EyeLink 1000 Plus

Integration guide for using the SR Research EyeLink 1000 Plus eye tracker with HyperStudy experiments through the HyperStudy Bridge.

Overview

The EyeLink 1000 Plus is a high-speed video-based eye tracker manufactured by SR Research. It connects to HyperStudy via the Bridge application, which communicates with the tracker through SR Research's eyelink_core C library. The Bridge loads this library at runtime, so the EyeLink SDK must be installed on the machine running the Bridge — but the Bridge application itself installs and runs without the SDK present.

Signal Flow

HyperStudy Web App → HyperStudy Bridge → eyelink_core SDK → EyeLink Host PC → EyeLink Tracker

Features

• High-Speed Gaze Tracking: Up to 2000 Hz sampling rate (model-dependent)
• Real-Time Gaze Streaming: Live gaze position, pupil size, and angular resolution forwarded to HyperStudy
• EDF Recording: Full-fidelity data recording on the EyeLink Host PC
• Event Markers: Timestamped messages written to the EDF file for synchronization
• Calibration: Full calibration/validation loop driven from the HyperStudy frontend
• Runtime SDK Detection: Bridge auto-detects the SDK — no special build or feature flags needed

Prerequisites

Hardware

• EyeLink 1000 Plus eye tracker (or compatible EyeLink model)
• EyeLink Host PC (the dedicated computer that comes with the tracker)
• Ethernet connection between the Host PC and the Display PC (the machine running HyperStudy Bridge)
• The Display PC's Ethernet interface configured to the EyeLink subnet (typically 100.1.1.2, subnet 255.255.255.0)

Software

• HyperStudy Bridge v0.8.22 or later
• EyeLink Developers Kit (see installation instructions below)

Installing the EyeLink Developers Kit

The EyeLink Developers Kit provides the eyelink_core runtime library that the Bridge needs to communicate with the tracker. It is proprietary software from SR Research and cannot be bundled with the Bridge — you must install it separately.

warning

The EyeLink Developers Kit requires a free SR Research support account. You will need to register before downloading.

Step 1: Create an SR Research Support Account

1. Go to www.sr-research.com/support
2. Click Register and create a free account
3. Verify your email address

Step 2: Download the Developers Kit

1. Log in to the SR Research support portal
2. Navigate to Downloads → EyeLink Developers Kit
3. Download the installer for your operating system:
   • macOS: EyeLink_Developers_Kit_macOS_<version>.dmg
   • Windows: EyeLink_Developers_Kit_Windows_<version>.exe
   • Linux: eyelink-display-software_<version>.deb (Ubuntu/Debian)

Step 3: Install

macOS

1. Open the downloaded .dmg file
2. Run the installer package (.pkg)
3. Follow the installation prompts — the default location installs the framework to /Library/Frameworks/eyelink_core.framework/
4. No reboot required

To verify the installation:

# Check that the framework exists
ls /Library/Frameworks/eyelink_core.framework/eyelink_core

Windows

1. Run the downloaded .exe installer
2. Follow the installation wizard with default settings
3. The SDK installs to C:\Program Files\SR Research\EyeLink\ by default
4. The installer adds the library directory to the system PATH

To verify:

# Check that the DLL exists
dir "C:\Program Files\SR Research\EyeLink\Libs\x64\eyelink_core.dll"

Linux (Ubuntu/Debian)

1. Install the package:

sudo dpkg -i eyelink-display-software_<version>.deb
sudo apt-get install -f  # Fix any dependency issues

2. The shared library installs to /usr/lib/

To verify:

# Check that the shared library exists
ldconfig -p | grep eyelink_core

What If the SDK Is Not Installed?

The Bridge application starts and runs normally without the SDK. All non-EyeLink devices (TTL, Kernel, Pupil, LSL) work as usual. If you attempt an EyeLink operation without the SDK installed, the Bridge returns a clear error message:

EyeLink SDK not found. Install the SR Research EyeLink Developers Kit from www.sr-research.com/support

Configuration

Network Setup

The EyeLink Host PC and Display PC communicate over a dedicated Ethernet connection:

Setting	Host PC (EyeLink default)	Display PC (your machine)
IP Address	100.1.1.1	100.1.1.2
Subnet Mask	255.255.255.0	255.255.255.0

Configure the Display PC's Ethernet adapter to use 100.1.1.2 with subnet 255.255.255.0. This is typically a dedicated Ethernet port — your regular network/WiFi connection remains unchanged.

