Preference formation, which is fundamental to personality and daily behavior, is affected by eye movements (i.e. attention). In the last two decades, much research has examined the relationship between decision-making, such as preference formation, and attention (e.g. Smith & Krajbich, 2018). For example, Krajbich and his colleagues showed that gaze toward an option can be considered to be a facilitator of the option's value and that the value of the option can be modeled computationally by using a measure of gazing time toward the option (Krajbich, Armel, & Rangel, 2010; Krajbich & Rangel, 2011). Moreover, manipulating gazing patterns toward each option unconsciously affects a choice (Pärnamets et al., 2015; Shimojo, Simion, Shimojo, & Scheier, 2003). Thus, it is apparent that attention has a crucial role in decision-making. The gaze bias effect is one of the well-known phenomena demonstrating the role of attention on decision-making. When people are faced with a decision, their gaze tends to be biased toward the option they finally choose. This phenomenon is known as the gaze bias effect and has received attention from many scholars