Fig 1.
Experiment demonstration of this study (forward, blue mappings) and previous study [37] (inverse, yellow mappings).
Table 1.
Summary of experiments conducted in the study.
Fig 2.
Experiment webpage for frequency-to-visual distance matching.
A user-adjustable dial on the left is rotated by the participant to switch the image on the right until its distance matches the auditory or vibrotactile frequency being given to the participant.
Fig 3.
Example image stimuli at different positions.
(a) Human at 1 m position;(b) Human at 4 m position; (c) Human at 8 m position; (d) Human at 12 m position; (e) Coat stand at 1 m position; (f) Coat stand at 4 m position; (g) Coat stand at 8 m position; (h) Coat stand at 12 m position.
Fig 4.
Perceived distance as a function of auditory or vibrotactile frequencies, example raw data responses from different participants.
(a) Experiment 1a, three patterns: negative, positive, and neutral. (b) Experiment 1b, three patterns: negative, positive, and neutral. (c) Experiment 2a, two patterns: negative, and neutral. (d) Experiment 2b, three patterns: negative, positive and neutral.
Fig 5.
Optimal number of clusters determined using the silhouette score.
For Experiment (a) 1a, (b) 1b, (c) 2a, (d) 2b - the silhouette score method was applied to identify the optimal K values for K-means clustering.
Fig 6.
Data partitioning into clusters.
For Experiment (a) 1a, (b) 1b, (c) 2a, (d) 2b respectively, K-means clustering was applied based on the optimal number of clusters (K) from Fig 5. Each marker represents a single participant.
Table 2.
Proportions of correlations across users.
Table 3.
Proportions of best-fitting models across users.
Fig 7.
Average , RMSE, and standard deviation of model fit across users.
(a) Negative correlation group in Experiment 1, (b) Positive correlation group in Experiment 1, (c) Negative correlation group in Experiment 2, (d) Positive correlation group in Experiment 2.
Fig 8.
Plot of representative function for each correlation group.
(a) Negative and positive correlation between auditory frequency and visual distance in Experiment 1. (b) Negative and positive correlation between vibrotactile frequency and visual distance in Experiment 2.
Fig 9.
Patterns illustrating the correlation between visual distance and frequency across audio and vibrotactile domains obtained from all experiments conducted in both the present (forward) and prior (inverse) studies [37].