Summary: Kelley & Endler (2012)

Visual illusions are created when object or scene geometry is changed to trick the perception of the viewer when observing that scene/object from a specific direction. While many studies on sexual selection aim to compare signal strength, the components of the signal, and the processing of the information by the receiver's senses may interact to form visual illusions that are misleading (or are designed to capture attention). Kelley & Endler (2012) found that male great bowerbirds Ptilonorhynchus nuchalis create forced-perspective illlusions to female perceiver's in the bower avenue by actively maintaining size-distance gradients of the objects they use to create the bower court. They found that mating success and the female's perception of the gradient are significantly related and suggest that the use of illusions in mating and courtship might be more widespread than originally thought, based on orientation and distance characteristics used by males of multiple species.