The aftereffects of ventriloquism: Generalization across sound-frequencies (original) (raw)
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Seeing and Perceiving, 2012
Exposure to synchronous but spatially discordant auditory and visual inputs produces adaptive recalibration of the respective localization processes, which manifest themselves in measurable aftereffects. Here we report two experiments that examined the time course of visual recalibration of apparent sound location in order to establish the build-up and dissipation of recalibration. In Experiment 1 participants performed a sound localization task before and during exposure to an auditory-visual discrepancy. In Experiment 2, participants performed a sound localization task before and after 60, 180, or 300 exposures to the discrepancy and aftereffects were measured across a series of post-adaptation sound localization trials. The results show that recalibration is very fast. Substantial aftereffects are obtained after only 18-24 exposures and asymptote appears to be reached between 60 and 180 exposures. The rate of adaptation was independent of the size of the discrepancy. The retention of the aftereffect was strong, as we found no dissipation, not even after as few as 60 exposure trials.
Visual recalibration of auditory spatial perception
2005
Generali~ation across soundfreguencies is unajjerted by nse time Chapter 5 Aftereffects generaGze to non-octave intervals Chapter 6 The aftereffects of ventriloyuísm: Patterns of .rputialgeneruliZation fmm loca! reculibration Chapter 7 Evidence for generalization across sound-frequency and spatial generalization without a directed motor response Chapter 8 The àme course of visual recalibration of auditory localization Chapter 9 General discussion Samenvatting (summar}~in Dutch) 109 References 113 Acknowledgments 127 Vita 129 '"`x' denotes that exposure was distributed ocer a number of blocks, with a subset of post tests interspersed. The fust digit indicates the number of such blocks and the second the number of trials per binck. The same goes for Exposure duration except that the second digit stands Eor the number of minutes the block lasted. "' Díean ahereffect as the proportion of the imposed discrepana.
The aftereffects of ventriloquism: Are they sound-frequency specific?
Acta Psychologica, 2003
Exposing different sense modalities (like sight, hearing or touch) to repeated simultaneous but spatially discordant stimulations generally causes recalibration of localization processes in one or both of the involved modalities, which is manifested through aftereffects. These provide opportunities for determining the extent of the changes induced by the exposure. Taking the so-called ventriloquism situation, in which synchronized sounds and light flashes are delivered in different locations, we examine if auditory recalibration produced by exposing tones of one frequency to attraction by discordant light flashes generalizes to different frequencies. Contrary to an earlier report, generalization was obtained across two octaves. This result did not depend on which modality attention was forced on through catch trials during exposure. Implications concerning the functional site of recalibration are briefly discussed.
Rapidly induced auditory plasticity: The ventriloquism aftereffect
Proceedings of the National Academy of Sciences, 1998
Cortical representational plasticity has been well documented after peripheral and central injuries or improvements in perceptual and motor abilities. This has led to inferences that the changes in cortical representations parallel and account for the improvement in performance during the period of skill acquisition. There have also been several examples of rapidly induced changes in cortical neuronal response properties, for example, by intracortical microstimulation or by classical conditioning paradigms. This report describes similar rapidly induced changes in a cortically mediated perception in human subjects, the ventriloquism aftereffect, which presumably ref lects a corresponding change in the cortical representation of acoustic space. The ventriloquism aftereffect describes an enduring shift in the perception of the spatial location of acoustic stimuli after a period of exposure of spatially disparate and simultaneously presented acoustic and visual stimuli. Exposure of a mismatch of 8°for 20-30 min is sufficient to shift the perception of acoustic space by approximately the same amount across subjects and acoustic frequencies. Given that the cerebral cortex is necessary for the perception of acoustic space, it is likely that the ventriloquism aftereffect ref lects a change in the cortical representation of acoustic space. Comparisons between the responses of single cortical neurons in the behaving macaque monkey and the stimulus parameters that give rise to the ventriloquism aftereffect suggest that the changes in the cortical representation of acoustic space may begin as early as the primary auditory cortex.
