PyeLink

A modern Python wrapper for SR Research EyeLink eye trackers with multi-backend display support (pygame, PsychoPy, pyglet).

PyeLink provides programmatic control over the full EyeLink workflow: connection management, calibration and validation with configurable parameters (number of points, calibration area proportion, target appearance), recording with real-time data access, and direct access to any EyeLink command for advanced configurations not exposed through the high-level API.

For full documentation, see pyelink.readthedocs.io.

Features

• Multi-backend display: pygame (recommended), PsychoPy, or pyglet
• Configurable calibration: 3/5/9/13-point calibration, adjustable calibration area proportion, custom target appearance (ABC/circle/image)
• Full programmatic control: configure every tracker parameter from Python, including calibration area, sample rate, heuristic filtering, and screen geometry
• Direct command access: send any EyeLink command via tracker.send_command() for advanced configurations (same syntax as Host PC INI files)
• Real-time data access: gaze samples, fixation/saccade/blink events, with optional ring buffering
• Validated settings: Pydantic-based configuration with runtime type checking and helpful error messages
• Graceful shutdown: Ctrl+C at any point (including during calibration) automatically stops recording, saves data, and disconnects

Installation

You must specify a backend when installing pyelink. A simple pip install pyelink will NOT work because pyelink requires one of three mutually exclusive display backends (pygame, psychopy, or pyglet).

Choose ONE backend:

# For Pygame users
pip install pyelink[pygame]

# For PsychoPy users (Python < 3.12 only)
pip install pyelink[psychopy]

# For Pyglet users (pyglet 2.0+)
pip install pyelink[pyglet]

You'll also need to install the EyeLink Developers Kit (native C libraries) from: https://www.sr-research.com/support/thread-13.html

Then install pylink separately from SR Research:

uv pip install --extra-index-url https://pypi.sr-support.com sr-research-pylink

Note: This codebase has been tested on macOS ARM (Apple Silicon) only.

⚠️ Backend Compatibility Warning

You CANNOT install both psychopy and pyglet backends together.

Why? PsychoPy pins pyglet==1.4.11 (from 2017) as a dependency, while the modern pyglet backend requires pyglet>=2.0.0. These versions are incompatible.

Solution: Choose ONE backend:

• Pygame (recommended): Works everywhere, no conflicts
• PsychoPy: Use if you need PsychoPy features, but cannot use pyglet 2.0+
• Pyglet: Use if you want modern pyglet (2.0+) but don't need PsychoPy

Platform-Specific Notes

macOS:

• PyAudio requires PortAudio. Install it first:

brew install portaudio

macOS ARM (Apple Silicon) — sr-research-pylink:

SR Research does not publish ARM-native wheels for sr-research-pylink. The package must be installed separately using uv pip install --extra-index-url (as shown above) rather than through uv sync or uv run. This is because uv sync resolves dependencies across all Python versions specified by requires-python, and SR Research's PyPI server does not have wheels for every version. Using uv pip install resolves only for the current Python and works correctly.

Quick Start

import pyelink as el

# Configure tracker with backend
settings = el.Settings(
    backend="pygame",  # or 'psychopy', 'pyglet'
    fullscreen=True,
    screen_res=(1920, 1080),  # must match your display
    screen_width=530.0,  # physical display width in mm
    screen_height=300.0,  # physical display height in mm
    screen_distance_top_bottom=(600.0, 640.0),  # eye-to-screen edges in mm
    filename="mydata",
    filepath="./data/",
)

# Tracker creates and owns the window
tracker = el.EyeLink(settings)

# Calibrate (optionally record samples during calibration)
tracker.calibrate(record_samples=True)

# Option A: Direct window access for custom drawing
tracker.window.fill((128, 128, 128))  # pygame example
# ... backend-specific drawing ...
tracker.flip()

# Option B: Helper methods for common patterns
tracker.show_message("Press SPACE to begin")
tracker.wait_for_key("space")

# Run your experiment
tracker.start_recording()
# ... show stimuli, collect data ...
tracker.stop_recording()

# Clean up (closes window and saves EDF automatically)
tracker.end_experiment()

Advanced Configuration

All tracker parameters are configurable through the Settings class:

settings = el.Settings(
    backend="pygame",
    n_cal_targets=13,  # 13-point calibration for large displays
    calibration_area_proportion=(0.44, 0.415),  # reduce calibration area for close viewing
    calibration_corner_scaling=0.8,  # pull corner targets inward
    sample_rate=1000,  # 250, 500, 1000, or 2000 Hz
    illumination_power=3,  # reduce IR power (1=100%, 2=75%, 3=50%)
    # ... 50+ configurable parameters
)

For commands not exposed through Settings, use direct tracker control:

tracker.send_command("select_parser_configuration 0")
tracker.send_command("file_sample_data = LEFT,RIGHT,GAZE,GAZERES,AREA,HREF,PUPIL,STATUS")

Development

For development with different backends:

# PsychoPy backend
uv pip uninstall pyelink && uv pip install -e ".[psychopy]" && uv pip install --extra-index-url https://pypi.sr-support.com sr-research-pylink

# Pygame backend
uv pip uninstall pyelink && uv pip install -e ".[pygame]" && uv pip install --extra-index-url https://pypi.sr-support.com sr-research-pylink

# Pyglet backend
uv pip uninstall pyelink && uv pip install -e ".[pyglet]" && uv pip install --extra-index-url https://pypi.sr-support.com sr-research-pylink

Attribution

This package is based on code originally developed by:

• Marcus Nyström (Lund University Humanities Lab, Lund, Sweden)

  • Email: marcus.nystrom@humlab.lu.se

• pylinkwrapper by Nick DiQuattro

  • Repository: https://github.com/ndiquattro/pylinkwrapper
  • Core EyeLink functionality and wrapper architecture

Citation

Cite as:

Salari, M., Nyström, M., Niehorster, D. C., & Bednarik, R. (2026).
PyeLink and SyeLink: Open-source Python tools for low-level EyeLink experiment control and data parsing.
In Proceedings of the 2026 Eye Tracking Research & Applications (ETRA 2026) Late-Breaking Work. ACM.
DOI: 10.1145/3797246.3805844

Acknowledgments

This project has received funding from the European Union's Horizon Europe research and innovation funding program under grant agreement No 101072410, Eyes4ICU project.