Perception of fluids with diverse rheology applied to the underarm versus forearm skin.

Little is known about the tactile-perceptual structure of fluids. Therefore, ten fluids with diverse, characterized rheologies were rated by 16 females, on 27 sensory attributes (e.g., "slippery") and 14 emotional attributes (e.g., "enjoyable") via five-point categorical scales. Fluids were assessed against the volar forearm and underarm, sites that commonly experience contact with fluids during the use of personal care products. Application of fluids was either by the participant to their own body ("self-applied") or by the experimenter to the participant's body ("experimenter-applied"). Separate factor analyses of the sensory and emotional attributes for different body sites and modes of touch suggested approximately the same factorial structure in each case. Four general sensory factors emerged, labeled Lubricating, Textured, Silken, and Viscous, and two emotional factors, Comfortable and Arousing. These factors resembled those from equivalent work that used solid materials as stimuli, emphasizing that despite the differences in perceptual structure between fluid-coated and dry, solid surfaces, different body sites, and modes of touch influence the perception of fluid and dry stimuli similarly. As expected, fluids varied widely in how they scored on the factors. Site-wise differences were found, whereby stimuli assessed against the forearm were rated as more Lubricating, less Textured, more Silken, and more Comfortable than they were against the underarm. Self-applied touch was less Comfortable than experimenter-applied. The physical and perceptual were linked insofar as greater measured viscosity at low shear rates was associated with perceptions of cold and wet, whereas at high shear rates, greater viscosity was associated with greater perceived thickness.