User manual

Data Files

be used to record the time of a change in the display, or an experimental

condition.

4.2 Recording EDF Files

EDF files are created by the EyeLink 1000 tracker, recording eye-position data,

events from the on-line parser, and button and input events. These are recorded

only when the tracker is in output (recording) mode. Messages sent from

applications on the Display PC through the Ethernet link may be recorded at

any time. Recording EDF files involves opening a data file, recording data from

one or more sessions in output mode, and closing the file. These operations can

be performed manually using the EyeLink 1000 Host application on the Host

PC, or remotely from the Display PC through the Ethernet.

4.2.1 Recording from the EyeLink 1000 Host PC

In some eye-tracking situations, it is most convenient to initiate the recording of

eye movement data directly. For example, displays may be generated by

manually-operated equipment, or by non-EyeLink applications. Special

provisions must be made for display of the calibration pattern.

By using the EyeLink 1000 tracker’s Output Screen, files may be opened and

closed, and recording sessions may be started and stopped. Refer to Chapter 2

of this manual “EyeLink 1000 Host application Operation” for information.

4.2.2 Recording from the EyeLink API or SR Research Experiment Builder

Most eye-movement research involves running many subjects through a

sequence of experimental trials, with tens or hundreds of recording blocks per

file. This is best done by remote control over the link from an experimental

application. The connection from the Display PC to the EyeLink 1000 tracker is

implemented by an Ethernet link. Refer to the EyeLink Programmer’s Guide or

SR Research Experiment Builder User Manual for details on how to use the

Display PC software to set up and record EDF files.

4.3 The EyeLink On-Line Parser

The EyeLink 1000 system incorporates a unique on-line parsing system which

analyzes eye position data into meaningful events and states (saccades,

fixations, and blinks). For many experiments, such as reading or cognitive

research, only the events need to be stored in the EDF file, reducing its size by

80% to 95%.