Welcome Guest, you are in: Login

ScrewTurn Wiki



Search the wiki


EyeLink Tracker Element

Modified on 2016/05/17 17:53 by Maria Categorized as Elements, Eye Trackers
Element Icon EyeLink Tracker Element
Category: Eye Trackers AddIn: EyeLink eye-tracking
Creator: OkazoLab Team Scope: Entire experiment (global)
Owns Snippets: no Usage: Runtime Screen,Snippets

Actions aligned with epochs of the parent event

After OnsetThe element starts analyzing the selected signal
Control Loop stepLatest signal samples is analyzed within the selected analysis window and the signal plot gets updated.
Before OffsetThe element stops analyzing the selected signal


Generic Properties

NameDescriptionAttributesValue TypeProxy Changed Actions
EyeLink settings
Remote IP AddressThe network address of a EyeLink computer in IP format: xxx.xxx.xxx.xxxString
Gaze ModeIndicates what eye is used for tracking within EventIDE via the Radar properties.stTrackedTarget
Blinks via Pupil SizeIf true, the detection of blinks based on the zero pupil size is used. Boolean
Min Pupil SizeThreshold for pupil size. If measured value is smaller that given value a blink is detected instead of a change in the eye position.Single
Smoothing RatioDefines a ratio for the fast FIR smoothing filter, which is applied to the gaze tracking within EventIDE. The filter convolves every new tracking position with the previous ones. The property value defines a tap weight for the previous data, such that the convolution looks like: X=(Xn*(1-Ratio)+Xn-1*Ratio)/2. The value has to be positive and less than 1 (0 means no filtering).Double
Tracker Samples
Current SamplesReturns an array of Array the raw tracker samples taken in the last iteration of the control loop.Sample
Newest SampleReturns the newest raw tracker sample taken in the last iteration of the control loop.Sample
EDF Logging
EDF log Folder String
Is EDF LoggingTurn on/off logging with EDF file on the EyeLink host computer. Boolean
Include EventsTurn on/off EyeLink events logging in EDF file. Boolean
Send MessageRuntime command that sends a custom EDF message (if the EDF Logging is enabled) to an EDF file String

+=== Properties inherited from clTrackerElement ===
NameDescriptionConstraintsTypeUpon Runtime Change
GLM Calibration
Run GLM CalibrationRuns the GLM calibration procedure, which calculates two pairs of linear coefficients for mapping of the tracker input into the screen coordinates. The calculated coefficients are automatically applied at runtime. Boolean
Gain XDefines the gain coefficient for the X axis in the GLM calibration model: X='GainX'*x+OffsetX Double
Gain YDefines the gain coefficient for the Y axis in the GLM calibration model: Y=GainY*y+OffsetY Double
Offset XDefines the offset coefficient for the X axis in the GLM calibration model: X=GainX*x+OffsetX Double
Offset YDefines the offset coefficient for the Y axis in the GLM calibration model: Y=GainY*y+OffsetY Double
Drift Correction
Recalibrate NowRuntime command that helps to correct drifts in tracking data.Correction is done by recalibration of the latest tracker position into a custom screen point defined by the 'Recalibration Point' property.nAs result, the offsets of the GLM calibration get adjusted (but not gains) to compensate a drift in further data. Boolean
Recalibration PointDefines the screen point to which the tracker position will be recalibrated on calling 'Recalibrate Now' action. The default auto value always denotes the screen center. clPoint
Log FolderOpens the dialog for selecting a local folder that will hold all tracking logs String
Open Log DesignerOpens a designer window where the log format can be defined. Boolean
Is LoggingDefines whether logging is turn on/off. The value can be changed at any moment at runtime allowing selective logging during the relevant periods only. Boolean
User FieldDefines the custom user data that is added to every line in the log file. The property can be used for recording varying status information (e.g. trial number) together with the tracker data. The string value may contains multiple fields separated by delimiter. StringOnce a string value is assigned, it is added to every new upcoming line in the log until a new assignment is made.

+=== Properties inherited from clElement === Inherited properties of clElement
NameDescriptionConstraintsValue TypeUpon Change
Is EnabledIf set to false the element is completely omitted when the experiment is run.Boolean
TitleTitle of the element.String

EyeLink Tracker element provides support for all models of EyeLink eye-trackers.


Short description


Snapshot 1

Snapshot 1

Snapshot 2

Snapshot 2

Practical Use

Technique 1

  1. Step 1
  2. Step 2

Technique 2

  1. Step 1
  2. Step 2

 // Check the trial outcome. Result and RT just other user variables
// insert code snippet here..


  • Insert Notes here..
  • Insert Notes here..
  Name Size
- EyeLinkElement.png 32.12 KB

ScrewTurn Wiki version Some of the icons created by FamFamFam.