Researcher at a glance
- Affiliation: Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London (with Friston); later University of Oxford
- Orientation: Active inference; the free-energy principle; the Markov-decision-process formalism for discrete-state active inference and its neuroanatomy
Key contributions
- Co-author (with Friston and Pezzulo) of the systematising work on active inference — the discrete-state (Markov decision process) formulation, its message-passing implementation, and the mapping of belief-updating onto cortical/subcortical circuits.
- Applied active inference to attention, salience and oculomotor control, treating attention as precision-setting and as (covert) action — the basis of the 2019 account of Troxler fading and binocular rivalry.
- Worked on the computational anatomy of visual neglect and of consciousness, reading pathologies of awareness as aberrant inference rather than lost representation.
Key papers
- Parr et al. (2019) — Parr, Corcoran, Friston & Hohwy (2019), Neuroscience of Consciousness — attention as covert action; perceptual fading and rivalry as active inference.
- Parr, T. & Friston, K. J. (2018). The anatomy of inference: generative models and brain structure. Front. Comput. Neurosci.
- Parr, T., Pezzulo, G. & Friston, K. J. (2022). Active Inference: The Free Energy Principle in Mind, Brain, and Behavior. MIT Press.
Connections
- Debates: inferential?
- Related researchers: Karl J. Friston, Jakob Hohwy, Giovanni Pezzulo, Anil K. Seth
The formalist of the Friston group’s active-inference programme — the person who worked out, in bookkeeping detail, how the discrete-state (active-inference) generative model updates its beliefs and how that update maps onto neuronal message passing. Where Friston states the principle and Seth carries it into the body, Parr supplies the machine.
Why he enters an interoception wiki
He does not work on interoception. He enters through Parr et al. (2019), a visual paper, because it isolates two claims the interoceptive account depends on but rarely gets to see undisplaced:
- Attention is covert action, and covert action is precision-setting. Parr’s formalism makes “attention” a policy selected to minimise expected free energy — the same object as the precision-weighting the wiki invokes on Predictive coding and Interoceptive precision. It is the formal identity behind Farb’s finding that attention decides which cortex represents an interoceptive signal.
- Individual differences live in precision. Fixed input plus different precisions yields different perceptual phenotypes — the exteroceptive statement of the aberrant-precision story the wiki runs for interoceptive psychopathology.
His textbook with Pezzulo and Friston (Active Inference, 2022) is the standard reference for the formalism the wiki meets secondhand through Seth & Friston and Petzschner et al. Thin page: one paper in raw/.