Category: Help & Support Level: Beginner Reading time: 10 minutes Updated: 2026-01-23

Frequently Asked Questions (FAQ)

Quick Summary: Common questions about PEBL, the PEBL Online Platform, licensing, permissions, technical specifications, and system requirements.

What You'll Learn

Whether you need permission to use PEBL in your research
Current PEBL version and build information
Platform architecture and technology stack
Browser compatibility requirements
System specifications and limitations

Video Overview

New to PEBL Hub? Watch this 13-minute overview video that demonstrates how to use the platform:

📺 PEBL Hub Overview (13 minutes)

The video covers platform navigation, creating studies, configuring tests, and collecting data. For a step-by-step written guide, see Getting Started.

General Questions

Do I need permission to use PEBL software in my research study?

No, you do not need permission to use PEBL.

PEBL is free and open-source software licensed under the GNU General Public License (GPL) version 2. This means:

✅ You can use PEBL freely for any purpose:

Academic research
Clinical studies
Educational projects
Commercial applications
Personal projects

✅ No permission required to:

Run PEBL tests with participants
Modify PEBL tests for your needs
Publish research using PEBL
Cite PEBL in your papers

✅ No licensing fees:

PEBL is completely free
No cost per participant
No usage restrictions
No registration required

What is the GNU General Public License (GPL)?

The GPL is a free software license that guarantees users the freedom to use, study, share, and modify software.

Key points:

Freedom to use: You can run the software for any purpose without restriction
Freedom to study: Source code is available for you to examine and understand
Freedom to share: You can redistribute copies to help others
Freedom to modify: You can change the software to suit your needs

Important GPL requirement:

If you distribute modified versions of PEBL (give copies to others), you must also make your modifications available under the GPL
If you only use PEBL for research (without distributing modified versions), there are no additional requirements

Do I need to cite PEBL in my publications?

While not required by the license, citing PEBL is encouraged and appreciated:

Recommended citation:

Mueller, S. T., & Piper, B. J. (2014). The Psychology Experiment Building Language
(PEBL) and PEBL Test Battery. Journal of Neuroscience Methods, 222, 250-259.

For the PEBL Online Platform specifically, consider acknowledging:

Tests were administered using the PEBL Online Platform (https://peblhub.online),
which uses PEBL version [version] compiled to WebAssembly.

Can I modify PEBL tests for my research?

Yes, absolutely! The GPL explicitly grants you this right.

You can:

✅ Adjust test parameters (timing, trial counts, etc.)
✅ Change instructions or stimuli
✅ Translate tests to other languages
✅ Add or remove test components
✅ Create entirely new tests using PEBL

If you modify tests:

You do NOT need to share your modifications if you only use them internally
You MUST share modifications if you distribute them to others (but can do so through the platform's custom test upload feature)

Can I use PEBL for commercial purposes?

Yes! The GPL allows commercial use.

Examples of allowed commercial uses:

✅ Clinical assessment in private practice
✅ Corporate training programs
✅ Consulting services using PEBL tests
✅ Educational institutions (universities, schools)
✅ Research services companies

However:

You cannot remove the GPL license from PEBL
If you distribute modified PEBL software, it must remain GPL-licensed

Who created PEBL?

PEBL was created and is maintained by Dr. Shane Mueller (Michigan Technological University) and contributors from the research community.

Development history:

Original release: 2003
Current version: 2.2 (WebAssembly-enabled)
Active development: Ongoing
Community: Hundreds of researchers worldwide

More information:

PEBL website: http://pebl.sourceforge.net
Source code: https://sourceforge.net/projects/pebl/

Platform Version Information

What version of PEBL is the platform running?

PEBL Version: 2.3

Build Type: WebAssembly (Emscripten)

Git Commit: cb2eaa506e32494f77f54f9059a5c2d25479ea8e

Commit Date: 2026-01-21 23:19:31 -0500

Last Deployed: 2026-01-23

Note: Version information is automatically updated during deployment. The commit hash and date reflect the exact PEBL codebase currently running on the platform.

What is PEBL?

PEBL (Psychology Experiment Building Language) is a free, open-source programming language and software platform designed specifically for creating psychological experiments and cognitive tests.

Key Features

Cross-platform: Runs on Windows, macOS, Linux, and web browsers
Purpose-built: Designed specifically for psychological research
Free and open-source: No licensing fees or restrictions
Extensive library: 100+ pre-built cognitive tests
Multi-language support: Tests available in multiple languages
Precise timing: Millisecond-accurate response time measurement
Flexible: From simple reaction time tests to complex experimental designs

How is PEBL used in this platform?

The PEBL Online Platform compiles PEBL code to WebAssembly (Wasm), allowing PEBL tests to run directly in web browsers without requiring participants to install any software.

