The Role of Eye Gaze in Subjective Decision Making
Shimojo, Simion, Shimojo and Scheier (2003) provided preliminary evidence that eye movements have an active role in preference formation. In their study, subjects were presented with two faces and chose which was more attractive. By manipulating how long subjects were able to look at each face after an eye movement, Shimojo et al. (2003) showed that faces presented for a longer duration were more likely to be chosen as more attractive. However, a recent study from Nittono and Wada (2009) showed that an eye movement may not be necessary for this effect, as novel graphic patterns presented in the centre of the screen (thus requiring no eye movements) for longer durations were also more likely to be preferred. The purpose of the current study was to further investigate whether eye movements do have an active role in preference formation. The present study used the same paradigm as Shimojo et al.’s (2003) study. Subjects in Experiment 1 were presented with images of two real faces, alternatively (one for 900ms, one for 300ms) for six repetitions. There were 3 independent experimental conditions. One group were required to make eye movements to laterally presented faces and judge attractiveness (lateral attractiveness condition), a second were not required to make eye movements to centrally presented faces and judge attractiveness (central attractiveness condition). The third were required to make eye movements to laterally presented faces and judge roundness (lateral roundness condition). The findings indicated that subjects were more likely to choose the longer presented faces in the lateral attractiveness and central attractiveness conditions, but not the lateral roundness conditions. Experiment 2 was similar to Experiment 1 with the exception of the type of stimuli, which consisted of computer generated faces (CGFs). Subjects were more likely to choose the longer presented CGF in the lateral attractiveness, central attractiveness and lateral roundness conditions. The findings of the present study were not in line with Shimojo et al.’s (2003) previous findings, who found that faces presented for a longer duration were only preferred in the lateral attractiveness condition of their study. It is possible that the faces that are presented for the longer duration in the current paradigm are preferred due to the increase in exposure duration irrespective of an eye movement (as per the findings from Nittono and Wada, 2009). As it is unclear as to whether eye movements play an active role in preference formation, the findings of the present study have not been able to contribute to computational models of decision making.