FOOD STIMULI AND GENDER

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3.4 Experimental Procedure
A brief description of the experimental procedure is presented to provide readers
with an overview of how the eye-tracking experiment was accomplished. The experiment
consisted of a single session. Preparation for each experimental session included checking
the projector settings and running the stimuli presentation once before the participant
arrived. Participants were asked to abstain from eating for three hours before visiting the
laboratory to avoid a potential effect of satiation and facilitate a better reaction time in a
hungry state (Doolan et al., 2015; Nijs, Muris, Euser, & Franken, 2010).
Only one participant at a time was allowed in the laboratory for the eye-tracking
presentation. After a participant was welcomed, he or she was asked to turn off his or her
mobile device, read the participant information, and read and sign the consent information
(see Appendix C). Subsequently, he or she was asked to fill out Questionnaire I. For a
detailed description of the questionnaires, please refer to the Data Collection section and
Appendix E. The Tobii Pro 2 glasses were adjusted to the participant’s facial features, and
a calibration of the glasses was performed at a distance of 1 m from the screen using the
calibration target card provided by Tobii Technology. The accuracy error admitted by the
calibration was of less than 0.6 grades. The initial calibration was then validated by a threepoint verification admitting less than 1.2 grades of accuracy error.
After successful calibration, participants were shown the randomized food stimulus
picture presentation without any prior instructions to avoid any induced bias in the viewing
behavior. It is important to evade priming that could influence certain unconscious behaviors
(Aarts, Custers, & Marien, 2008).
After the presentation, participants finished the experiment by completing
Questionnaire II. See the description of the questionnaire in the Data Collection section and