# Effect of Scents on Gazing Behavior and Choice
### Gazzing Behavior  
Eye tracking has long been a widely applied technique to study visual attention in individuals, with the most common method being pupil-centered corneal reflectance (PCCR). Eye-trackers track all of the eye movements of a participant, i.e., where the person looks and for how long, where they looked first and how much time they spend looking at that particular product. There have been many studies on the \"_lose at first sight_\" choice. Some have argued that choice can be predicted by which product the subject fixated on first, but [PERSON] and colleagues have refuted this claim [24]. With an eye-tracker, we can measure the followings: gaze direction and gaze point, detection of eye presence, eye position, eye identification, eyelid closure and pupil dilation and size [25]. In their 2013 paper, [PERSON] and [PERSON] [26] reviewed studies on eye movements in decision making and compare their observations with theoretical predictions about the role of attention in decision making. An important conclusion of this review is that attention plays an active role in decision making. In contrast to the assumption of passive information acquisition, attention has been shown to be driven not only by information demands, but also by bottom-up processes and interactions with working memory. The final decision is shaped by complex interactions between stimuli, attentional processes, working memory and preferences, and it is, therefore, reasonable to conclude that attention plays a constructive role in decision-making. It can also be inferred that the cognitive processes that drive eye movements during decision making are not consistently different from those in similar tasks. Attentional processes, such as top-down or bottom-up attention capture or learning effects on fixations, play similarly important roles in decision making, problem solving, visual search and scene viewing. [PERSON] and colleagues focused their research on using eye-tracking as a method to understand children's consumer preferences. The results support the use of visual attention measures as an implicit tool to analyze children's decision making and preferences. Additionally, their results also revealed that stimuli determine the largest amount of fixations and that viewing times are different across genders [27]. When working with advertisements, it has been shown that \"_sniffing a scent while viewing a print at diverts visual attention_ (total gaze duration) _to a visual object in the ad when the object is semantically congruent with the scent, controlling for total time spent looking at the ad\"_[20]. This effect was more pronounced in direct scenarios (e.g., lemon scent and lemon picture) compared to indirect ones (citrus scent and cleanser). Several studies have demonstrated that visual cues affect olfactory performance [28; 29; 30]. For example, when an odor is correctly paired with a color, participants perceive it as more pleasant than when they are incorrectly paired [31]. It was also shown that looking at congruent pictures increased the intensity of odors and made them more pleasant than incongruent pairing [32]. In addition, several studies have investigated the ability of odors to modulate the behavior of participants in response to visual stimuli [33; 34; 35; 36]. [PERSON] and colleagues [37] investigated how subliminal exposure to odors influences the choice of snacks with similar taste characteristics and whether this is modulated by visual attention. The test used odors that were associated with salty/savory or sweet food. Their results showed that the participants fixated first on the product that could be paired with the particular odor: if they smelled salty/savory, most people fixated on salty/savory snacks first, and vice versa for sweet snacks. However, they fixated on sweet snacks more often and for longer periods of time, and chose them more often, regardless of which odorant was released. Participants spent more time looking at incongruent snack products during the first fixation.