EyeLink II User Manual

EyeLink® II Head Fixed Eye Tracker

User Manual

Version 2.12

EyeLink is a registered trademark of SR Research Ltd, Mississauga, Canada.

Table of Contents

Introduction ...........................................................................................................1

1.1 Supporting Documents......................................................................... 1

1.2 EyeLink® II System Overview ................................................................ 2

1.3 EyeLink II System Configuration .......................................................... 2

1.3.1 EyeLink II Host PC ........................................................................................3

1.3.2 EyeLink II Display PC.................................................................................... 3

1.3.3 EyeLink II PCI Card....................................................................................... 5

1.4 System Specifications........................................................................... 5

1.4.1 Tracking Modes............................................................................................. 5

1.4.2 Operational / Functional Specifications ......................................................... 5

1.4.3 Physical Specifications.................................................................................. 6

2. EyeLink II Tracker Application Operation ........................................................... 8

2.1 Starting the Host Tracker ..................................................................... 8

2.2 Modes of Operation .............................................................................. 8

2.3 EyeLink II Tracker Application Navigation............................................. 9

2.3.1 Offline Screen.............................................................................................. 10

2.3.2 Camera Setup Screen ................................................................................. 12

2.3.3 Set Options Screen .....................................................................................16

2.3.4 Calibration Screen....................................................................................... 21

2.3.5 Validation Screen ........................................................................................23

2.3.6 Drift Correct Screen..................................................................................... 25

2.3.7 Output Screen .............................................................................................27

2.3.8 Record Screen............................................................................................. 29

2.4 Status Panel....................................................................................... 31

2.5 Mouse Simulation Mode ..................................................................... 32

2.6 Configuration Files and Experiment Directories .................................. 32

2.7 Analog Data Types.............................................................................. 33

3. An EyeLink II Tutorial: Running an Experiment ............................................... 35

3.1 The Camera Setup Screen .................................................................. 36

3.2 Adjusting Eye Camera Position........................................................... 37

3.3 Setting Pupil Threshold ...................................................................... 40

Calibration......................................................................................... 42

3.4

3.5 Validation .......................................................................................... 47

3.6 Recording Gaze Position ..................................................................... 49

3.7 Drift Correction .................................................................................. 49

3.8 Exiting EyeLink II............................................................................... 51

3.9 EyeLink II Setup Summary................................................................. 51

3.10 Experiment Practice ........................................................................ 52

3.11 Next Steps: Other Sample Experiments............................................ 52

4. Data Files .............................................................................................................56

4.1 File Contents...................................................................................... 56

4.2 Recording EDF Files........................................................................... 57

4.2.1 Recording from the EyeLink II Host PC....................................................... 57

4.2.2 Recording from the EyeLink API .................................................................57

4.3 The EyeLink On-Line Parser ............................................................... 57

4.3.1 Parser Operation ......................................................................................... 57

4.3.2 Parser Limitations........................................................................................ 58

4.3.3 EyeLink Parser Configuration...................................................................... 58

4.3.4 Parser Data Type ........................................................................................59

4.3.5 Saccadic Thresholds ................................................................................... 59

4.3.6 Pursuit Thresholds ...................................................................................... 60

4.3.7 Fixation Updates ......................................................................................... 60

4.3.8 Other Parameters ........................................................................................ 61

4.3.9 Sample Configurations ................................................................................ 61

4.4 File Data Types .................................................................................. 62

4.4.1 Samples....................................................................................................... 62

4.4.2 Position Data ............................................................................................... 63

4.4.3 Pupil Size Data............................................................................................ 66

4.4.4 Button Data.................................................................................................. 66

4.5 Events ............................................................................................... 66

4.5.1 Messages .................................................................................................... 67

4.5.2 Buttons ........................................................................................................67

4.5.3 Eye Movement Events................................................................................. 67

4.6 Setting File Contents .......................................................................... 71

4.6.1 Sample Data................................................................................................ 72

Event Data................................................................................................... 72