Tactile recalibration of auditory spatial representations
Experimental Brain Research, 2011
In the well-known spatial ventriloquism effect, auditory stimuli are mislocalized towards the location of synchronous but spatially disparate visual stimuli. Recent studies have demonstrated a similar influence of tactile stimuli on auditory localization, which predominantly operates in an external coordinate system. Here, we investigated whether this audio-tactile ventriloquist illusion leads to comparable aftereffects in the perception of auditory space as have been observed previously for audiovisual stimulation. Participants performed a relative sound localization task in which they had to judge whether a brief sound was perceived at the same or a different location as a preceding tactile stimulus ("Experiment 1") or to the left or right of a preceding visual stimulus ("Experiment 2"). Sound localization ability was measured before and after exposure to synchronous audio-tactile stimuli with a constant spatial disparity. After audio-tactile adaptation, unimodal sound localization was shifted in the direction of the tactile stimuli during the preceding adaptation phase in both tasks. This finding provides evidence for the existence of an audio-tactile ventriloquism aftereffect and suggests that auditory space (rather than specific audio-tactile connections) can be rapidly recalibrated to compensate for audio-tactile spatial disparities.
Experimental brain research, 2016
Visual capture and the ventriloquism aftereffect resolve spatial disparities of incongruent auditory visual (AV) objects by shifting auditory spatial perception to align with vision. Here, we demonstrated the distinct temporal characteristics of visual capture and the ventriloquism aftereffect in response to brief AV disparities. In a set of experiments, subjects localized either the auditory component of AV targets (A within AV) or a second sound presented at varying delays (1-20 s) after AV exposure (A2 after AV). AV targets were trains of brief presentations (1 or 20), covering a ±30° azimuthal range, and with ±8° (R or L) disparity. We found that the magnitude of visual capture generally reached its peak within a single AV pair and did not dissipate with time, while the ventriloquism aftereffect accumulated with repetitions of AV pairs and dissipated with time. Additionally, the magnitude of the auditory shift induced by each phenomenon was uncorrelated across listeners and visu...
Directing spatial attention towards the illusory location of a ventriloquized sound
Acta Psychologica, 2001
In this study, we examined whether ventriloquism can rearrange external space on which spatial re¯exive attention operates. The task was to judge the elevation (up vs down) of auditory targets delivered in the left or the right periphery, taking no account of side of presentation. Targets were preceded by either auditory, visual, or audiovisual cues to that side. Auditory, but not visual cues had an eect on the speed of auditory target discrimination. On the other hand, a ventriloquized cue, consisting of a tone in central location synchronized with a light¯ash in the periphery, facilitated responses to targets appearing on the same side as thē ash. That eect presumably resulted from the attraction of the apparent location of the tone towards the¯ash, a well-known manifestation of ventriloquism. Ventriloquism thus can reorganize space in which re¯exive attention operates. Ó
Computational Characterization of Visually Induced Auditory Spatial Adaptation
Frontiers in Integrative Neuroscience, 2011
Recent research investigating the principles governing human perception has provided increasing evidence for probabilistic inference in human perception. For example, human auditory and visual localization judgments closely resemble that of a Bayesian causal inference observer, where the underlying causal structure of the stimuli are inferred based on both the available sensory evidence and prior knowledge. However, most previous studies have focused on characterization of perceptual inference within a static environment, and therefore, little is known about how this inference process changes when observers are exposed to a new environment. In this study we aimed to computationally characterize the change in auditory spatial perception induced by repeated auditory-visual spatial conflict, known as the ventriloquist aftereffect. In theory, this change could reflect a shift in the auditory sensory representations (i.e., shift in auditory likelihood distribution), a decrease in the precision of the auditory estimates (i.e., increase in spread of likelihood distribution), a shift in the auditory bias (i.e., shift in prior distribution), or an increase/decrease in strength of the auditory bias (i.e., the spread of prior distribution), or a combination of these. By quantitatively estimating the parameters of the perceptual process for each individual observer using a Bayesian causal inference model, we found that the shift in the perceived locations after exposure was associated with a shift in the mean of the auditory likelihood functions in the direction of the experienced visual offset. The results suggest that repeated exposure to a fixed auditory-visual discrepancy is attributed by the nervous system to sensory representation error and as a result, the sensory map of space is recalibrated to correct the error.
A visual influence in the discrimination of auditory location
1998
The compellingness of the interaction between vision and auditory localization (the ventriloquist effect) was investigated using a discrimination task. A tone sequence was presented either from the same location or from two locations that alternated along the horizontal plane. In synchrony with the tones, lights were presented either at the same or at alternating locations. Subjects had to decide whether the tones alternated or not, thereby ignoring the lights. The main result was that presenting non-alternating tones together with alternating lights increased the number of 'alternating'-judgements, even though subjects were told to ignore the lights, and even though they received corrective feed-back after each trial.