Raúl Arrabales Moreno

Cognitive Neuroscience – Artificial Intelligence – Machine Consciousness

Multiple Draft Model

The Multiple Draft Model (MDM) introduced by Dennett (1991), uses the editorial review metaphor to describe the cognitive processes of consciousness.

In this domain, coalitions of unconscious processors suffer a reiterative edition and review process (producing a number of drafts). The last version obtained is the one that appears as a conscious content of the mind.

Dennett argues there is nothing such a central command center in the brain where some sort of director controls the self. On the contrary, all activity is developed by distributed sub-processes concurrently created in the brain. This could be seen as opposing Baars’ approach, where there is a central representation place for conscious contents (the spotlight in working memory). Actually, both accounts are materialistic, because they reject the Cartesian dualism (Baar’s spotlight does not correspond to a concrete point in the brain). However, materialism is more present in Dennetts’ account as there is not a conceptual central point. Additionally, Dennett explicitly rejects dualism, and state that it is the mere result of the ignorance and scientific incapability of some authors.

Staying away from the philosophical debate, and focusing on the functional standpoint, we can analyze how Dennett defines the conscious self as the owner of a point of view. Given that the brain has a limitation on the quantity of information that it can process at any given time, a conscious mind is an observer that collect a partial subset of the information coming from the environment. This information is not processed serially, in fact, the brain has a number of specialized modules that process this information in parallel. What Dennett adds to this view is that the information is continuously being revised and modified in order to adapt to the new incoming information. This explains our capacity of being simultaneously conscious of perceptions that take different time in being processed. (For instance, visual stimuli take more processing time than auditory ones).  What we consciously experience is the result of multiple interpretative processes. Many of the drafts that are built are discarded and disappear as time goes by. Only one version remains and takes part in the final narrative process, being stored in memory. These contents fixed in memory, which in turn affect consciousness, are also affected by the reviewing process. Given that a central reviewer that gives sense to the narration does not exist, there is no concrete instant in time when content becomes conscious.

Dennett argues that consciousness is executed in some sort of virtual machine modulated by cultural learning that runs on the brain parallel hardware. This virtual machine installs in the brain is a set of ‘mind habits’, which are not visible at a neuron-anatomic level. The successful deployment of such conscious machinery is possible thanks to a number of micro-dispositions produced due to brain plasticity.

To sum up, Dennetts’ proposed model implies that the conscious version of our thought is the winner of a continuous reviewer and change process. The factors that determine which will be the final official version at any given time can be diverse. For instance, during a rage episode, the coalitions of processors presenting more furious versions will be the winners. Anyhow, the brain will be always looking for an explanation that plausibly adapts to perception, but it doesn’t need to actually correspond to reality.

Raúl Arrabales

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