4.6.2

4.6.3 Event Types ................................................................................................ 73

4.7 EDF File Utilities................................................................................ 73

4.7.1 EDFSCAN ................................................................................................... 74

4.8 Using ASC Files.................................................................................. 74

4.8.1 EDF2ASC .................................................................................................... 75

4.8.2 Translator Options....................................................................................... 75

4.9 The ASC File Format .......................................................................... 78

4.9.1 ASC File Structure....................................................................................... 78

4.9.2 Sample Line Format .................................................................................... 79

4.9.3 Event Line Formats .....................................................................................82

4.9.4 Data-Specification Lines.............................................................................. 84

4.10 Processing ASC Files ....................................................................... 86

4.11 An ASC File Processing Program ...................................................... 86

5. Troubleshooting .................................................................................................. 88

Problem: Eye Camera Images are blank or blue.......................................... 88

Problem: LED Warning on Host PC startup ................................................. 88

Problem: Host PC Warning Message or Image Loss ...................................... 88

6. System Care......................................................................................................... 90

6.1 Maintenance ...................................................................................... 90

6.2 Storage and Transportation ................................................................ 91

7. Important Information ......................................................................................... 93

7.1 Safety ................................................................................................ 93

7.1.1 Electrical Isolation Safety ............................................................................ 93

7.1.2 Eye Illumination Safety................................................................................ 93

7.2 Limited Hardware Warranty ............................................................... 94

7.3 Limited Software Warranty ................................................................. 95

7.4 Copyrights / Trademarks ................................................................... 95

8. Appendix A: Using the EyeLink II Analog and Digital Output Card................ 96

8.1 Analog Data Quality ........................................................................... 96

8.2 Setting up the EyeLink II Analog Card ................................................ 97

8.2.1 Installing Analog Output Hardware.............................................................. 97

8.2.2 Connections to Analog Card........................................................................ 97

8.2.3 Noise and Filtering ...................................................................................... 97

Digital Inputs and Outputs................................................................. 97

8.3

8.3.1 Analog Data Output Assignments ...............................................................98

8.3.2 Analog Data Types and Ranges.................................................................. 99

8.3.3 Scaling of Analog Position Data .................................................................. 99

8.4 Pupil Size Data................................................................................. 100

8.5 Time base and Data Strobe............................................................... 100

8.5.1 Strobe Data Input ......................................................................................101

8.5.2 Over sampling and Toggle Strobe............................................................. 101

List of Figures

Figure

Figure 2-1: Screen Overview of EyeLink II Tracker Program............................. 9

Figure 2-2: EyeLinkII Offline Screen............................................................... 10

Figure 2-3: EyeLink II Camera Setup Screen.................................................. 12

Figure 2-4: EyeLinkII Set Option Screen ....................................................... 16

Figure 2-5: EyeLink II Calibration Screen....................................................... 21

Figure 2-6: EyeLinkII Validation Screen ......................................................... 23

Figure 2-7: EyeLinkII Drift Correction Screen................................................. 25

Figure 2-8: EyeLinkII Output Screen.............................................................. 27

Figure 2-9: EyeLinkII Record Screen .............................................................. 29

Figure 2-10 EyeLink II Status Panel............................................................... 31

Figure 3-1: Example Camera Setup Screen before Camera Setup. .................. 36

Figure 3-2: Size and Vertical Eye Camera Adjustments ................................. 38

Figure 3-3: Horizontal Adjustments of Eye Camera ....................................... 39

Figure 3-4: Focusing the Eye Camera ........................................................... 40

Figure 3-5: Symptoms of Poor Pupil Threshold .............................................. 41

1-1: Typical EyeLink II System Configuration ........................................ 2

Figure 3-6: Corner Effects Seen with Head Rotation ...................................... 42

Figure 3-7. Calibration Grid following a Good and Poor Calibration ................ 45

Figure 3-8. Performing an online drift correction with mouse click ................. 51

Read instructions before use.

