Passive Method for Eliciting Softness Impressions Using Soap Bubbles

This study explored soap-bubble collisions with human skin as a passive approach to eliciting softness impressions. Although prior work has shown that perceived softness is associated with increased contact area during deformation, this relationship has not been examined in the context of soap bubbles. This study controlled bubble behavior by modifying the surface condition of the palm and analyzed the effect of the temporal relationship between contact and rupture sensations on softness perception. In an observational experiment using cowhide as a surrogate for human skin, the time interval from initial contact to rupture varied with surface condition. Under a moderately moist condition produced by applying anhydrous ethanol, a modest delay between contact and rupture was observed. The same condition, when presented on the palm in a subjective evaluation, yielded the highest softness ratings. These results suggest that the temporal relationship between contact and rupture sensations contributes to softness perception.