FOOD STIMULI AND GENDER

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3.5.2 Coding Procedure and Validation
The eye-tracking video-based recordings must be encoded or mapped into snapshots
to obtain the coordinates of the eye movements necessary for data analysis.
Snapshots
Snapshots were taken of each slide of each randomized presentation using a Canon
PowerShot G9 X camera. A total of 2,263 snapshots were taken, all with the same manual
settings: ISO-160, exposure 1/60, focal distance 10 mm, and no flash.
Encoding
The encoding procedure was performed using the Tobii Pro Glasses Analyzer
Version1.36.1430 (x64) Software. The auto-mapping tool of the Tobii Pro Glasses Analyzer
Software was used when possible; when this function did not work, the points were encoded
manually.
Four people were assigned to this task. To ensure a high reliability between all
coders, three training sessions were conducted, and an encoding protocol was implemented
(see Appendix F). The four people performed a total of three reliability tests of the ET
recording until a match of greater than 90 % was achieved with deviations of less than 1%
(see Appendix G).
3.5.3 Data Preparation and Data Analysis
Once the coding of the raw eye-tracking data was accomplished, a velocity-threshold
identification (IV-T) filter was applied to all projects before the data was exported. A filter
is important in order to classify the fixations, “If the velocity of the eye movement is below
a certain threshold, the samples are classified as part of a fixation, and if the velocity is above
the threshold is classified as a saccade” (Tobii AB Technology, 2015). The I-VT filter