 Recent accounts appealing to generative models and predictive processing (Clark 2013b; Hohwy 2013) suggest a new, unified account of perception, imagination, and dreaming. In these accounts, different mental states, including perception and action, embody different strategies of hypothesis testing and prediction error minimization. Perception is the attempt to model the hidden external causes of sensory stimuli; action involves keeping the internal model stable while changing the sensory input. Clark argues that on such a model,