The role of animacy in spatial transformations

982 Spatial perspective taking is the ability to represent aspects of the spatial environment as if from an alternative viewpoint. Perspective taking is useful in a variety of situations, including reasoning about others’ goals and intentions (Decety & Grèzes, 2006; Piaget & Inhelder, 1956; Vogeley et al., 2004), understanding others’ actions (Tversky, Lee, & Mainwaring, 1999), judging the visibility and relative location of objects (Michelon & Zacks, 2006), navigation (Kozhevnikov, Motes, Rasch, & Blajenkova, 2006), and using language (Traxler & Gernsbacher, 1993). For example, when asked to describe the layout of an apartment, speakers naturally adopt the viewpoint of a hypothetical visitor (Linde & Labov, 1975). Users of spoken and sign languages ubiquitously perform perspective taking, so that a speaker or signer presents information from the point of view of their conversational partner (Emmorey, Tversky, & Taylor, 2000; Schober, 1993). Humans sometimes engage in social interactions with other species, such as pets and farm animals (Hare & Tomasello, 2005), and, in such cases, they may use perspective taking as a means to understand an animal’s behavior. One way in which people may adopt novel perspectives is by imagining that their own body is in a different location, which can be considered to be an imagined spatial transformation. For example, if you wished to tell a friend that they have a smudge on the left side of their face, you could imagine yourself standing in their position and then determine whether the smudge would be on the left or the right side of their face as if it were your own. We will refer to imagining that you are in a different location or orientation as a perspective transformation. Perspective transformations can be distinguished from object-based transformations, in which one imagines that an object is in a different location or orientation. Returning to the example of the friend with a smudge on their left cheek, an object-based transformation strategy for this perspectivetaking task would be to imagine rotating the friend’s body into alignment with one’s own body. For judgments about others’ bodies, this is less intuitive than is the perspective transformation strategy for a majority of observers (Zacks & Tversky, 2005), but the situation might be different if one were making judgments about a statuette on a desk rather than about a life-sized animate person. Slightly more formally, both perspective and objectbased transformations are transformations in which the correspondence between spatial reference frames is updated. A spatial reference frame locates things in space. Reference frames differ in the referent with respect to which the target thing is located. Egocentric reference frames locate things relative to one’s self. Object-centered reference frames locate things relative to the intrinsic structure of an object. Environmental reference frames locate things relative to the encompassing spatial environment. For example, a viewer looking at the webcam on a laptop computer could describe it as being in front of the viewer (egocentric), at the top of the computer (object centered), or in the corner of the room (environmental). (For a more detailed discussion of spatial reference frames, see McCloskey, 2001.) In a perspective transformation, one’s egocentric reference frame is updated relative to the The role of animacy in spatial transformations