Technology Stack:

PEBL Language: C++-based interpreter compiled to JavaScript/Wasm
Emscripten: Compiler toolchain for C/C++ to WebAssembly
SDL2: Graphics and input handling (compiled to Wasm)
Virtual File System: Emscripten's FS API for data file access

Browser Requirements

Supported Browsers

The platform requires a modern web browser with WebAssembly support:

Desktop:

✅ Chrome 57+ (recommended)
✅ Firefox 52+
✅ Safari 11+
✅ Edge 16+ (Chromium-based)
✅ Opera 44+

Mobile (limited support):

⚠️ iOS Safari 11+ (some tests may have issues)
⚠️ Chrome for Android (some tests may have issues)
❌ Mobile browsers not recommended for complex cognitive tests

Required Features

Your browser must support:

✅ WebAssembly (Wasm)
✅ JavaScript ES6+
✅ HTML5 Canvas
✅ Web Audio API (for tests with sound)
✅ Fullscreen API (for fullscreen tests)
✅ IndexedDB (for local data caching)

Checking Browser Compatibility

Visit this page to verify your browser supports required features:

WebAssembly test: https://webassembly.org/

Platform Architecture

How do PEBL tests run in the browser?

Compilation: PEBL C++ interpreter is compiled to WebAssembly using Emscripten
Test Loading: PEBL test scripts (.pbl files) are loaded into virtual file system
Interpretation: WebAssembly PEBL interpreter executes test scripts
Rendering: Graphics rendered to HTML5 Canvas element
Data Collection: Results saved to virtual file system, then uploaded to server

What is WebAssembly?

WebAssembly (Wasm) is a binary instruction format that runs at near-native speed in web browsers. It allows languages like C++ to be compiled to run efficiently in browsers.

Benefits for PEBL:

Near-native performance (within 20% of native C++ speed)
No software installation required
Cross-platform compatibility
Secure sandbox environment
Access to web APIs (graphics, audio, networking)

Build Configuration

Emscripten Settings:

Optimization level: -O3 (production builds)
Memory: Initial 256MB, growable to 2GB
Filesystem: MEMFS (in-memory) + preloaded assets
Asyncify: Enabled (for event loops and timing)
SDL2 support: Full graphics, audio, input handling

Performance and Limitations

System Requirements

Minimum:

CPU: 2 GHz dual-core processor
RAM: 4 GB
Internet: 5 Mbps broadband connection
Display: 1024×768 resolution

Recommended:

CPU: 2.5 GHz quad-core processor
RAM: 8 GB
Internet: 10+ Mbps broadband connection
Display: 1920×1080 resolution

Platform Limitations

Data Storage:

Browser IndexedDB: ~50 MB per origin
Virtual filesystem: Limited by available RAM
Large datasets should be downloaded frequently

Network:

Test bundles cached locally after first load
Data uploads require stable internet connection
Offline mode not supported

Timing Precision:

Display timing: Limited by browser vsync (~60 Hz)
Input timing: ~1 ms precision (browser-dependent)
Audio timing: ~10-20 ms latency (Web Audio API)

Mobile Devices:

Touch input may not be suitable for all tests
Screen size limitations for complex layouts
Battery drain during long test sessions
Background app switching may interrupt tests

Version History and Updates

How often is PEBL updated?

The PEBL Online Platform is updated whenever significant improvements or bug fixes are made to the PEBL codebase.

Update frequency:

Bug fixes: As needed (immediate for critical issues)
New features: Monthly to quarterly
Test library updates: Ongoing as tests are developed

Where can I find the full PEBL changelog?

The complete PEBL development history is available in the Git repository:

Repository: https://sourceforge.net/p/pebl/git/
GitHub mirror: (if available)

What's the difference between PEBL versions?

PEBL 2.2 (current):

WebAssembly/Emscripten support
Modern SDL2 graphics
HTTP parameter loading
Improved translation system
Enhanced Layout.pbl library

PEBL 2.1 (previous):

SDL 1.2 graphics
Native builds only
Limited web support

PEBL 2.0:

Major rewrite with object-oriented design
Cross-platform support
Standard library expansion

Open Source and Licensing

Is PEBL open source?

Yes! PEBL is fully open source under the GNU General Public License (GPL) v2.

What this means:

✅ Free to use for any purpose (research, education, commercial)
✅ Source code is publicly available
✅ Can be modified and redistributed
✅ No licensing fees or restrictions
⚠️ Modifications must also be GPL-licensed

Where is the source code?

PEBL Core:

SourceForge: https://sourceforge.net/projects/pebl/
Git repository: https://sourceforge.net/p/pebl/git/

PEBL Online Platform:

(Repository URL if public)

How can I contribute?

Contributions to PEBL and the platform are welcome:

Report bugs and issues
Submit test improvements
Create new battery tests
Contribute translations
Improve documentation

Contact the maintainers for contribution guidelines.

Security and Privacy

Is the platform secure?

Security measures:

✅ HTTPS encryption for all data transmission
✅ WebAssembly sandbox isolates test execution
✅ Server-side validation of all uploads
✅ SQL injection protection
✅ XSS prevention in user inputs
✅ Regular security updates

What data is collected?

Participant data:

Test responses and reaction times
Browser user agent (for compatibility)
IP address (for geolocation analytics, anonymized)
Timestamps
Unique participant fingerprint (privacy-preserving)

Researcher data:

Account information (username, email, institution)
Study configurations
Usage statistics

See the Security & Privacy Guide for complete details.

Troubleshooting Technical Issues

Tests won't load or run

Check:

Browser supports WebAssembly (visit webassembly.org to test)
JavaScript is enabled
Browser is up to date
Clear browser cache and reload
Disable browser extensions (especially ad blockers)

Slow performance or lag

Try:

Close other browser tabs and applications
Use a wired internet connection
Ensure computer meets minimum requirements
Try a different browser (Chrome recommended)
Disable browser animations and effects

Data not saving