Abstract

Flying bees make extensive use of optic flow: the apparent motion in the visual scene
generated by their own movement. Much of what is known about bees’ visually-guided
flight comes from experiments employing real physical objects, which constrains the
types of cues that can be presented. Here we implement a virtual reality system allowing
us to create the visual illusion of objects in 3D space. We trained bumblebees, Bombus
ignitus, to feed from a static target displayed on the floor of a flight arena, and then
observed their responses to various interposing virtual objects. When a virtual floor was
presented above the physical floor, bees were reluctant to descend through it, indicating
that they perceived the virtual floor as a real surface. To reach a target at ground level,
they flew through a hole in a virtual surface above the ground, and around an elevated
virtual platform, despite receiving no reward for avoiding the virtual obstacles. These
behaviors persisted even when the target was made (unrealistically) visible through the
obstructing object. Finally, we challenged the bees with physically impossible ambiguous
stimuli, which give conflicting motion and occlusion cues. In such cases, they behaved
in accordance with the motion information, seemingly ignoring occlusion.