Type BF equipment (applied parts): Metal parts connected to chassis of computer may contact user. Compliance with 601-1 medical equipment standards requires use of a medical grade power supply. Entela Safety Mark: Compliance of this product with UL 2601-1, CSA C22.2 N0.601.1 and IEC 60601-1 is certified by Entela, an independent testing body.

CONTACT ADDRESS

SR Research Ltd. 5516 Main St., Osgoode, Ontario, Canada K0A 2W0 Fax: 416-352-5376 Phone: 613-826-2958 Toll Free Phone: 1-866-821-0731 (North America Only)

http://www.eyelinkinfo.com/

1. Introduction

This section introduces the EyeLink II system, technical capabilities, and supporting documentation.

IMPORTANT: Be sure you have read and agree to the end user license agreement provided in section 7.2 of this document before using the EyeLink II system.

NOTE: Please be sure to check http://www.eyelinkinfo.com/news.php for product and documentation updates as they become available.

1.1 Supporting Documents

This document contains information on using the EyeLink II system; host PC application, subject setup and calibration, and the basics of running an experiment. Information on system safety, maintenance, and storage is also provided. The Appendix A of the current manual explains the use of analog output and digital inputs and outputs via a DT334 card, if purchased. Additional documents are also available:

A. EyeLink II Installation Guide

layout and environmental considerations as well as the process followed to install the EyeLink II hardware and software on both the Host and Display computers.

B. Windows Programmers Guide – Provides suggestions on how to program

experiments with EyeLink II in Windows, including review of all sample experiments provided for Windows. Document also details the EyeLink II Windows API.

EyeLink Data Viewer User’s Manual – Introduces an optional Data analysis tool, EyeLink Data Viewer, which allows the displaying, filtering, and outputting of EyeLink I and EyeLink II EDF data.

D. EyeLink II Scene Camera User Manual – Provides introduction to an

optional tool, EyeLink II Scene Camera, with which the users can track gaze position on a real world scene video being captured from a head mounted scene camera.

E. EyeLink II Gaze Overlay User Manual.

works with the EyeLink II system to generate a real-time gaze overlay graphic on an S-Video source. This option is often used to provide a gaze overlay onto a dynamic moving scene such as non-static website, AVI file, or DVD movie, etc. This PAL/NTSC composite or S-Video signal is then typically saved onto a VCR or DVD recorder for analysis.

– Describes a standard EyeLink II system

The optional Gaze Overlay device

1.2 EyeLink® II System Overview

Video-based eye tracking systems have long been acknowledged as the simplest to set up and operate. However, these systems also had a reputation for low data rates, poor spatial resolution, high noise, and frequent loss of data. The EyeLink technology changed all of this with custom-built high-speed cameras and hyperacuity image processing. EyeLink II has the highest resolution (noiselimited at <0.01°) and fastest data rate (500 samples per second) of any other video-based eye tracker today. This exceptional data quality results in very low velocity noise, making the EyeLink II ideal for saccade analysis and smooth pursuit studies. On-line gaze position data is available with delays as low as 3 milliseconds, making the system ideal for gaze-contingent display applications. In addition, on-line data parsing occurs, making eye events such as saccade, fixation, and blink available within 25 ms to the display computer.

The EyeLink II system consists of two miniature cameras which are mounted onto a head restraint. No mirrors are used in the EyeLink II system, making it very robust and easy to set up. Two eye cameras allow binocular eye tracking or easy selection of the subject's dominant eye without the mechanical reconfiguration required by most eye trackers. Each camera has built-in illuminators, digitally corrected for even lighting of the entire field of view. Together with digital compensation for changes in ambient lighting, this results in exceptionally stable pupil acquisition.

SR Research is committed to developing EyeLink-based applications to support most eye-tracking research applications, and will make available softwaredevelopment tools for using the EyeLink II data-link and file formats. We will keep you informed of improvements in documentation and availability of these tools.

