[1]
My discussion is restricted to spatial perspectival phenomena; I omit discussion of the respects in which temporal experience may be perspectival. This is mostly for the sake of simplicity. However, there is good reason to think that we represent time in a manner that is asymmetrically dependent upon the ways in which we represent space (Boroditsky 2000; Casasanto & Boroditsky 2008). Addressing issues concerning the structure of spatial experience first may thus be prudent.
[2]
This notion is intended to capture the idea that there is a point of “origin” to the so-called line of sight (which is not so much a line as an angle). This corresponds to perhaps the earliest documented notion of perceptual perspective, associated with what Euclid and Ptolemy respectively called the “visual pyramid” and “visual cone”, where the apex (origin) of the pyramid or cone is at the eye and the base at the object (Howard 2012).
[3]
I do not intend the following to be exhaustive. Moreover, although all of the perspectival phenomena that I discuss are visual, I do believe that each of the forms of perspectival structure that I describe also characterises perspectival experience in haptic perception.
[4]
The most I intend to claim here is that these forms of perspectival structure are non-identical. Perhaps the origin of a given sensory field, the centre of a given egocentric frame of reference, and the focal point of a given sensory flow field could occupy the same location under some description. However, this certainly need not always be the case. Moreover, each form of perspectival structure will present the objects of perceptual experience as related to the subject of experience in different ways, e.g., as only partially visible, as straight ahead, or as in one’s way. Below I will suggest various ways in which these might be selectively manipulated, but I do not intend to make the case that forms of perspectival structure can be dissociated from one another.
[5]
When a perspective is explicit, the location of the origin, centre, or focal point is part of the content of the experience. Any beliefs that the subject has about the location in question do not go beyond the content of that experience (cf. Peacocke 1999, p. 265). The experience may represent the location in question in an imprecise or wholly incorrect manner; the subject’s beliefs will be correspondingly imprecise or incorrect. Implicit perspectives structure experience without being part of the content of experience. I leave it open whether implicit perspectives are nevertheless experienced qua structural feature, or whether, for example, they are merely formal structures that determine the ways in which things are experienced, without themselves being experienced. Issues like this are difficult to evaluate, but for discussion see Alsmith (2012).
[6]
This would be, I take it, as close as practically possible to viewing the two avatars at the same time, given limitations in the field of view.
[7]
Peacocke writes: “The use of a particular set of labeled axes in giving part of the content of an experience is not a purely notational or conventional matter. The appropriate set of labeled axes captures distinctions in the phenomenology of experience itself. Looking straight ahead at Buckingham Palace is one experience. It is another to look at the palace with one's face still toward it but with one's body turned toward a point on the right. In this second case the palace is experienced as being off to one side from the direction of straight ahead, even if the view remains exactly the same as in the first case” (1992, p. 62). Assuming that Peacocke’s prediction is correct, then in this example changes in the egocentric perspectival structure of visual experience follow changes in the orientation of the torso. By misaligning the torso from the direction of the gaze, one discerns that (in the case as described) the appropriate set of labelled axes centre upon the torso. In the paradigm described in experiment 3, both head and torso may be misaligned with the individual’s gaze. This makes it possible to determine the contribution of both head- and torso-centred frames of reference to the individual’s egocentric perspectival experience of a given location. It would then be possible to discern whether, for the egocentric perspectival experience of a given location: (i) the appropriate set of axes centre on the torso; (ii) the axes centre on the head; (iii) both sets of axes make relative contributions to the structure of the experience.
[8]
It is perhaps worth noting that by “congruent” I intend the more general sense of the term, as often used in describing the design of behavioural studies, the meaning of which is equivalent to “in agreement”. I do not intend the more specific geometrical sense of the term, which expresses identity of a certain kind, typically of form.
[9]
The authors write that “deviations of 5◦, 10◦, and 15◦ lead to many erroneous self-attributions”, found to be “decreasing in magnitude with increasing angular deviation” (Kannape et al. 2010, p. 1631). As broached above, one explanation of this pattern would be that deviations below 15◦ all fall (to a greater or lesser degree) within the phenomenal groove of the action specified by the task.