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Storing upright turns: how visual and vestibular cues interact during the encoding and recalling process.

Vidal M, Bülthoff HH - Exp Brain Res (2009)

Bottom Line: First, we found that in none of the conditions did the reproduced motion dynamics follow that of the presentation phase (Gaussian angular velocity profiles).Third, when the intersensory gain was preserved, the bimodal reproduction was more precise (reduced variance) and lay between the two unimodal reproductions.Fourth, when the intersensory gain was modified, the bimodal reproduction resulted in a substantially larger change for the body than for the visual scene rotations, which indicates that vision prevails for this rotation displacement task when a matching problem is introduced.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Biological Cybernetics, Tübingen, Germany. manuel.vidal@college-de-france.fr

ABSTRACT
Many previous studies have focused on how humans combine inputs provided by different modalities for the same physical property. However, it is not yet very clear how different senses providing information about our own movements combine in order to provide a motion percept. We designed an experiment to investigate how upright turns are stored, and particularly how vestibular and visual cues interact at the different stages of the memorization process (encoding/recalling). Subjects experienced passive yaw turns stimulated in the vestibular modality (whole-body rotations) and/or in the visual modality (limited lifetime star-field rotations), with the visual scene turning 1.5 times faster when combined (unnoticed conflict). Then they were asked to actively reproduce the rotation displacement in the opposite direction, with body cues only, visual cues only, or both cues with either the same or a different gain factor. First, we found that in none of the conditions did the reproduced motion dynamics follow that of the presentation phase (Gaussian angular velocity profiles). Second, the unimodal recalling of turns was largely uninfluenced by the other sensory cue that it could be combined with during the encoding. Therefore, turns in each modality, visual, and vestibular are stored independently. Third, when the intersensory gain was preserved, the bimodal reproduction was more precise (reduced variance) and lay between the two unimodal reproductions. This suggests that with both visual and vestibular cues available, these combine in order to improve the reproduction. Fourth, when the intersensory gain was modified, the bimodal reproduction resulted in a substantially larger change for the body than for the visual scene rotations, which indicates that vision prevails for this rotation displacement task when a matching problem is introduced.

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Plots of all the reproduced velocity profiles of a standard subject according to each of the six studied conditions. The Gaussian velocity profile of the presentation phase is plotted in black thick line. Both the velocity and the time were normalized in order to focus on the profile shape only and to be able to compare them across conditions (see the text for more details about these normalizations)
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Fig3: Plots of all the reproduced velocity profiles of a standard subject according to each of the six studied conditions. The Gaussian velocity profile of the presentation phase is plotted in black thick line. Both the velocity and the time were normalized in order to focus on the profile shape only and to be able to compare them across conditions (see the text for more details about these normalizations)

Mentions: Figure 3 shows all the reproduction velocity profiles of a standard subject (gray lines) together with the Gaussian velocity profile of the presentation phase (black thick line) for each of the six conditions studied. The subject was selected as the closest to median values of the RMSE (described above) obtained for each condition. The time axis was normalized with the motion duration of each reproduction plotted, cutting the start and end tails where subjects did not move with the joystick. The velocity axis was normalized with the peak velocity of each reproduction. Applying the same normalizations to the presented velocity profile leads to a unique Gaussian curve shown in black in each condition plot. A quick qualitative comparison when reading these plots allows stating that the overall shape of the reproduced profiles does not match the Gaussian presented profiles. Rather, the strategy adopted by subjects seems to rely on the use of well-controlled trapezoidal rotational velocity profile, showing an initial linear speed increase in order to reach the speed of the plateau that is then held constant for most of the reproduction duration before decreasing to stop the motion. The decreasing period being subjected to some corrections, it results in the larger spread observed in the plots as compared to the increasing period.Fig. 3


Storing upright turns: how visual and vestibular cues interact during the encoding and recalling process.

Vidal M, Bülthoff HH - Exp Brain Res (2009)

Plots of all the reproduced velocity profiles of a standard subject according to each of the six studied conditions. The Gaussian velocity profile of the presentation phase is plotted in black thick line. Both the velocity and the time were normalized in order to focus on the profile shape only and to be able to compare them across conditions (see the text for more details about these normalizations)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2800859&req=5

Fig3: Plots of all the reproduced velocity profiles of a standard subject according to each of the six studied conditions. The Gaussian velocity profile of the presentation phase is plotted in black thick line. Both the velocity and the time were normalized in order to focus on the profile shape only and to be able to compare them across conditions (see the text for more details about these normalizations)
Mentions: Figure 3 shows all the reproduction velocity profiles of a standard subject (gray lines) together with the Gaussian velocity profile of the presentation phase (black thick line) for each of the six conditions studied. The subject was selected as the closest to median values of the RMSE (described above) obtained for each condition. The time axis was normalized with the motion duration of each reproduction plotted, cutting the start and end tails where subjects did not move with the joystick. The velocity axis was normalized with the peak velocity of each reproduction. Applying the same normalizations to the presented velocity profile leads to a unique Gaussian curve shown in black in each condition plot. A quick qualitative comparison when reading these plots allows stating that the overall shape of the reproduced profiles does not match the Gaussian presented profiles. Rather, the strategy adopted by subjects seems to rely on the use of well-controlled trapezoidal rotational velocity profile, showing an initial linear speed increase in order to reach the speed of the plateau that is then held constant for most of the reproduction duration before decreasing to stop the motion. The decreasing period being subjected to some corrections, it results in the larger spread observed in the plots as compared to the increasing period.Fig. 3

Bottom Line: First, we found that in none of the conditions did the reproduced motion dynamics follow that of the presentation phase (Gaussian angular velocity profiles).Third, when the intersensory gain was preserved, the bimodal reproduction was more precise (reduced variance) and lay between the two unimodal reproductions.Fourth, when the intersensory gain was modified, the bimodal reproduction resulted in a substantially larger change for the body than for the visual scene rotations, which indicates that vision prevails for this rotation displacement task when a matching problem is introduced.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Biological Cybernetics, Tübingen, Germany. manuel.vidal@college-de-france.fr

ABSTRACT
Many previous studies have focused on how humans combine inputs provided by different modalities for the same physical property. However, it is not yet very clear how different senses providing information about our own movements combine in order to provide a motion percept. We designed an experiment to investigate how upright turns are stored, and particularly how vestibular and visual cues interact at the different stages of the memorization process (encoding/recalling). Subjects experienced passive yaw turns stimulated in the vestibular modality (whole-body rotations) and/or in the visual modality (limited lifetime star-field rotations), with the visual scene turning 1.5 times faster when combined (unnoticed conflict). Then they were asked to actively reproduce the rotation displacement in the opposite direction, with body cues only, visual cues only, or both cues with either the same or a different gain factor. First, we found that in none of the conditions did the reproduced motion dynamics follow that of the presentation phase (Gaussian angular velocity profiles). Second, the unimodal recalling of turns was largely uninfluenced by the other sensory cue that it could be combined with during the encoding. Therefore, turns in each modality, visual, and vestibular are stored independently. Third, when the intersensory gain was preserved, the bimodal reproduction was more precise (reduced variance) and lay between the two unimodal reproductions. This suggests that with both visual and vestibular cues available, these combine in order to improve the reproduction. Fourth, when the intersensory gain was modified, the bimodal reproduction resulted in a substantially larger change for the body than for the visual scene rotations, which indicates that vision prevails for this rotation displacement task when a matching problem is introduced.

Show MeSH