The aftereffects of ventriloquism: generalization across sound-frequencies

Exposure to synchronous but spatially discordant auditory and visual inputs produces, beyond immediate cross-modal biases, adaptive recalibrations of the respective localization processes that manifest themselves in aftereffects. Such recalibrations probably play an important role in maintaining the coherence of spatial representations across the various spatial senses. The present study is part of a research program focused on the way recalibrations generalize to stimulus values different from those used for adaptation. Considering the case of sound frequency, we recently found that, in contradiction with an earlier report, auditory aftereffects generalize nearly entirely across two octaves. In this new experiment, participants were adapted to an 18 degrees auditory-visual discordance with either 400 or 6400 Hz tones, and their subsequent sound localization was tested across this whole four-octave frequency range. Substantial aftereffects, decreasing significantly with increasing difference between test and adapter frequency, were obtained at all combinations of adapter and test frequency. Implications of these results concerning the functional site at which visual recalibration of auditory localization might take place are discussed.