-
5 Dreaming, Default Thinking, and Delusion
- The MIT Press
- Chapter
- Additional Information
5 Dreaming, Default Thinking, and Delusion In this chapter we pursue the idea that the often-remarked, but not well-explained, similarity between dreaming and delusion results from the fact that they are both states characterized by activity in the default system unsupervised by decontextualized processes. We give a mechanistic and a cognitive explanation of similarities and dissimilarities between delusions and dreams. The mechanistic explanation adapts the AIM (Activation, Information , Mode) model of dreams and delusions developed by Hobson and collaborators. The cognitive explanation shows how automatic and controlled processes degrade in different ways when unsupervised in virtue of differences in cognitive architecture. That explanation distinguishes feature and context binding . Binding here refers to the integration of elements of a representation . Feature binding refers to the construction of an integrated perceptual or quasi-perceptual representation and contextual binding to the organization of such representations into a coherent metacognitive structure such as a narrative or theoretical explanation. Feature binding is a relatively modular process implemented in localized neural circuits whose processing properties are fairly rigid. In general, feature binding is a 90 Chapter 5 task performed by weight-based processing systems that automatically assemble representational elements according to procedures standardized by evolution or in development. Because these processes have fairly rigid architectures, they tend not to disintegrate unless their neural substrates are damaged. Context binding is intrinsically a more unstable process because it is by its nature flexible and open-ended. It requires active maintenance of transient distributed circuits and constant top-down supervision. One form of context binding relevant to delusions is the binding of simulations into the narratives and narrative fragments of mental time travel. Delusions are a form of context binding in which subjects produce a default thought subjectively adequate to experience. That thought is not the result of an attempt to confirm an empirical hypothesis. It is an untested (because unsupervised) default thought. We develop these ideas by discussing an example of delusion-like phenomena in dreams—the experience of hyperfamiliarity—and suggest that it results from a similar feature-binding anomaly to one that occurs in a waking state in the Fregoli delusion. In dreams, however, this anomaly does not lead to delusion because in dreaming the default network is not configured to produce a narrative context for such anomalous experiences. 5.1 Dreaming and the Default Mode Network The default system evolved as the first stage in the transformation of automatism to agency. It allows humans to rehearse alternatives before committing to action. These rehearsals typically take a narrative form. The production and consumption of these narratives is in turn supervised by a higher level of decontextualized [18.206.13.112] Project MUSE (2024-03-29 02:22 GMT) Dreaming, Default Thinking, and Delusion 91 cognitive processing. This supervision can take the form of testing narrative elements for consistency and veridicality or evaluation of competing narratives for accuracy or utility. When dorsolateral systems required to represent high-level goals and evaluate default narratives against them are inactive, the default network reverts to its default state: the production of subjectively adequate narratives. When there is no goal or end point for the narrative, it tends to degrade into the random association of default representations. This is sometimes put in terms of the absence of attentional control in default thinking. A simulation process that starts with a specific goal may meander as top-down attentional control wanes. It is for this reason that dreaming represents a state of unsupervised default processing. As well as the absence of top-down control, the default processing in dreaming is characterized by the absence of organizing input from the sensory periphery, which leaves the default network entirely at the mercy of endogenous activation by subcortical inputs: Dreams can be seen as a unique and more fully developed form of mindwandering , and therefore as the quintessential cognitive simulation. They are the quintessential cognitive simulation not only because they have elaborate storylines that are often enacted with exquisite sensory, motor, and cognitive involvement, with some dreams unfolding over a period of several minutes to half an hour or more. There is also the striking fact that they are usually experienced as real while they are happening . (Domhoff 2011, 1172) This is one reason that people have drawn a parallel between dreaming and delusion. John Nash, for example, said of his delusional states: “It’s kind of like a dream. In a dream it’s typical not to be rational” (Nash n.d.). While...