> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usefusion.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Running Experiments on Mobile

> Participants can complete experiments in the Fusion mobile app on iOS and Android.

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

1. Participant opens the quest in the Fusion mobile app
2. Taps on an experiment card to start
3. The experiment loads in a **full-screen WebView**
4. Screen **locks to landscape orientation** for the duration of the experiment
5. When the experiment calls `jatos.endStudy(data)`, the data is captured
6. Screen returns to **portrait orientation**
7. 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`                     |

<Info>
  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.
</Info>

## 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:

1. Navigate to the completed experiment
2. Use the **export** option
3. 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](/onboarding/kiosk-mode) |

## Tips

<Tip>
  Design your experiment layout to work well in **landscape orientation** on phone-sized screens. Test on actual devices before launching.
</Tip>

* 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