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Tactile feedback improves auditory spatial localization.

Gori M, Vercillo T, Sandini G, Burr D - Front Psychol (2014)

Bottom Line: Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially congruent.Our results suggest that the tactile system can be used to recalibrate the auditory sense of space.These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality.

View Article: PubMed Central - PubMed

Affiliation: Robotics Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy.

ABSTRACT
Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014). To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds before and after training, either with tactile feedback, verbal feedback, or no feedback. Audio thresholds were first measured with a spatial bisection task: subjects judged whether the second sound of a three sound sequence was spatially closer to the first or the third sound. The tactile feedback group underwent two audio-tactile feedback sessions of 100 trials, where each auditory trial was followed by the same spatial sequence played on the subject's forearm; auditory spatial bisection thresholds were evaluated after each session. In the verbal feedback condition, the positions of the sounds were verbally reported to the subject after each feedback trial. The no feedback group did the same sequence of trials, with no feedback. Performance improved significantly only after audio-tactile feedback. The results suggest that direct tactile feedback interacts with the auditory spatial localization system, possibly by a process of cross-sensory recalibration. Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially congruent. Our results suggest that the tactile system can be used to recalibrate the auditory sense of space. These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality.

No MeSH data available.


(A) Results for the rotated feedback condition. The three data points in the left-hand graph represent the average results for the three bisection thresholds measured: the first one before any feedback (PRE), the second after the first feedback (POST1) and the third after the second feedback (POST2). The plot at right shows the thresholds for all subjects, plotting the thresholds after the second feedback (POST2) against the initial thresholds (PRE). (B) Same as (A) for the rotated–reversed feedback condition. Two stars represent a significant difference level of <0.05 (one tailed t-test, p = 0.04 after the first feedback; one tailed t-test, p = 0.03 after the second feedback). Also in this case all points, with the exception of one, fall below the equality line, showing that all subjects improved after feedback session. (C) Average tactile thresholds for the group of subjects with tactile, rotated and reverse–rotated feedback.
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Figure 4: (A) Results for the rotated feedback condition. The three data points in the left-hand graph represent the average results for the three bisection thresholds measured: the first one before any feedback (PRE), the second after the first feedback (POST1) and the third after the second feedback (POST2). The plot at right shows the thresholds for all subjects, plotting the thresholds after the second feedback (POST2) against the initial thresholds (PRE). (B) Same as (A) for the rotated–reversed feedback condition. Two stars represent a significant difference level of <0.05 (one tailed t-test, p = 0.04 after the first feedback; one tailed t-test, p = 0.03 after the second feedback). Also in this case all points, with the exception of one, fall below the equality line, showing that all subjects improved after feedback session. (C) Average tactile thresholds for the group of subjects with tactile, rotated and reverse–rotated feedback.

Mentions: We then examined the importance of spatial coherence for the tactile feedback: in one condition (rotated) we rotated the subject, but left the ordering of the speakers as before (so it was reversed with respect to the direction of sound); in the other we rotated the subject but reversed the order of tactile stimulators so they corresponded with the direction of sound (rotated–reversed). The results are shown in Figure 4, in the same format as Figure 3. In the rotated condition (Figure 4A), the feedback has no effect [repeated measures multi-comparison one way ANOVA F(2,14) = 0.24, p = 0.79] after the first (one tailed paired t-test, t4 = 0.34, p = 0.37) and nor after the second training (one tailed paired t-test, t4 = 0.53, p = 0.3). However, in the rotated–reversed condition (Figure 4B), there was a significant improvement (repeated measures multi-comparison one way ANOVA F(2,20) = 3.38, p = 0.056) after the first (one tailed paired t-test, t6 = 2.17, p = 0.036) and after the second training (one tailed paired t-test, t6 = 2.3, p = 0.03), although less than when subjects faced the speakers (an average factor pre/post of 1.7 was obtained for the rotated and reversed condition while an average factor pre/post of 2.4 was obtained for the tactile condition). Also in this condition no change was observed for PSEs [repeated measures multi-comparison one way ANOVA F(2,20) = 0.87, p = 0.437] after the two feedback sessions (one tailed paired t-test, t6 = 1.23, p = 0.13 for the first feedback session and one tailed paired t-test, t6 = 1.5, p = 0.09 for the second feedback session). In order to check for tactile precision differences between groups we also measured the bisection task in the tactile modality (Figure 4C). No difference was found between subjects [repeated measures multi-comparison one way ANOVA F(2,20) = 0.49, p = 0.62]. Overall these results suggest that spatial correspondence is essential for the tactile feedback to improve auditory spatial localization.


Tactile feedback improves auditory spatial localization.

