PEBL Release Notes

PEBL 2.4 — April 2026

PEBL 2.4 launches alongside the new OpenScales repository, bringing a graphical Scale Builder, Lab Streaming Layer integration, a consent system, and new battery tasks.

OpenScales & Scale Builder

  • This release coincides with the first release of OpenScales — a free, open collection of 555+ psychological scales in the Open Scale Definition (OSD) format
  • Browse the full OpenScales catalog from within the PEBL launcher and run any scale with one click
  • New graphical Scale Builder: create and edit OSD scales with Likert, multiple-choice, multi-select, text entry, and VAS response types
  • Sections, scoring dimensions, computed variables, score transforms, translations editor, and parameter configuration
  • Scales run natively in PEBL, on PEBL Hub online, or via a standalone JavaScript runner

Lab Streaming Layer (LSL)

  • New --lsl <StreamName> flag enables LSL marker output for any PEBL task
  • Synchronize experiment events with EEG, fMRI, eye tracking, and other physiological acquisition systems
  • "Waiting for LabRecorder" screen shown before the task begins for clean synchronization
  • Uses liblsl v1.17.5 with multicast UDP discovery — works across subnets and multiple machines
  • Chain builder supports per-task LSL configuration
  • Available on Linux and Windows

Consent System & Launcher Improvements

  • New Consent item type in the chain builder: declining consent cleanly terminates the study
  • DEMO-NIMH consent form included as a starting template
  • OpenScales browser tab added to launcher; Scale Builder integrated as first-class tab
  • Per-task LSL stream configuration in chains
  • Settings dialog expanded with upload server configuration

Battery & Language

  • New tasks: Digit Symbol Coding (digitsymbol), Pattern Comparison Same/Different (pattcomp-samediff), Pattern Comparison Sequential (pattcomp-seq), updated Spatial Cueing (spatialcueing)
  • Additional tasks migrated to online platform — approximately 80 tests now available online
  • New translations (de, es, fr, it, nl, pt) for plusminus, probrev, brownpeterson; Urdu for matchtosample and TOL
  • New RegexMatch() function for pattern matching
  • HTML-lite markup support in Label objects (bold, italic, color, font size)
  • Windows build fully modernized with MSYS2/MinGW; LSL ABI compatibility fixes; GCC 15 compatibility

PEBL 2.3 — January 2026

PEBL 2.3 brings a comprehensive Layout & Response System for cross-platform input handling, a native C++ launcher with study management, a standalone script validator, and a major expansion of the online platform test library.

Online Platform & Upload-Battery Expansion

  • Expanded upload-battery directory with 10 new platform-ready tests (total 58 tests)
  • New tests migrated to upload-battery:
    • Chimp Test (chimptest) — Iconic/eidetic and spatial memory assessment
    • Dual-Task Interference Test (dualtask) — Executive function and multitasking
    • Global-Local Processing Task (globallocal) — Attentional processing and visual perception
    • Line Judgment Task (linejudgment) — Visual perception and estimation
    • Matrix Rotation Task (matrixrotation) — Visuospatial reasoning
    • Dual N-Back Task (nback) — Working memory training and assessment
    • Span Variants Test (spanvariants) — Comprehensive memory span assessment
    • Time-Tapping Task (timetap) — Temporal perception and motor timing
    • Visual Search Task (vsearch) — Attention and visual processing
    • Even/Odd Task (evenodd) — Number processing and decision making
  • All newly migrated tests feature Layout & Response System integration
  • Enhanced frozen snapshot system for study version control on online platform
  • Improved bundle management for platform test deployment

Layout & Response System

  • Comprehensive platform-aware input handling system for cross-platform compatibility
  • Semantic response mapping (LEFT/RIGHT, YES/NO, etc.) independent of physical input device
  • Multiple response mode support: keyboard-safe, mousebutton, touchtarget, touchdrag, mousedrag
  • Automatic adaptation to platform capabilities (touch vs mouse vs keyboard)
  • Sticky Keys prevention for web browsers (avoids Windows accessibility dialog)
  • CreateLayout() function for UI setup with responsemode parameter
  • Unified response handling across native, WebAssembly, and mobile platforms
  • 18+ battery tests migrated to new response system
  • Detailed migration guide in doc/LAYOUT_MIGRATION_GUIDE.md

Native C++ Launcher & Development Tools

  • PEBL Launcher (pebl-launcher): Native C++ study management application using Dear ImGui
    • Visual study builder with drag-and-drop test organization
    • Chain creation for multi-task experiment sequences
    • Snapshot export/import system for study version control and sharing
    • ZIP-based snapshot format with metadata and bundled files
    • Subject ID management and data directory organization
    • Token-based upload configuration for PEBL Online Platform
    • Cross-platform support (Linux, planned Windows/macOS support)
    • libzip integration for snapshot packaging
  • PEBL Validator (pebl-validator):
    • Standalone syntax validation tool for PEBL scripts
    • Batch validation support for entire directories
    • Detailed error reporting with line numbers and context
    • Integration with development workflows
    • Available as separate binary for CI/CD pipelines

Network & Data Upload Improvements

  • Token-based authentication system in Transfer.pbl
    • New auth_token field replaces username/password for platform uploads
    • Backward compatibility maintained for legacy authentication
    • Unified authentication across native and WebAssembly builds
  • HTTPS upload fixes in PEBLHTTP.cpp
    • Automatic protocol detection based on port (443 = HTTPS, others = HTTP)
    • Full URL construction with protocol prefix for libcurl
    • Proper SSL/TLS handling for secure data transmission
    • Fixed port-based routing for encrypted uploads
  • Enhanced upload reliability and error handling
  • Improved network connection management

Build System Improvements

  • Fixed Emscripten JPEG support with correct SDL2_IMAGE_FORMATS configuration
  • Changed from "jpeg" to "jpg" format string with explicit USE_LIBJPEG=1 flag
  • Enhanced .gitignore patterns for build artifacts (test bundles, launcher binaries)
  • Improved bundle packaging workflow for online platform deployment
  • Separate handling of frozen snapshot bundles vs. core battery bundles

Battery Test Improvements

  • Fixed Iowa Gambling Task (iowa.pbl) syntax errors in language detection
  • Corrected indentation and brace placement in conditional blocks
  • Fixed nested if/else structure for translation file selection
  • Applied fixes to both battery/ and upload-battery/ versions
  • Removed legacy backup files (iowa-old.pbl) from upload-battery
  • Enhanced parameter schemas and translation support across migrated tests

Bug Fixes and Refinements

  • Fixed brace alignment and conditional nesting in language detection code
  • Improved error handling in token-based upload system
  • Corrected JPEG format specifier for SDL2_image in WebAssembly builds
  • Enhanced bundle metadata handling for platform deployment
  • Fixed snapshot bundle path resolution for active studies

Also Includes Changes from 2.2.1

  • Fixed GLR parser to allow 'else' statements on new line, improving code readability
  • Added Urdu language support with automatic font selection for Perso-Arabic script
  • Migrated TNT (Toulouse N-back Test) and Fitts' Law test to upload-battery
  • Added translations for multiple battery tests (German, Spanish, Italian, Dutch, Portuguese)
  • Audio format standardization: converted WAV files to OGG for better web compatibility
  • Improved manifest-based bundle packaging for Emscripten builds

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