1.3 EyeLink II System Configuration

Figure 1-1: Typical EyeLink II System Configuration

1.3.1 EyeLink II Host PC

The EyeLink II Host PC performs real-time eye tracking at 250 or 500 samples per second, while also computing true gaze position on the subject display. Online detection analysis of eye-motion events such as saccades and fixations is also performed. This data can be stored in a data file on the Host PC, sent through the Ethernet link to the Display PC, or output as analog signals (if the analog/digital I/O card is installed). From the Host PC, the operator performs subject setup, monitors performance, and can control applications running on the Display PC. The Host PC has these key attributes:

• Hosts EyeLink II high-speed eye tracking card, optional analog

output/digital input card.

• Runs a special operating system to host the EyeLink II operator

software. Your original operating system (such as Windows XP) is still available, if disk the partitioning utility (included with self-installation kit) is used during installation.

• Functions either as standalone tracker or connected to display computer

through 10BASE-T Ethernet cable.

• In standalone configuration, data output is to hard disk or through

optional analog output card.

• Response box or game pad connected by a USB port.

• Keyboard, display, and pointing device are used to control tracker or as

remote keyboard for applications on display computer.

• EyeLink II software integrates all needed eye tracking functionality,

including subject setup, calibration, real-time data through Ethernet link or optional analog output card, and writing of data to hard disk.

• Display has real-time feedback of eye data during calibration or

recording, freeing display computer's monitor for calibration target and stimulus presentation.

• Data File viewing and conversion tools

1.3.2 EyeLink II Display PC

The EyeLink II Display PC provides displays for experiments, and calibration targets during eye-tracker calibrations. On-line eye and gaze position can be received from the EyeLink Operator PC via the Ethernet link. Sample

applications, C source code, and instructions for creating experimental applications are provided in the EyeLink II Windows developer kit. DOS and MAC API’s are also available on request. The Display PC has the following key attributes:

• Runs experiment application software for control of EyeLink II tracker and

stimulus presentation using EyeLink II API, allowing development of extensive experimental paradigms.

• Display Applications can configure and control the EyeLink tracker, and

have access to real-time data including gaze position, response box button presses, and keyboard.

• Applications need only support display generation and control of the

experiment sequence, and should rely on the tracker for creating the data file and reading the response box. This makes millisecond-accurate display timing possible, even under Windows.

• 4 infrared markers (for head tracking) mounted on corners of display.

• Data File viewing and conversion tools

1.3.3 EyeLink II PCI Card

The EyeLink II PCI card performs the powerful image processing required to achieve the high temporal and spatial resolution capable with the system. The PCI card is hosted in the Host PC and has connectors for:

• EyeLink II headband on a 5-meter cable.

• Head tracking markers on a 7-meter cable.

• Ethernet cable for Display PC connection.

1.4 System Specifications

1.4.1 Tracking Modes

Mode Sample Rate Average Delay

(Filter Off/On)

Pupil Only

250 or 500Hz 3 ms / 5 ms / 7 ms < 0.01° Affected by headband

1.4.2 Operational / Functional Specifications

Image Processing

Pupil Tracking

Resolution (Gaze)

Velocity Noise

Pupil Size Resolution

Eye Tracking Range

Gaze Tracking Range

Built-in calibration, validation

Fully Digital

Hyper acuity

<0.005°

<3° average

0.1% of diameter

±30° horizontal, ±20° vertical in pupil only mode.

±20° horizontal, ±18° vertical

Calibration / Validation using Pupil

Noise (RMS) Stability

slip and vibration

Operating Environment

Data File

EDF File and Link Data Types

Tolerates significant indirect IR

EDF

Eye position, HREF position, gaze position, pupil size, buttons, messages, digital inputs

On-Line Eye Movement Analysis

Saccades, fixations, blinks, fixation updates

Real-Time Operator Feedback

1.4.3 Physical Specifications

EyeLink II Card

Camera cable length

Eye camera distance

Binocular Tracking

Eye Illumination

Ethernet Link

Response box support

Analog output

Digital Control

Host Operating system

Eye position cursor during calibration, validation, and recording. Camera images and tracking status.

