX, BY) are presented in a weighted randomized order within each block (AX=40%, AY=10%, BX=10%, BY=40%) to preserve strong context expectancy while retaining critical low-frequency AY/BX control trials. This design allows for the examination of proactive and reactive cognitive control strategies.
