Influence of acoustic context on sound localization: An auditory Roelofs effect

The Roelofs effect is a visual direction illusion: if a large rectangular frame is seen offset from the straight-ahead direction, a small target presented simultaneously is mislocalized in the opposite direction. To investigate whether a similar context illusion might affect auditory localization, we presented a "frame" of 6 speakers driven with a 300-Hz square wave, 30 degrees left or right of center. The "target" was a speaker driven with the same waveform, with the two sources in random phase relationship. The target was mislocalized in a direction opposite the frame, an auditory Roelofs effect. A second experiment, using dissimilar sounds for frame and target, yielded no frame-dependent mislocalizations. The effect appeared both in verbal position estimation, a measure of cognitive localization, and in open-loop pointing, a measure of localization in a sensorimotor system. We conclude that audition possesses only one representation of space, in contrast to the two (cognitive and sensorimotor) of vision, The auditory representation corresponds most closely to vision's cognitive system.