Human perception is not always a faithful representation of the physical world, as it can be significantly biased by the surrounding context. For example, the orientation of a vertical grating is perceived away from that of the surrounding gratings, and a sofa embedded in a living-room setting is easier to identify than the same sofa in an African plains background. The contextual effect, although taking into consideration the low-level physical properties or the semantic association between objects, has so far been rarely explored in the social domain.