Action Is Enabled by Systematic Misrepresentations
According to active inference (which subsumes the framework of predictive processing), action is enabled by a top-down modulation of sensory signals. Computational models of this mechanism complement ideomotor theories of action representation. Such theories postulate common neural representations for action and perception, without specifying how action is enabled by such representations. In active inference, motor commands are replaced by proprioceptive predictions. In order to initiate action through such predictions, sensory prediction errors have to be attenuated. This paper argues that such top-down modulation involves systematic (but paradoxically beneficial) misrepresentations. More specifically, the paper first argues for the following conditional claim. If active inference provides an accurate computational description of how action is enabled in the brain, then action is enabled by systematic misrepresentations. Furthermore, it is argued that an inference to the best explanation provides reason for believing the antecedent is true: Firstly, active inference provides a crucial extension to ideomotor theories. Secondly, active inference explains otherwise puzzling phenomena related to sensory attenuation, e.g. in force-matching or self-tickling paradigms. Taken together, these reasons support the claim that action is indeed enabled by systematic misrepresentations. The claim casts doubt on the assumption that representations are systematically beneficial to the extent that they are true: if the argument in this paper is sound, systematically beneficial misrepresentations may lie at the heart of our neural architecture.
I am highly grateful to Jakob Hohwy for providing very detailed and helpful feedback on an earlier version of this paper. Some of the ideas present in this paper were presented in a talk I gave at a workshop in the context of the Carnap lectures in March 2014 in Bochum. I am grateful to the audience of that workshop, special thanks to the organizers Albert Newen and Tobias Schlicht, and to Peter Brössel and Daniel Dennett. A previous version of this paper was presented at the Journal Club of the theoretical philosophy group at Mainz University, organized by Thomas Metzinger; thanks to all participants. Another version was presented at Spindel 2014 in Memphis. Thanks to the organizer Shaun Gallagher, as well as to the audience of that conference. Thanks to two anonymous referees for providing a number of very helpful comments. Part of the work on this paper was supported by a scholarship of the Barbara Wengeler foundation.
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