Half-length PCI (6.8"/176mm) long by 4.2" (107mm) high.

4.2 meters

40 to 80 mm

Standard

925 nm IR, IEC-825 Class 1, <1.2 mW/cm2

TCP/IP or raw, 10BASE-T, built into EyeLink II card

USB or digital

Optional PCI card

Configurable

ROMDOS operating system

Display Operating system API

Classification

Power Supply Requirements

Operating conditions

Storage conditions

EyeLink II Card Power Requirements

Electromagnetic compatibility and immunity

Windows (95, 98, NT, 2000, XP), MS-DOS, Macintosh.

Class II (grounding optional), type BF (conductive path from computer chassis to metal parts on the headband) Powered from host computer power supply, 160W or greater power supply recommended. Medical-grade power supply is required for 601-1 compliance. 15°C to 35°C, 20%-80% humidity (noncondensing), ambient pressure 101 kPa.

-10°C to 40°C, 10%-90% humidity (noncondensing). Allow to warm to room temperature before unpacking or use after storage at temperatures below 10°C. +5V (2A), +12V (0.8A), -12V (0.2A), 22 watts

FCC Part 15, Subpart B: Class A unintentional radiators (see statement below) CISPR 11:1997 and EN55011:1998 -- Class A, Group 1 ISM (Industrial, Scientific, and Medical) Equipment EN 60601-1-2:1993 – Part 1: General Requirements for Safety-Collateral Standard Electromagnetic Compatibility-Requirements and Tests.

NOTE: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at the users’ expense.

WARNING: Changes or modifications not expressly approved by SR Research Ltd. could void the user’s warranty and authority to operate the equipment.

2. EyeLink II Tracker Application Operation

2.1 Starting the Host Tracker

To start the EyeLink II Host Tracker follow these simple steps:

a) Start your Host PC

b) If your system was installed with BootMagic, select the EyeLinkII

partition

c) If the EyeLink II Tracker program does not automatically start, type the

following at the command prompt:

cd eyelink2\exe [ENTER]

eyelink2.exe [ENTER]

The EyeLink II Tracker application should start and display the Offline tracker screen.

2.2 Modes of Operation

The EyeLink II is a multipurpose, high resolution, real-time processing system. It is designed to be used in 2 different primary operation modes:

Link: In this mode, the eye tracker is partially controlled by the Display PC via the Ethernet link. The degree of Display PC control is dependent only on the display application itself. It is possible to have full control of the tracker via the Display PC; however this also requires the most display application programming. A common scenario is to have the application on the display PC control the eye tracker to start subject setup and calibration, while the operator uses the EyeLink II Host PC's keyboard to remotely control the application, perform drift correction, and handle problems if they occur.

Standalone: In this mode, the eye tracker is an independent system, controlled by the operator by the Host PC tracker interface and keyboard. The Host PC is still connected to a display-generating computer for the purpose of displaying calibration targets only. There are 2 possible data output modes when running the EyeLink II as a standalone system. These output modes are not exclusive and include:

a) Analog output in analog format. Analog output options are configurable via the “Set Options” screen and in the analog.ini initialization file.

. Using the optional analog output card, data is available

b) File Output This can be converted to an ACSII file format using the edf2asc conversion utility. File output options are configurable via the “Set Options” screen.

2.3 EyeLink II Tracker Application Navigation

The EyeLink II tracker interface consists of a set of setup and monitoring screens, which may be navigated by means of the host PC mouse, key shortcuts, or from the Display PC application via link commands.

. Eye data is available in the EyeLink II EDF file format.

Figure 2-1: Screen Overview of EyeLink II Tracker Program

Each of the modes shown in the diagram above has a special purpose. Where possible, each screen has a distinctive appearance as shown in the figure. Screens with gray bars contain menus of key options for navigation and setup. Other screens have a key-navigation bar at the top of the screen and a status bar at the bottom. Arrows represent the navigations possible by keys: any mode is accessible by link control. Note the central role of the Setup menu: it serves as the mode control during subject setup.

