An Empirically Motivated Theory of Visual Imagery in Memory and Imagination and its Relation to Vision
University of Nottingham
This article explores one way to develop Crane’s (2001, 2003, 2009) theory of the ‘Intentional Structure of Consciousness’ in terms of visual perception, memory and imagination. At the lower ‘sub-personal’ level of processing, it outlines the brain areas and cognitive functions that might underpin vision-like experiences such as: perception, hallucination and visualization. It then relates this to our higher level phenomenally experienced intentional vision-like states and suggests one way to link them together across these two levels of description. Hence it attempts an analysis of these prevalent mental states from either side of the signal to phenomenal gap and shows how vision and visual imagery might be closely related to one another, whilst still explaining certain crucial differences between them. One of the key features of Crane’s theory that will need to be addressed, is his tripartite division of consciousness into ‘subject- intentional mode-content’. Another is his appeal to the idea of ‘aspectual shape’, which explains how we can think of the same experience of an object or event (i.e. content) in different ways. The final feature to be explained is his suggestion that perception need not be a propositional attitude.
In order to achieve this I will first introduce and adopt the Kosslyn Model of vision and visual imagery (Kosslyn et al 2006). This yields a hybrid-depictive representational theory of the neuro-functional mechanisms that may underpin visual states such as: perception, hallucination, imagination and memory. This allows us to develop an approach where vision is based on non-propositional representations and hence need not necessarily be a propositional attitude. Also based on differences in how these mental states are processed we can explain Crane’s tripartite division of consciousness, with different intentional modes being partly defined by their causal history. Finally, depending on how these vision-like states are sometimes interpreted and ‘labelled’ propositionally, we can explain how the same perceptual or imagistic state can be thought of in different ways or under different ‘aspectual shapes’. Hence offering one plausible way to expand on and develop Crane’s intentional theory of consciousness at dual levels of description and by appealing to a mixed representational approach.
The style of the paper is to briefly introduce the necessary theories without defending them too thoroughly, since this is done elsewhere by the respective authors (see also King forthcoming). Therefore the main focus is to show how Crane’s intentional approach can be synthesised with the Kosslyn Model, in order to yield a fairly complete theory of our full range of vision-like experiences. It will also suggest that visual images can usefully be interpreted as offline simulations of online visual experiences, where an area of the visual cortex (called the visual buffer) is re-used ‘offline’ in visual memory and imagination. My theory also explains how these visual images can become labelled to represent events from different times and places. Hence also explaining how we can re-visualize events from the past and creatively imagine possible events in the future (i.e. an episodic thinking and mental time travel capacity).
Crane, T. (2001). Elements of Mind: An Introduction to the Philosophy of Mind. Oxford University Press
Crane, T. (2003). The intentional structure of consciousness. In Q. Smith & A. Jokic (eds), Consciousness: New Philosophical Perspectives. Oxford University Press
Crane, T. (2009). Is perception a propositional attitude? The Philosophical Quarterly, 59: 452–469
King, PR. (forthcoming). Spatio-Temporal Imagination: How We Visualize Other Times and Places. Springer (deadline Dec 2011) – adapted from my thesis where I mainly defend and develop an offline simulation interpretation of the Kosslyn Model.
Kosslyn SM, Thompson WL. & Ganis, G. (2006). The Case For Mental Imagery. Oxford Psychology Series