Is action-guiding vision cognitively impenetrable?

Is action-guiding vision cognitively impenetrable? Bence Nanay (bence.nanay@ua.ac.be or bn206@cam.ac.uk) Centre for Philosophical Psychology, D 413, Grote Kauwenberg 18, Antwerp, 2000 Belgium and Peterhouse, Cambridge University, Cambridge, CB2 1RD, UK Goodale 1995, 2008, Goodale & Milner 2004, Rizzolatti & Matelli 2003). For many philosophers and psychologists, the last refuge of the cognitive impenetrability thesis is unconscious action-guiding vision. My aim is to argue that action-guiding vision is not cognitively impenetrable and arguments that suggest otherwise rely on an unjustified identification between action-guiding vision and dorsal vision – a functional and an anatomical way of describing the mind. The examination of these arguments show the importance of making a distinction between the functional and the anatomical level when addressing the problem of cognitive penetrability. Abstract The aim of this paper is to argue that action-guiding vision is not cognitively impenetrable and arguments that suggest otherwise rely on an unjustified identification between action- guiding vision and dorsal vision – a functional and an anatomical way of describing the mind. The examination of these arguments show the importance of making a distinction between the functional and the anatomical level when addressing the problem of cognitive penetrability. Keywords: Cognitive impenetrability; dorsal vision; action- guiding vision; perception and action; multimodal perception; top-down influences on perception The impenetrability of conscious versus unconscious perception Action-guiding vision There are notorious ambiguities in the formulation of the cognitive penetrability debate. Some of these has been acknowledged and (more or less) resolved, like the one about the various senses in which a mental process could be considered to be cognitively penetrable (Fodor 1983). A seemingly simpler but often unacknowledged ambiguity is not about the predicate of the claim that perception is cognitively impenetrable, but its subject. It seems that when philosophers and psychologists talk about the cognitive penetrability or impenetrability of perception, they mean very different things by ‘perception’. Some (mostly philosophers) mean conscious perceptual experience (Lyons 2011, Siegel 2011), some others (mostly psychologists) mean perceptual processes in general, conscious or unconscious. As perception can be conscious or unconscious, even if it is true that conscious perceptual experience is cognitively penetrable (or impenetrable), this should not be generalized to unconscious perception and, as a result, to perception in general. This distinction is especially important if we consider the following possibility. Many philosophers and psychologists now assume some version of the claim that conscious experiences are cognitively penetrable. But this leaves open the question whether unconscious perceptual states are cognitively penetrable. More specifically, this leaves open whether the most compelling cases for unconscious perceptual processes, namely, the ones that guide our goal- directed actions, are cognitively impenetrable. According to a more and more influential view, the unconscious perceptual, or, more precisely, visual, processes that guide our goal-directed actions, which we can call ‘action-guiding vision’ is cognitively impenetrable (Milner 2008, Goodale & Wolf 2009, Raftopoulos 2001, 2005, Norman 2002, Goodale 2011, Jacob & Jeannerod 2003, Jeannerod & Jacob 2005, Jacob 2005, Milner & I call ‘action-guiding vision’ those, mainly unconscious, processes in visual perception that help us to perform the goal-directed movements of our actions. But why should we assume that there is such processes? And why should we think that they are unconscious? The main reason for thinking that there is such a thing as unconscious action-guiding vision is that in certain circumstances, our conscious visual experiences represent the world differently from the way the perceptual processes that help us to perform goal-directed actions do (see, e.g., Loach et al. 2008, Xu et al. 2012). The most important examples for this comes from the study of optical illusions. A number of optical illusions mislead our perceptual experience but not (or much less) our action-guiding vision. One such example is the three dimensional Ebbinghaus illusion. The two dimensional Ebbinghaus illusion is a simple optical illusion. A circle that is surrounded by smaller circles looks larger than a circle of the same size that is surrounded by larger circles. The three dimensional Ebbinghaus illusion reproduces this illusion in space: a poker-chip surrounded by smaller poker-chips appears to be larger than a poker-chip of the same diameter surrounded by larger ones. The surprising finding is that although our perceptual experience is incorrect – we experience the first chip to be larger than the second one –, if we are asked to pick up one of the chips, our grip-size is hardly influenced by the illusion (Aglioti et al. 1995, see also Milner & Goodale 1995, ch. 6 and Goodale & Milner 2004). Similar results can be reproduced in the case of other optical illusions, like the Muller-Lyer illusion (Goodale & Humphrey 1998, Gentilucci et al. 1996, Daprati & Gentilucci 1997, Bruno 2001), the ‘Kanizsa compression illusion’ (Bruno & Bernardis 2002), the dot-in-frame illusion (Bridgeman et al., 1997), the Ponzo illusion