Independence of Echo-Threshold and Echo-Delay in the Barn Owl
(A) Placement of 10 loudspeakers and a central fixation LED, in polar coordinates. In trials with a lead/lag pair, one of the pair of speakers was assigned a radius of 10°, 15°, 20°, 25°, or 30° and a random polar angle. The second member of the pair had an identical radius, but was 180° opposite the first speaker. Corresponding Cartesian coordinates (azimuth and elevation) are also shown. The stimulus paradigms used in the behavioral trials were identical to those shown in Fig. 1 for physiology. (B) Example of a head saccade. The saccade shown here was made with an unusually large error (30°) relative to that of the closest source, in this case, the lagging source. Despite this error, the angle of the saccade was far greater when compared with that of the leading source (150°), thereby allowing us to determine whether the saccade was lead- or lag-directed. The color scale indicates saccade velocity.