Data Files
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2016-2017 SR Research Ltd.
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saccade_velocity_threshold = 30
saccade_acceleration_threshold = 8000
saccade_motion_threshold = 0.1
saccade_pursuit_fixup = 60
fixation_update_interval = 50
Psychophysical configuration:
recording_parse_type = GAZE
saccade_velocity_threshold = 22
saccade_acceleration_threshold = 3800
saccade_motion_threshold = 0.0
saccade_pursuit_fixup = 60
fixation_update_interval = 50
4.4 File Data Types
The data contents of an EDF file are organized in two streams: samples and
events. Samples are used to record instantaneous eye position data, while
events are used to record important occurrences, either from the experimental
application or from changes in the eye data.
Both samples and events can report eye data in several forms. These are
discussed in the description of sample data. Eye movement data is parsed by
the EyeLink tracker on-line and used to generate eye-movement events, which
are discussed with application messages and button events.
4.4.1 Samples
Samples are records of eye-position, pupil size, and button or input states.
Some versions of EyeLink trackers can record up to 2000 samples per second in
a monocular tracking mode or up to 1000 samples per second in a binocular
tracking mode (actual sampling rate depends on your system model,
configuration and licensing). Each sample is stored as a binary record in the
EDF file, with simple compression used to minimize disk space. Even with
compression, recording 1000 samples per second will create very large EDF
files: about 15K of data per second.
Each sample may contain several data fields, including:
•
Time of the sample (timestamp) in milliseconds
•
Eye position data in gaze, HREF, or RAW data, monocular or binocular
•
Pupil size, monocular or binocular
•
Button or input port state bits
