Fig. 1. Bimodal and unimodal learning of shape using echolocation and vision.

Learning curves of bats trained to discriminate between a prism and a cylinder under different sensory conditions. Inset shows front-bottom view of the two targets (the direction from which the bats approached) and top view of the experimental setup. For a more detailed setup, see Fig. 2B (the experiment had identical setup with different targets). The different colors depict different individuals. The red horizontal dashed line indicates chance level, while the gray dashed line indicates 75% success. (A) Training under conditions that allowed usage of both vision and echolocation. (B) Training using echolocation only. (C) Training using vision only. (D) Training with both vision and echolocation abolished. When using vision only (C), the bats immediately solved the discrimination task within one session. If there were other cues available, then the bats should have immediately solved the task in the other cues condition (D) as well. Therefore, we only trained the bats for several sessions under this condition. In all experimental conditions, bats performed one training session (with 24 trials on average) per day.