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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.


Related in: MedlinePlus

(A,B) Psychometric functions of two example subjects, plotting proportion of trials where the middle sound is judged closer to the right-hand one, as a function of the position of this sound. The data were fit with cumulative Gaussian error functions, whose mean (50% point) gives the “point of subjective equality” (PSE) and steepness (SD) the estimate of threshold. Black data and curve are taken before feedback, the dark gray symbols after the first tactile feedback session and the light gray after the second tactile feedback session. Steeper psychometric functions suggest higher auditory precision. (C) Average PSEs measured before any feedback (PRE), after the first feedback session (POST1) and after the second feedback session (POST2). (D) PSEs after the second feedback session (POST2) against the initial PSEs (PRE).
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Figure 2: (A,B) Psychometric functions of two example subjects, plotting proportion of trials where the middle sound is judged closer to the right-hand one, as a function of the position of this sound. The data were fit with cumulative Gaussian error functions, whose mean (50% point) gives the “point of subjective equality” (PSE) and steepness (SD) the estimate of threshold. Black data and curve are taken before feedback, the dark gray symbols after the first tactile feedback session and the light gray after the second tactile feedback session. Steeper psychometric functions suggest higher auditory precision. (C) Average PSEs measured before any feedback (PRE), after the first feedback session (POST1) and after the second feedback session (POST2). (D) PSEs after the second feedback session (POST2) against the initial PSEs (PRE).

Mentions: Auditory spatial precision was measured by a bisection technique. Three brief sounds (500 Hz, 75 ms duration, 60 dB SPL at the subject) were presented successively at 500 ms intervals in three different positions. The first sound was always positioned at –17.5°, the third at +17.5°, and the second at an intermediate position determined by the QUEST adaptive algorithm (Watson and Pelli, 1983), which estimates point of subjective equality (PSE) after each response, and places the next trial near that estimate. To ensure that a wide range of positions was sampled, that estimate was jittered by a random amount, drawn from a Gaussian distribution of space constant 17.5°, and the nearest speaker to that estimate chosen. Subjects reported verbally whether the second sound was closer to the left (speaker 1 at –17.5°) or right sound (speaker 9 at +17.5°). To ensure that a wide range of positions was sampled, that estimate was jittered by a random amount, drawn from a Gaussian distribution of space constant 17.5°, and the nearest speaker to that estimate chosen. Each subject performed 100 trials for each measure of threshold. The proportion of rightward responses was plotted as a function of the speaker position, and the data fit with a cumulative Gaussian function (see Figure 2) by means of the maximum likelihood method to estimate both PSE (given by the mean) and threshold (SD). The space constant (σ) of the fit was taken as the estimate of threshold indicating precision for the bisection task.


Tactile feedback improves auditory spatial localization.

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

(A,B) Psychometric functions of two example subjects, plotting proportion of trials where the middle sound is judged closer to the right-hand one, as a function of the position of this sound. The data were fit with cumulative Gaussian error functions, whose mean (50% point) gives the “point of subjective equality” (PSE) and steepness (SD) the estimate of threshold. Black data and curve are taken before feedback, the dark gray symbols after the first tactile feedback session and the light gray after the second tactile feedback session. Steeper psychometric functions suggest higher auditory precision. (C) Average PSEs measured before any feedback (PRE), after the first feedback session (POST1) and after the second feedback session (POST2). (D) PSEs after the second feedback session (POST2) against the initial PSEs (PRE).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4202795&req=5

Figure 2: (A,B) Psychometric functions of two example subjects, plotting proportion of trials where the middle sound is judged closer to the right-hand one, as a function of the position of this sound. The data were fit with cumulative Gaussian error functions, whose mean (50% point) gives the “point of subjective equality” (PSE) and steepness (SD) the estimate of threshold. Black data and curve are taken before feedback, the dark gray symbols after the first tactile feedback session and the light gray after the second tactile feedback session. Steeper psychometric functions suggest higher auditory precision. (C) Average PSEs measured before any feedback (PRE), after the first feedback session (POST1) and after the second feedback session (POST2). (D) PSEs after the second feedback session (POST2) against the initial PSEs (PRE).
Mentions: Auditory spatial precision was measured by a bisection technique. Three brief sounds (500 Hz, 75 ms duration, 60 dB SPL at the subject) were presented successively at 500 ms intervals in three different positions. The first sound was always positioned at –17.5°, the third at +17.5°, and the second at an intermediate position determined by the QUEST adaptive algorithm (Watson and Pelli, 1983), which estimates point of subjective equality (PSE) after each response, and places the next trial near that estimate. To ensure that a wide range of positions was sampled, that estimate was jittered by a random amount, drawn from a Gaussian distribution of space constant 17.5°, and the nearest speaker to that estimate chosen. Subjects reported verbally whether the second sound was closer to the left (speaker 1 at –17.5°) or right sound (speaker 9 at +17.5°). To ensure that a wide range of positions was sampled, that estimate was jittered by a random amount, drawn from a Gaussian distribution of space constant 17.5°, and the nearest speaker to that estimate chosen. Each subject performed 100 trials for each measure of threshold. The proportion of rightward responses was plotted as a function of the speaker position, and the data fit with a cumulative Gaussian function (see Figure 2) by means of the maximum likelihood method to estimate both PSE (given by the mean) and threshold (SD). The space constant (σ) of the fit was taken as the estimate of threshold indicating precision for the bisection task.

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.


Related in: MedlinePlus