In developing a Virtual Reality simulation for learning breast palpation, one of critical aspects is real-time visualization of breast phantom deformation during palpation. Available models are either offline ones using Finite Element Method (FEM) analysis with considering some material parameters of deformable objects; or real-time ones with difficulties of balancing between this consideration and realistic visualization. For visual perception of breast phantom deformation, we used a real-time model with an inside pressure to keep the volume of the breast phantom constant. On a meshed breast phantom, we compared the displacements of vertices governed by the real-time model with those governed by its FEM counterpart for four different distributions of contact force. To satisfy visual perception of breast phantom deformation, we examined the comparison by utilizing the statistical methods of ANOVA and Bland and Altman agreement. The results revealed that the displacements of vertices governed by the real-time model are in agreement with those by its FEM counterpart for each distribution of contact force. This observation indicates the potential of our real-time model for visualizing breast phantom deformation during palpation.