User manual

80 An EyeLink 1000 Tutorial: Running an Experiment

ii. Create a full-screen window, and send a series of commands to the

tracker to configure its display resolution, eye movement parsing

thresholds, and data types.

iii. Using a dialog box built into the EyeLink programming library, ask for a

file name for an EDF data file, which it commands the EyeLink tracker to

open on the Host PC hard disk.

iv. Run a block of trials. Each block begins by calling up the tracker’s Setup

menu screen, from which the experimenter can perform camera setup,

calibration, and validation. Four trials are run, each of which displays a

single word.

v. After all blocks of trials are completed, the EDF file is closed and

transferred via the link from the EyeLink hard disk to the Display PC.

vi. At the end of the experiment, the window is closed and the EyeLink

library is closed.

Each trial begins by performing an optional drift correction, where the subject

fixates a target to allow the eye tracker to correct for any drift errors. Press the

space bar to perform the drift correction. Recording is then started. Recording

can be stopped by pressing the ‘Esc’ key on the Display PC keyboard, the

EyeLink Abort menu (‘Ctrl’ ‘Alt’ ‘A’ on the Host keyboard) or by pressing

any button on the EyeLink button box.

B. Text

This experiment is an extension of the Simple experiment and uses a slightly

more complex process for drawing to the Display PC monitor. For more complex

display such as screens of text or pictures, drawing takes too long to complete

in one or two display refreshes. This makes the drawing process visible, and

there is no clear stimulus onset for reaction time measurement. The code in the

“text” template draws to a bitmap (an image in computer memory, not to the

display), then copies it to the Display PC monitor, reducing the time to make

the display visible. This also has the advantage of making the trial code more

general: almost any stimulus can be displayed given its bitmap.

C. Picture

The template “Picture” is almost identical to “Text”, except that images are

loaded from BMP or JPEG files and displayed instead of text.

D. EyeData

This template introduces the use of the link in transferring gaze-position data.

This data can be used for gaze contingent or gaze control type paradigms. Gaze

position data can be transferred in real time, or played back after recording has

ended, which helps to separate recording from analysis.