Salient Properties in Bimanual Haptic Volume Perception: Influence of Object Shape, Finger Pair, and Schizotypal...

Bimanual haptic volume perception refers to somatosensory access to volume information through both hands, and the characteristics that influence this perception remain unclear. This article investigated the influence of target object shapes and finger pairs on bimanual haptic perception; in addition, associations of bimanual haptic impairment and schizotypal features in nonpsychotic individuals were investigated. Twenty blindfolded participants bimanually discriminated volume variations in regular solid objects under different shape (tetrahedron, cube, or sphere) and finger pair (high- or low-sensitivity pairs) conditions using a newly developed bimanual haptic volume presentation device. Discrimination thresholds were then associated with schizotypal traits using the Chinese version of the Schizotypal Personality Questionnaire. Target object shape and finger pairs significantly influenced bimanual haptic volume perception. Volume discrimination thresholds were significantly higher with the tetrahedron stimuli than the cubic or spherical stimuli in high-sensitivity pair conditions, but no significant differences among shapes were found in low-sensitivity pair conditions. Moreover, volume discrimination thresholds with high-sensitivity pairs were correlated with the paranoid score of the schizotypal personality questionnaire. The findings provide initial evidence toward understanding the nature of bimanual haptic volume perception, including the properties of objects, individuals, and object-individual interfaces.