Upper nasal hemifield location and nonspatial auditory tones accelerate visual detection during dichoptic viewing

Impact of sectorial hemifield occlusions on the motion perception of rotating snake illusion

This study investigates the impact of sectorial hemifield occlusions on the perception of the rotating snake illusion, a well-studied optical phenomenon. The rotating snake illusion induces the perception of movement in a static image and has been linked to cortical activation in areas such as hMT+ and MT. Binasal sectorial hemifield occlusions (BNO), which partially obscure the retina, have been explored in relation to mild traumatic brain injury and associated with increased visual evoked potentials. However, the mechanisms by which these occlusions modulate the perception of this illusion remain unclear. This study compared the effects of BNO and bitemporal occlusion (BTO) on the rotating snake illusion. Neurotypical participants rated the illusion's movement on a scale while being exposed to different occlusions. The results revealed that both BNO and BTO affect the perception of movement in the rotating snake illusion relative to baseline, but there was no evidence for a difference between these effects.

A nasal visual field advantage in interocular competition

When our eyes are confronted with discrepant images (yielding incompatible retinal inputs) interocular competition (IOC) is instigated. During IOC, one image temporarily dominates perception, while the other is suppressed. Many factors affecting IOC have been extensively examined. One factor that received surprisingly little attention, however, is the stimulus’ visual hemifield (VHF) of origin. This is remarkable, as the VHF location of stimuli is known to affect visual performance in various contexts. Prompted by exploratory analyses, we examined five independent datasets of breaking continuous flash suppression experiments, to establish the VHF’s role in IOC. We found that targets presented in nasal VHF locations broke through suppression much faster than targets in temporal VHF locations. Furthermore, we found that the magnitude of this nasal advantage depended on how strongly the targets were suppressed: the nasal advantage was larger for the recessive eye than for the dominant eye, and was larger in observers with a greater dominance imbalance between the eyes. Our findings suggest that the nasal advantage reported here originates in processing stages where IOC is resolved. Finally, we propose that a nasal advantage in IOC serves an adaptive role in human vision, as it can aid perception of partially occluded objects.