The functions of each mode and the main access keys to other modes are

summarized below. Pressing the on screen Help button or hitting the F1 key will open a screen sensitive Help menu listing all available key shortcuts for that screen. From any screen, the key combination ‘CTRL+ALT+Q’ will exit the EyeLink tracker program.

2.3.1 Offline Screen

Ethernet Connection Status

Screen

avigation

Camera view with threshold status

Figure 2-2: EyeLinkII Offline Screen

2.3.1.1 Purpose

The off-line mode is the default start-up screen for EyeLink II. The main secondary screens can be accessed via the navigation buttons on the left hand side of the screen.

2.3.1.2 Main Functions

Press to go to the camera setup screen. Keys: ENTER = Camera Setup Select Output to go to the output

screen, from which you can start a manual recording session. Keys: O = go to Output screen

Select Set Options to go to the EyeLink II options screen, where a variety of system options and settings can be configured. Note that any value on this screen can be programmatically overridden by the API during experiment setup. Keys: S = go to Set options

Select Exit EyeLink to end the EyeLink II program. Keys: Ctrl + Alt + Q = Exit EyeLink Press Help (F1) to access the online help page for Camera Setup. All available key shortcuts are also listed on the Help screen. Keys: F1 = open Help screen

2.3.1.3 Key Shortcuts

ENTER Press to enter camera setup O Press to go to the Output screen S Press to go to the Set Options screen Ctrl + Alt + Q Press to exit the EyeLink program F1 Press to view the Help screen, in the

help screen there is a brief overview of the role of this page and the key functions for it.

2.3.2 Camera Setup Screen

Image Display Attributes

Tracking Mode

Figure

Camera Select and Status

2-3: EyeLink II Camera Setup Screen

Selected eye(s) to track

2.3.2.1 Purpose

This is the central screen for most EyeLink II setup functions. From this screen the eye and head tracking cameras can be set up, and their images can be thresholded. Eye(s) to be tracked, tracking mode and options can also be set. Calibration, Validation, and Drift correction can also be performed from this screen.

2.3.2.2 Main Functions

Press Auto Threshold to threshold the selected camera image. In most cases auto thresholding will set the correct image threshold for the camera. Keys: A = Auto threshold selected image

Use the arrow buttons to manually increase or decrease the selected camera’s pupil threshold. Keys: ⇑ and ⇓ = increase and decrease threshold

Select the sampling rate for recording. Here 250 Hz is selected. Note that in Pupil-CR mode, 500Hz is not available. Keys: F = toggles sampling Frequency selection

Toggles display of crosshair in eye camera images. Keys: X = toggle crosshair display

Toggles display of threshold coloring in eye camera images. Keys: T = toggle threshold coloring display

Select to present the camera display image on the Display Monitor.

To select the camera to display as a large image click on the desired image thumbnail. The selected image thumbnail has a heavy border around it. Here the Right Eye camera is selected. Image thresholds and status are indicated below each thumbnail. Keys: ⇐ and ⇒ to move left or right on image row

Select the eye(s) to track during recording. Here the Right eye is selected. Press the “Lock Tracked Eye” button to lock the current selection on the Display PC. Keys: R = select Right Eye L = select Left Eye B = select Both Eyes

Press Exit Setup to go to the screen that was available prior to accessing the Camera Setup window. Keys: ESC = exit camera setup

Press Offline to be returned to the EyeLink II offline screen. Keys: ESC = go to Offline screen

Select Output / Record to go to the output screen, from which you can start a manual recording session. This button is usually only access when using the EyeLink II in standalone mode. Keys: O = go to Output screen

Press Help (F1) to access the online help page for Camera Setup. All available key shortcuts are also listed on the Help screen. Keys: F1 = open Help screen

Select Calibration to go to the Calibration screen. After setting up the eye cameras and thresholding, you need to Calibrate the system.

