The Fusion mobile app supports running jsPsych experiments directly on participants’ phones and tablets. Experiments render in a WebView with automatic orientation handling and local-first data storage.
How It Works
- Participant opens the quest in the Fusion mobile app
- Taps on an experiment card to start
- The experiment loads in a full-screen WebView
- Screen locks to landscape orientation for the duration of the experiment
- When the experiment calls
jatos.endStudy(data), the data is captured
- Screen returns to portrait orientation
- A completion alert shows the number of trials recorded
Data Flow
| Step | What Happens |
|---|
| Capture | jatos.endStudy() is intercepted by the React Native bridge |
| Local save | Data is saved to AsyncStorage immediately (offline-safe) |
| Server sync | Data is uploaded to Azure Blob Storage when connection is available |
| Dataset record | Saved as experiment_data with source mobile |
Data is saved locally first, so experiment data is not lost if the participant loses connectivity during or after the experiment. It syncs to the server automatically when a connection is available.
Differences from Web
| Feature | Web | Mobile |
|---|
| Orientation | No forced orientation | Locks to landscape during experiments |
| Data storage | Direct server upload | Local-first with background sync |
| CORS/CSP | Browser-handled | Auto-injected by the app |
| Error handling | Standard browser console | Captures console.error, unhandled rejections, and global errors |
| Export | Download from dashboard | Share as JSON file via device share sheet |
Export on Mobile
Participants can export their experiment data directly from the mobile app:
- Navigate to the completed experiment
- Use the export option
- Data is saved as a JSON file and shared via the device’s share sheet (AirDrop, email, Files, etc.)
This uses expo-file-system and expo-sharing under the hood.
When to Use Mobile vs. Web
| Use Case | Recommended |
|---|
| In-field / take-home studies | ✅ Mobile |
| Prolific recruitment | ✅ Web |
| EEG sessions with mobile app | ✅ Mobile |
| Large-screen experiments (complex layouts) | ✅ Web |
| Studies requiring precise keyboard input | ✅ Web |
| Participants without computer access | ✅ Mobile |
| Lab-based with shared computers | ✅ Web + Kiosk Mode |
Tips
Design your experiment layout to work well in landscape orientation on phone-sized screens. Test on actual devices before launching.
- Experiments run on both iOS and Android through the Fusion app
- The same experiment code works on both web and mobile — no separate version needed
- Mobile data is tagged with source
mobile so you can distinguish it from web data in your analysis
- If your experiment uses touch input instead of keyboard, it will work naturally on mobile
- Benign CORS “Script error.” messages are automatically filtered on mobile
