Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences


Decision-Making, Eye-movements, Gaze Bias, Preference


Lori Buchanan




Visual decision-making is a common action that recruits a complex set of cognitive processes. When first presented with an option set from which to choose, participants can rely on one of two distinct decision strategies, preferential and empirical. In a preferential choice, participants choose their most preferred option; there is frequently a so-called gaze bias effect in such choices, where the gaze directed at the chosen option is longer than the gaze at unchosen options. In empirical choices, participants select an objectively correct choice from a set of distractors; these decisions have been shown to produce similar or weaker effects of the gaze bias. Although both forms of decision-making are the subject of scientific investigation, there are no studies that directly compare and contrast the two types. My project is the first to investigate the two decision types using a within-participants experimental design. Participants chose between option pairs in a 2-alternate-forced-choice task with trials grouped into 2 blocks: empirical and preferential. In the empirical block, option pairs contained one correct and one incorrect choice whereas in the preferential condition, option pairs were equal in value (i.e., no correct or incorrect choice). Reaction times for each choice, the number of looks, and duration of gaze for each option were recorded using a computer and eye tracker. To test whether the gaze bias effect occurs equally across these two decision types, different decision stimuli (features, math expressions, and words related to social biases) were used. These experiments thus help to differentiate between preferential and empirical decision using a novel method. Further, by introducing social influences in the manipulations, this research also extends our understanding of social influences on decision-making.