Gori M, Vercillo T, Sandini G, Burr D - Front Psychol (2014)

(A) Results for the rotated feedback condition. The three data points in the left-hand graph represent the average results for the three bisection thresholds measured: the first one before any feedback (PRE), the second after the first feedback (POST1) and the third after the second feedback (POST2). The plot at right shows the thresholds for all subjects, plotting the thresholds after the second feedback (POST2) against the initial thresholds (PRE). (B) Same as (A) for the rotated–reversed feedback condition. Two stars represent a significant difference level of <0.05 (one tailed t-test, p = 0.04 after the first feedback; one tailed t-test, p = 0.03 after the second feedback). Also in this case all points, with the exception of one, fall below the equality line, showing that all subjects improved after feedback session. (C) Average tactile thresholds for the group of subjects with tactile, rotated and reverse–rotated feedback.
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Related In: Results  -  Collection

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Show All Figures
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Figure 4: (A) Results for the rotated feedback condition. The three data points in the left-hand graph represent the average results for the three bisection thresholds measured: the first one before any feedback (PRE), the second after the first feedback (POST1) and the third after the second feedback (POST2). The plot at right shows the thresholds for all subjects, plotting the thresholds after the second feedback (POST2) against the initial thresholds (PRE). (B) Same as (A) for the rotated–reversed feedback condition. Two stars represent a significant difference level of <0.05 (one tailed t-test, p = 0.04 after the first feedback; one tailed t-test, p = 0.03 after the second feedback). Also in this case all points, with the exception of one, fall below the equality line, showing that all subjects improved after feedback session. (C) Average tactile thresholds for the group of subjects with tactile, rotated and reverse–rotated feedback.
Mentions: We then examined the importance of spatial coherence for the tactile feedback: in one condition (rotated) we rotated the subject, but left the ordering of the speakers as before (so it was reversed with respect to the direction of sound); in the other we rotated the subject but reversed the order of tactile stimulators so they corresponded with the direction of sound (rotated–reversed). The results are shown in Figure 4, in the same format as Figure 3. In the rotated condition (Figure 4A), the feedback has no effect [repeated measures multi-comparison one way ANOVA F(2,14) = 0.24, p = 0.79] after the first (one tailed paired t-test, t4 = 0.34, p = 0.37) and nor after the second training (one tailed paired t-test, t4 = 0.53, p = 0.3). However, in the rotated–reversed condition (Figure 4B), there was a significant improvement (repeated measures multi-comparison one way ANOVA F(2,20) = 3.38, p = 0.056) after the first (one tailed paired t-test, t6 = 2.17, p = 0.036) and after the second training (one tailed paired t-test, t6 = 2.3, p = 0.03), although less than when subjects faced the speakers (an average factor pre/post of 1.7 was obtained for the rotated and reversed condition while an average factor pre/post of 2.4 was obtained for the tactile condition). Also in this condition no change was observed for PSEs [repeated measures multi-comparison one way ANOVA F(2,20) = 0.87, p = 0.437] after the two feedback sessions (one tailed paired t-test, t6 = 1.23, p = 0.13 for the first feedback session and one tailed paired t-test, t6 = 1.5, p = 0.09 for the second feedback session). In order to check for tactile precision differences between groups we also measured the bisection task in the tactile modality (Figure 4C). No difference was found between subjects [repeated measures multi-comparison one way ANOVA F(2,20) = 0.49, p = 0.62]. Overall these results suggest that spatial correspondence is essential for the tactile feedback to improve auditory spatial localization.

Bottom Line: Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially congruent.Our results suggest that the tactile system can be used to recalibrate the auditory sense of space.These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality.

View Article: PubMed Central - PubMed

Affiliation: Robotics Brain and Cognitive Sciences Department, Istituto Italiano di Tecnologia Genoa, Italy.

ABSTRACT
Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014). To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds before and after training, either with tactile feedback, verbal feedback, or no feedback. Audio thresholds were first measured with a spatial bisection task: subjects judged whether the second sound of a three sound sequence was spatially closer to the first or the third sound. The tactile feedback group underwent two audio-tactile feedback sessions of 100 trials, where each auditory trial was followed by the same spatial sequence played on the subject's forearm; auditory spatial bisection thresholds were evaluated after each session. In the verbal feedback condition, the positions of the sounds were verbally reported to the subject after each feedback trial. The no feedback group did the same sequence of trials, with no feedback. Performance improved significantly only after audio-tactile feedback. The results suggest that direct tactile feedback interacts with the auditory spatial localization system, possibly by a process of cross-sensory recalibration. Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially congruent. Our results suggest that the tactile system can be used to recalibrate the auditory sense of space. These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality.

No MeSH data available.