Bridge Configuration

In the HyperStudy Bridge GUI, click the gear icon on the EyeLink device card to configure:

Setting	Default	Description
IP Address	100.1.1.1	IP address of the EyeLink Host PC
Sample Rate	1000 Hz	Gaze data sampling rate (250, 500, 1000, or 2000 Hz)
Display Width	1920 px	Participant display width in pixels
Display Height	1080 px	Participant display height in pixels

The display dimensions are sent to the tracker so gaze coordinates are reported in the correct pixel space.

Usage

Basic Workflow

1. Power on the EyeLink tracker and Host PC
2. Verify network — ensure the Display PC can reach the Host PC:

   ping 100.1.1.1

3. Launch HyperStudy Bridge on the Display PC
4. Connect to the EyeLink via the Bridge GUI or WebSocket command
5. Calibrate using the Bridge's calibration interface
6. Start recording to begin writing data to the EDF file
7. Run your experiment — send event markers from HyperStudy for synchronization
8. Stop recording and disconnect when finished
9. Retrieve the EDF file from the Host PC for analysis

Calibration

Calibration is initiated from the Bridge and renders calibration targets in the HyperStudy frontend. During calibration:

• The tracker presents targets at known screen positions
• The participant fixates on each target
• Press Accept (Enter) to accept a calibration point
• Press Cancel (Escape) to abort calibration
• After calibration, the tracker automatically runs validation

Event Markers

Send timestamped messages to the EDF file for synchronization with your experiment timeline:

// From HyperStudy web app via WebSocket
{
  "type": "command",
  "device": "eyelink",
  "action": "send_eyelink_message",
  "payload": { "message": "TRIAL_START 1" }
}

These messages appear in the EDF file with the tracker's own timestamp, providing precise synchronization between your experiment events and the eye tracking data.

WebSocket Commands

Action	Description
connect_eyelink	Connect to the tracker at the configured IP
disconnect_eyelink	Disconnect from the tracker
start_eyelink_recording	Start EDF recording (file + link samples/events)
stop_eyelink_recording	Stop EDF recording
send_eyelink_message	Write a timestamped marker to the EDF file
calibrate_eyelink	Start the calibration/validation loop
calibrate_eyelink_key	Send accept/cancel key during calibration
connect_eyelink_gaze	Start real-time gaze data streaming
disconnect_eyelink_gaze	Stop gaze data streaming
eyelink_status	Query current connection and recording status

Troubleshooting

"EyeLink SDK not found"

The eyelink_core library is not installed or not in the expected location.

• macOS: Verify /Library/Frameworks/eyelink_core.framework/eyelink_core exists
• Windows: Verify eyelink_core.dll is in the system PATH or C:\Program Files\SR Research\EyeLink\Libs\x64\
• Linux: Run ldconfig -p | grep eyelink_core to check

If you just installed the SDK, try restarting the Bridge application.

Connection Failed

• Verify the Host PC is powered on and the EyeLink software is running
• Check the Ethernet cable between Display PC and Host PC
• Confirm the Display PC's Ethernet interface is configured to 100.1.1.2/24
• Try ping 100.1.1.1 from the Display PC
• Ensure no firewall is blocking traffic on the 100.1.1.0/24 subnet

Calibration Not Responding

• Make sure the participant's eye is visible in the camera view on the Host PC
• Check that the tracker is in "Record" or "Setup" mode on the Host PC
• Verify the display dimensions in Bridge config match the actual participant monitor

Gaze Data Not Streaming

• Recording must be started before gaze streaming will produce data
• Check that link_sample_data is configured (the Bridge sets this automatically on connect)
• Verify the sample rate setting matches the tracker's capabilities

Resources

• SR Research Support: www.sr-research.com/support — SDK downloads, manuals, and forums
• EyeLink Programmer's Guide: Included with the EyeLink Developers Kit installation
• HyperStudy Bridge: GitHub Repository