The memory template in Drosophila pattern vision at the flight simulator.

Pattern recognition is studied in flight orientation of fixed flying Drosophila melanogaster controlling the horizontal rotations of an arena. Earlier experiments had suggested a simple mechanism of pattern recognition in which a memory template and the actual image are retinotopically matched. In contrast, we now show that Drosophila extracts at least two and probably four pattern parameters: size, vertical position of the center of gravity and, presumably horizontal/vertical extent as well as vertical separatedness of pattern elements. Moreover, the fly treats isolated pattern elements as a compound figure. Retinal transfer is possible between training and test if the centers of gravity of the compound figures are retained.