Figure 4.

Arena boundary and not vertical surfaces are preferred. (A). An arena was constructed with internal concentric walls. For analysis, the arena was subdivided into four zones. (B). The behavior of flies was examined in the concentric circle arena having either transparent or opaque walls. When the walls were clear, wild-type Canton-S spent 92.7% of the time in the outermost zone. This is significantly more time than when the walls were opaque (65.2%, P <0.0001). The neutral expectation is derived from the percent area of each zone. n = 32 for each experiment.