Illusory directional hearing in humans.

Trains of 8 binaural clicks, 4 left-ear-leading followed by 4 right-ear-leading, were presented to 14 healthy adults. At interstimulus intervals of less than 120 ms, the subjects mislocalized the sounds, perceiving illusorily that the clicks jumped in equidistant steps from left to right. However, monaural clicks, left-sided followed by right-sided, did not produce a similar effect. The illusion thus has strict neuronal constraints: activation of overlapping neuronal populations in rapid succession. In such conditions the brain integrates sound locations for 100-150 ms and the conscious perception may be delayed by about 500 ms.