Simon Task
System Requirements
Minimum: 800×600
Recommended: 1024×768
Description
Simon's spatial stimulus-response compatibility task. Participants respond to stimulus color while ignoring its spatial location, demonstrating automatic processing of task-irrelevant spatial information.
About This Test
Participants see colored circles (default: red or blue) appearing at different horizontal positions on the screen. They respond to the color using left/right shift keys, ignoring the horizontal position. The spatial position creates compatibility conditions: compatible (color and position match), incompatible (color and position conflict), or neutral (stimuli appear near center). The task measures selective attention and inhibition of automatic spatial responses.
Test Details
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Scientific Background
Original Task References:
These references describe the original task that this PEBL implementation is based on.
- Simon, J. R., & Wolf, J. D. (1963). Choice reaction times as a function of angular stimulus-response correspondence and age. Ergonomics, 6, 99-105.
- Yamaguchi, M., & Proctor, R. W. (2012). Multidimensional vector model of stimulus-response compatibility. Psychological Review, 119, 272-303.
PEBL-Specific References:
These studies used the PEBL version of this task.
- Mueller, S. T. (2011). The PEBL Simon Interference Task. Computer software retrieved from http://pebl.sf.net/battery.html
Data Output
Creates two data files: (1) simon-<SUBNUM>.csv with trial-level data including stimulus type, position, compatibility, response, correctness, timestamps, and reaction times; (2) simon-summary-<SUBNUM>.txt with summary statistics organized by compatibility condition and by position/stimulus combinations.
Example Data
example-data.csv Primary
Trial-by-trial data with columns: subnum, trial, type (1=left color, 2=right color), pos (horizontal position in pixels from center, -200 to +200), compatible (1=compatible, 0=neutral, -1=incompatible), resp (key pressed: <lshift> or <rshift>), corr (1=correct, 0=incorrect), time (absolute timestamp in ms), rt (reaction time in ms)
| subnum | trial | type | pos | compatible | resp | corr | time | rt |
|---|---|---|---|---|---|---|---|---|
| example | 1 | 2 | 50 | 1 | <rshift> | 1 | 19130 | 364 |
| example | 2 | 2 | -200 | -1 | <rshift> | 1 | 20181 | 479 |
| example | 3 | 1 | -50 | 1 | <lshift> | 1 | 21460 | 402 |
| example | 4 | 2 | -100 | -1 | <lshift> | 0 | 22648 | 379 |
| example | 5 | 2 | -200 | -1 | <lshift> | 0 | 23718 | 523 |
| example | 6 | 2 | -50 | -1 | <rshift> | 1 | 24901 | 383 |
| example | 7 | 1 | -100 | 1 | <lshift> | 1 | 26014 | 403 |
| example | 8 | 1 | 0 | 0 | <lshift> | 1 | 27026 | 454 |
| example | 9 | 2 | 200 | 1 | <rshift> | 1 | 28091 | 424 |
example-data-summary.txt Summary
Summary statistics including: response times by compatibility condition (-1, 0, 1), response times by position/condition combinations, accuracy by compatibility, accuracy by position/condition. Each section reports N, median, mean, and SD.
| PEBL Simon Test: Summary data |
|---|
| PEBL Version 2.2 |
| Thu Nov 27 21:01:20 2025 |
| Response times (by compatibility): |
| condition N median mean sd |
| --------------------------------- |
| -1 24 382 455.333 181.053 |
| 0 8 395.5 523.875 302.224 |
| 1 24 407.5 429.042 103.884 |
| Response times (by position/Condition): |
Sample data showing typical output format. Actual values will vary by participant.
About This Test
Simon's spatial stimulus-response compatibility task. Participants respond to stimulus color while ignoring its spatial location, demonstrating automatic processing of task-irrelevant spatial information.
Category: Attention
Estimated Duration: 10 minutes
Available Translations: 8 languages
Documentation Sources:
Test description file, Test implementation, PEBL wiki archive, Parameter schema
Documentation Status: Standard