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Abstract

The idea that faces are represented within a high-dimensional vector space has gained considerable experimental support both from physiological and perceptual studies. More generally, recent work has shown that the brain possesses a surprising acuteness in extracting such high-dimensional spaces from both visual and haptic stimuli. Here, we investigate the degree to which visual and haptic face spaces might be similar. For this, we created a face space consisting of 6 laser-scanned individual faces, their morphed average, 50-morphs between two individual faces, as well as 50-morphs of individual faces with the average, resulting in a set of 19 faces. We then gathered either visual or haptic pairwise similarity ratings of 3-D face masks from two groups of fifteen participants. Faces were explored 6 s visually, and 10 s haptically with one hand, respectively. Correlations between haptic similarity ratings were lower than between visual ones indicating the difficulty of the haptic task. Importantly, however, multidimensional scaling analyses showed that both modalities preserved critical topological relationships of the original space in a 3-D perceptual space. Our data demonstrates how the brain can extract high-dimensional shape properties of complex stimuli in both vision and haptics.