Keys: C = go to Calibrate screen

Select Validation to be taken to the Validation Screen. Validation allows you to get a sense of the gaze position accuracy of your Calibration. Validation should always be run after Calibration. Keys: V = go to Validate screen

Select Drift Correction to go to the Drift Correction Screen. Drift Correction can be performed before and during an experiment; allowing gaze position to be realigned if headband slippage or significant pupil size change has increased gaze calculation error. Keys: D = go to Drift correction screen

2.3.2.3 Key Shortcuts

Key Function

⇐ and ⇒

B Select both eyes for recording F Toggle sampling frequency selection A Auto threshold selected image X Toggle crosshair display T Toggle threshold coloring display ⇑ and ⇓ C Go to the Calibration screen V Go to the Validate screen D Go to the Drift correction screen O Go to the Output screen S Go to Set Options page F1 Open the Help dialog, in the help screen there is a brief

ESC Go to the Offline screen or exit camera setup

Select between left eye camera, head camera and right eye camera. Select Right eye for recording

Select left eye for recording

Increase and decrease threshold

overview of the role of this page and the key functions for it

2.3.3 Set Options Screen

EyeLink Data File component

Calibration and Validation options

Figure 2-4: EyeLinkII Set Option Screen

Data and system sensitivity

Analog Output selection

EyeLink Data File component

2.3.3.1 Purpose

The Set Options screen allows many EyeLink II tracker options to be configured manually. This is useful when doing manual recording sessions that are not driven by a Display PC using the EyeLink II API. When using the EyeLink II API to drive stimulus presentation, these settings are normally set by the Display application via a set of API calls.

The Default Settings should be sufficient for many tracking applications.

2.3.3.2 Main Functions

Select the calibration type for recording. Here a ninepoint calibration is selected (New: "HV13", 13-point calibration, which works best with displays with large angular extent). Keys: C=toggles Calibration Set the time delay for Calibration and Validation if auto trigger is selected. Keys: P = toggles Pacing Randomize the calibration and validation fixation dot sequence selected. Keys: R = Randomize Order Redisplay the first calibration or validation fixation dot. Keys: I = Repeat First Point Select Force Manual Accept to manually accept each calibration and validation fixation point. Select Lock Eye After Cal to lock the recording eye on the Display PC keyboard if performing a monocular recording. In Mouse Simulation mode the Host PC mouse simulates eye movement and can be used for experiment debugging purposes. Keys: M = toggles Mouse Simulation modes Record the participants’ eye area or diameter in pixels. The area is recorded in image pixels. The Diameter is recorded in millimeters. Keys: S = toggles Pupil size Area or Diameter Select Eye Event Data to record the Gaze or HREF of the participant.

Keys: E = toggles Gaze and HREF settings Defines the sensitivity of the EyeLink II parser for saccade event generation. Normal is intended for cognitive tasks like reading; while High is intended for psychophysical tasks where small saccades must be detected. Keys: X = toggles Saccade Sensitivity Select File Sample Filter for data in the EDF file. Each increase in filter level reduces noise by a factor of 2 to 3. Keys: F2 = toggles File Sample Filter levels

Note: By changing the file sample filter from high to another value this will affect EyeLink Data Viewer and other analysis tool calculations. SR Research Ltd recommends leaving this value set to High.

Select Link/Analog Filter. Each increase in filter level reduces noise by a factor of 2 to 3 but introduces a 1sample delay to the link sample feed. Keys: A= toggles Filter Select Samples to record data samples to the EyeLink II Data File. Select Events to record eye Events to the EyeLink II Data File. Keys: F = toggles File Data Contents

Save the eye position in direct to the EyeLink II

Data File. Keys: 3 = Raw Eye Position Record eye-rotation angle to the EyeLink II Data File. Keys: 4 = HREF Position

Record gaze position data in the EyeLink II Data File output. Keys: G = Gaze Position Record all button presses to the EyeLink II Data File. Keys: B = Button Flags Record external device data into the EyeLink II Data File. Keys: I = Input Port Data Select to view previous screen. Keys: ESC= Previous Screen Select to view camera setup screen. Keys: ENTER = Camera Setup Press Help (F1) to access the online help page for Set Option. All available key shortcuts are also listed on the Help screen. Keys: F1 = open Help screen Press “Revert to Last” to restore the EyeLink II settings to the values loaded the last time the tracker was started. Press “Load Defaults” to load the EyeLink II settings specified in the defaults.ini file. Keys: L= Revert to last configuration from last session. Keys: D= Loads default configuration.

