Thomas Parr
Institute of Neurology, University College London. Nuffield Department of Clinical Neurosciences, University of Oxford
Functionalist What matters is the organisation of the processing, not the material
Thomas Parr is a clinician and computational neuroscientist at University College London and the University of Oxford. With Giovanni Pezzulo and Karl Friston, he co-authored Active Inference: The Free Energy Principle in Mind, Brain, and Behavior (MIT Press, 2022), the definitive mathematical synthesis of discrete and continuous active inference across perception, action planning, and neuromodulatory precision control.
In September 2026, Parr and Karl Friston published “The phantastic organ” in Frontiers in Psychology (doi:10.3389/fpsyg.2026.1901293). Taking its title from the Greek phantastikos, the capacity to produce mental images and constructive appearances, the paper argues that the brain is an inside-out generative engine whose perceptual experience is a controlled endogenous fantasy constrained at the sensory boundary by precision-weighted prediction errors.
Parr’s clinical research on visual neglect, neuromodulation, and thalamic routing grounds this functionalist architecture in neuroanatomy. By mapping acetylcholine, noradrenaline, and dopamine onto specific precision parameters in hierarchical message passing, his work specifies the exact control variables a synthetic or emulated cognitive architecture must regulate to sustain coherent perceptual synthesis.
Known for. Active Inference: The Free Energy Principle in Mind, Brain, and Behavior (2022), computational neuropsychology of visual neglect and precision control, The phantastic organ (2026)
Coverage on this site
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Thomas Parr is listed with the other functionalists and computationalists, who hold that what matters is the organisation of the processing, not the material. The theory family behind that position is set out in the index of consciousness theories. Every researcher covered on this site is indexed in the directory of consciousness researchers.