This repository contains the stimulus code and relevant documentation for our EEG experiment investigating mismatch detection during object tracking. The experiment was developed in PsychoPy (2024.2.4) and designed as a visual oddball paradigm with dynamic motion stimuli.
Participants track a moving DVD-logo across a screen. The logo occasionally disappears (1.5s occlusion) and then reappears either in a predictable or unpredictable position and trajectory.
The code implements:
- Continuous motion and wall-bounce behavior
- Controlled occlusion and trajectory violation logic
- Parallel port triggers for EEG synchronization
- Attention check prompts
- Optional logic for near-corner detection and final disappearance event
Below are side-by-side examples of a predictable and an unpredictable reappearance:
| Predictable Trial | Unpredictable Trial |
|---|---|
 |
 |
Figure: The red 2D DVD logo used as the moving stimulus in the experiment.
| Trigger Value | Event Description |
|---|---|
| 1 | Experiment start |
| 2 | Baseline ends |
| 3 | Experiment end |
| 4 | Attention question appears |
| 5 | Attention question disappears |
| 10 | Disappearance (standard location) |
| 11 | Disappearance (near corner) |
| 200 | Predictable reappearance |
| 201 | Predictable reappearance (near corner) |
| 210 | Unpredictable reappearance |
| 211 | Unpredictable reappearance (near corner) |
| 40 | Participant response correct |
| 41 | Participant response incorrect |
| 98 | Final disappearance starts |
| 99 | Final disappearance ends (logo exits) |
experiment.py: Main PsychoPy scriptlogo.png: Visual stimulus used in the experimenttriggers.py: Parallel port trigger helper functionsoutput/: Folder with examples of output files (logfile and CSV)
This experiment was developed by:
- Agnes Margrethe Ottosen Gejl
- Anders Herzog Varan
- Lukas Kubiena
- Sissel Højgaard Vang-Pedersen (main author)
- Sofia Scharf-Matthiesen
This work was conducted as part of the Cognitive Neuroscience course, Aarhus University.
Gejl, A.M.O., Varan, A.H., Kubiena, L., Vang-Pedersen, S.H.*, & Scharf, S. (2025). EEG-Mismatch Detection in Cognitive Tracking. GitHub repository:(https://github.com/Siss1243/Neuro_experiment_2025.git)