Figure 2.

Group means of the dominance fractions. The average fraction of simultaneous dominance across observers for all possible grouped percepts. Error bars represent SEM. Fractions are plotted for each condition. Each bar represents the fraction of dominance for two targets. The dotted line represents unbiased dominance. The results show that when identical rival targets are presented to the same eye, there is a bias toward orientation-based grouping. This is not the case when identical targets are split between the eyes. The bias toward grouping is further increased when identical targets are presented within the same hemifield as well as to the same eye. However, when identical targets are presented to different eyes, the bias is decreased (a bias away from grouping) for presentation in the same compared to different hemifields. These results suggest a strong preference for visual information presented to one eye to be simultaneously dominant.