Holding constant other scale features, the direction in which a scale is presented has been found to affect the resulting survey answers; respondents are more likely to select a scale point closer to the start of the scale regardless of its direction, producing primacy effects (Yan, 2015). What remains understudied is the mechanism underlying this scale direction effect. Two common response processing models are offered as possible explanations for these effects: satisficing, and anchoring and adjusting. The satisficing model treats the impact of scale direction as a special case of response order effect and argues that satisficers sequentially process the rating scale and select the first option that seems reasonable. The anchoring-and-adjustment heuristic assumes that respondents start with an initial anchor (the beginning of a scale) and make adjustments to the anchor until a plausible point is reached. Since both notions predict a primacy effect, it is hard to know which notion offers a better account for scale direction effect. To learn more about what’s behind scale direction effects, we will collect eye tracking data from respondents’ as they respond to a web survey. As the eye movement data (e.g., fixation counts and fixation duration) show directly the amount of attention paid to question components, we will first characterize how respondents process a rating scale and how the processing differs respondent characteristics. Then we will explore which of the two notions account for the scale direction effect. This paper demonstrates how eye-tracking can be used to address theoretical issues related to respondents’ use of rating scales.