2.3.3.3 Key Shortcuts

Key Function

C Calibration Type P Pacing Delay (For auto-sequence) R Randomize calibration order 1 Repeat first point of calibration M Mouse simulation of eye S Pupil size type E Eye event data (to saccade detector) X Saccade detector sensitivity F2 File sample data filter level F3 Link/Analog data filter level F File data contents selection 3 Raw eye position in samples 4 HREF eye position in samples G Gaze position and resolution in samples B Button flags in samples I Input Port data in samples A Analog output data selection ENTER Camera Setup screen ESC Return to previous screen F1 HELP screen L Revert to configuration from last session. This is still saved even

when the PC is turned off.

D Load default configuration (Default.ini)

2.3.4 Calibration Screen

Status Panel

Sequence Options

Calibration sequence point

Camera view with threshold status

Figure 2-5: EyeLink II Calibration Screen

2.3.4.1 Purpose

Calibration is used to collect fixations on target points, in order to map raw eye data to either gaze position or HREF data. Targets are presented for the participant to fixate on the Display PC while feedback graphics are presented to the experimenter on this display. The calibration is automatically checked when finished, and diagnostics given.

Calibration should be performed after camera setup and before Validation.

The two camera images, along with threshold values, are at the bottom left of the screen. The eyes to be calibrated as well as the calibration type (as defined in the Set Options screen or via the EyeLink API) are indicated beside the camera images at the bottom of the screen. The calibration status and current calibration point being presented are indicated on the bottom right of the screen.

To perform a calibration, have the participant look at the first fixation point and press the “Accept Fixation” button, or the ENTER or Spacebar key, to start the validation. If auto trigger is not enabled, repeat this action after each target fixation.

2.3.4.2 Main Functions

Press to go to the camera setup screen. Keys: ENTER = Camera Setup Press to see the help menu which contains a description of the role of this screen and the keys for functions. Keys: F1 = Help screen Terminate Calibration sequence. Keys: ESC = Abort

Press to have a automated calibration sequence. Sequence pacing selected in the setup options menu. Keys: A = Auto Trigger Press to accept calibration fixation. Only works after calibration dot sequence has finished. Keys: ENTER = Accept Fixation

2.3.4.3 Key Shortcuts

Key Function

F1 Help screen ESC Camera setup A Auto calibration set to the pacing selected in Set Options

menu. (Auto trigger ON). EyeLink accepts current fixation

if it is stable. During Calibration ENTER Begins calibration sequence or accepts calibration value

given. ESC Terminates calibration sequence.

M Manual calibration (Auto trigger turned off.) A Auto calibration set to the pacing selected in Set Options

menu. (Auto trigger ON). EyeLink accepts current fixation

if it is stable. After Calibration F1 Help screen ENTER Accept calibration values V Validate calibration values ESC Discard calibration values

2.3.5 Validation Screen

Status Panel

Sequence Options

Validation sequence point

RichEditWindow

Figure 2-6: EyeLinkII Validation Screen

Camera view with threshold status

2.3.5.1 Purpose

The Validate screen displays target positions to the participant and measures the difference between the computed fixation position and the fixation position for the target obtained during calibration. This error reflects the gaze accuracy of the calibration. In addition, the average offset is used to perform an immediate drift correction. The functionality available in the Validate screen is very similar to that of the Calibrate screen.

Validation should only be performed after Calibration.

To perform a validation, have the subject look at the first fixation point and press the “Accept Fixation” button, or the ENTER or Spacebar key, to start the validation. If auto trigger is not enabled, repeat this action after each target fixation.

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EyeLink II User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual