In this section I would like to consider how conscious experience might relate to the PP framework. In particular, I suggest that there is a convergence between a priori descriptions of consciousness, on one hand, and the structure of information processing according to PP on the other.[3] I will not remark on the way in which PP relates to some well-known issues in the study of consciousness, such as the hard problem or the explanatory gap. It is not clear to me that PP has anything new to contribute to these topics. Nor will I make any claims about which existing theories of the neural basis of consciousness fit best with PP, although I suspect there is some interesting work there to be done.
My main concern here is in the structure of conscious experience, of visual experience in particular. Here I adopt a strategy recommended by Thomas Nagel (1974), and David Chalmers (1996, pp. 224–225). Nagel puts the idea nicely, “[…] structural features of perception might be more accessible to objective description, even though something would be left out” (1974, p. 449, cited in Chalmers 1996, pp. 382 f.). The strategy has been implemented, in fact, using Marr’s theory of vision—the theory that, as Clark puts it, PP turns upside down. Ray Jackendoff (1987, p. 178) and Jesse Prinz (2012, p. 52) have both emphasized the structural similarities between conscious visual experience and Marr’s 2.5 dimensional sketch. Visual phenomenology is not a flat two-dimensional surface, because we see depth. But neither is visual phenomenology fully three-dimensional, because we cannot see the hidden sides of objects. Marr’s 2.5 dimensional representation captures the level in-between two and three dimensional representation that seems to correspond to our visual phenomenology; it captures Hume’s insight that visual experience is perspectival: “The table, which we see, seems to diminish, as we remove farther from it […]” (1993, p. 104).
As Hume emphasized the perspectival nature of visual experience, Kant famously emphasized the temporal nature of experience in the second section of the Transcendental Aesthetic: “Time is a necessary representation (Vorstellung), which lays at the foundation of all intuitions” (1781/1887/1998, A31). In an elegant synthesis of these two features of visual experience, Edmund Husserl suggested that the general structure of visual experience is one of anticipation and fulfillment:
Every percept, and every perceptual context, reveals itself, on closer analysis, as made up of components which are to be understood as ranged under two standpoints of intention and (actual or possible) fulfillment. (Logical Investigation, VI §10 1900, Findlay trans., 1970)
In this passage from his early work, Husserl writes of “intention and fulfillment,” but he later replaced “intention” with “anticipation” when dealing with perception.[4]
The main point is fairly straightforward: we perceive properties by implicitly anticipating how the appearances of those properties will change as we move (or as the objects move). Husserl’s proposal accommodates the perspectival character of experience because it addresses the question of how we perceive objective properties despite being constrained to one perspective at a time. And it accommodates the temporal nature of experience because anticipation is always future-directed.
Here is not the place to enter into the details of the thesis that the general structure of conscious experience is one of anticipation and fulfillment (see my 2013 for some of these details), but I should add one more point. As both Husserl (1973, p. 294) and Daniel Dennett (1991, Ch. 3) have noted, peripheral vision is highly indeterminate.[5] Also, as we explore our environment we experience a continuous trade off between determinacy and indeterminacy. As I lean in for a closer look at one object, the other objects in my visual field fade into indeterminacy. In order to account for this feature of experience, we can note that visual anticipations have various degrees of determinacy.6
Now let us return to PP. If Hume provides the philosophy of perception for Marr’s theory of vision, then Husserl provides the philosophy of perception for PP. The structural similarities should be apparent. The predictive brain underlies the essentially anticipatory structure of perceptual awareness. Degrees of determinacy are encoded probabilistically in our generative models (Clark 2013; Madary 2012b). Action and perception are tightly linked (Clark this collection, p. 9) as self-generated movements stir up new perceptual anticipations.
Many readers will see a connection between the thesis of anticipation and fulfillment, on one hand, and the sensorimotor approach to perception (O’Regan & Noë 2001; Noë 2004) on the other. Overall, there is significant thematic overlap between the two (Madary 2012a, p. 149). As Seth (2014) has argued, many of the central claims of the sensorimotor approach can be incorporated into the PP framework.7 This synthesis offers impressive explanatory power, bringing the standard sensorimotor experimental evidence (reversing goggles, change blindness, selective rearing) together with the theoretical neuroscience of PP. The explanatory power is even more impressive if I am correct that PP reflects the general structure of visual phenomenology, where predictive processing corresponds to perceptual anticipations and probabilistic coding corresponds to experienced indeterminacy.