Mechanisms of active vison in barn owls: Stable perception through atomic head movements

• Applicant: Professor Dr. Hermann Wagner
• Subject Area: Sensory and Behavioural Biology
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 233611230

In order to survive most animals have to acquire and scale sensory information in reference to the physical world to guide behavior. Information may be either collected passively, analyzing incoming sensory information, or actively, by the actions of the animals. This proposal investigates visual size discrimination in the barn owl as a special case. The project is divided into three work packages. The goal in the first work package is to describe and determine how well the barn owl is capable to discriminate objects of different sizes. The second work package introduces different distances as a case of generalization and investigates the phenomenon of size constancy in barn owls. The third work package will tackle the question how the barn owl uses motion parallax in an active fashion, not only to infer distance, but also the size of an object. The latter approach is also designed to improve our functional understanding of the conspicuous side-to-side head movements observed in barn owls. Experiments with human subjects will be carried out in parallel. They will yield interesting independent data characterizing aspects of the human visual system. From this studies a visual scaling factor should result that might be compared between species to advance our understanding of visual behaviors from an evolutionary perspective. We think that this research may eventually lead to a better understanding of visual orientation and may be valuable for application purposes.

• DFG Programme: Research Grants