Honeybee navigation: Linear perception of short distances travelled

Recent evidence indicates that honeybees measure distance flown to a food source by integrating, over time, the apparent visual motion of the environment that they experience en route to the goal. Is the bee's perception of distance travelled a linear function of distance, or is it some other function? This question was investigated by training bees to fly into a tunnel and receive a food reward. The walls and floor of the tunnel were lined with a random texture, and the reward was placed at one of two fixed distances, 'near' or 'far', from the tunnel entrance. The feeder containing the reward was placed in a box which could be accessed through one of two openings, one on the left side of the box, and the other on the right. When the box was at the 'near' position, the reward could only be accessed through the left-hand opening; when the box was at the 'far' position, the reward could only be accessed through the right-hand opening. When the trained bees were tested individually in an identical, fresh tunnel with the reward removed from the box, they showed a strong preference for the left-hand opening when tested at the 'near' distance, and for the right-hand opening when tested at the 'far' distance. At intermediate positions, the bees' preference for the two openings varies linearly with distance. These findings suggest that the honeybee's perception of distance travelled is linear, at least over the distances and range of image motions experienced in our experiments. The implications for navigation and for the encoding of distance information in the dance are discussed.