From silk to sand: Multiple dimensions of perceived softness

From silk to sand: Hand explorations are determined by the characteristics of the perceptual space of real-world materials Perceiving mechanical properties of objects, i.e., how they react to physical forces, is a crucial ability in many aspects of life, from choosing an avocado to picking your clothes. There is, a wide variety of materials that differ substantially in their mechanical properties. For example, both, silk and sand deform and change shape in response to exploration forces, but each does so in very different ways. Studies show that the haptic perceptual space has multiple dimensions corresponding to the physical properties of textures, however in these experiments the range of materials or exploratory movements were restricted. Here we investigate the perceptual dimensionality in a large set of real materials in a free haptic exploration task. Thirty-two participants actively explored deformable and non-deformable materials with their hands and rated them on several attributes. Using the semantic differential technique, video analysis and linear classification, we found four haptic dimensions, each associated with a distinct set of hand and finger movements during active exploration. Taken together our findings suggest that the physical, particularly the mechanical, properties of a material systematically affect how it is explored on a much more fine-grained level than originally thought. The folder contains raw data related to video event coding of 5 raters: R1_20180820.txt R2_14082018.txt R3_14082018.txt R4_20180610firstlist55.txt R5_20180610firstlist64v2.txt Same data are also shared in Matlab format after deleting unnecessary information such as file paths or fps: a.mat, h.mat, o.mat, s.mat, v.mat Ethogram file contains exploratory procedure names and materials file contains material names. Matlab files include codes for calculating inter-rater reliability (plot_correlate_EP_permaterial.m), resulting data for inter-rater reliability (IRR_overall_corrcoeffs.mat, IRR_permaterial_corrcoeffs.mat). We also include scripts to plot timelines and EP frequencies, plot_timelines_materials_alex.m and plot_durations_material_meansub_alex.m respectively. Finally, the script for classification from Mathworks Inc. uses built-in Matlab functions, we include our script where we only changed variable names (sort_svmdata4.m).