Perceptual Multistability asMarkov Chain Monte Carlo Inference

…what?

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Outline

Construct rational model of visual process.• Algorithmic/computational model of mental

processing– Not about neurons– Bayesian inference promising, computationally infeasible

• Explain existing results– Multistability– Focus on binocular rivalry

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Your brain is flat out making stuff up

Sensory inputs fundamentally impoverished.• Reconstructing 3D world from 2D vision

Bayesian inference promising• Belief (posterior) computed from sensory inputs

(likelihood) and plausible world structures (prior)• Effective in practice• Requires approximation• Prior proposed approximation don’t represent

uncertainty

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Lying to your brain

Binocular rivalry arises from presenting inconsistent images to each eye.

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Lying to your brain

Binocular rivalry arises from presenting inconsistent images to each eye.

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Your brain is flat out making stuff up

Sensory inputs fundamentally impoverished.• Reconstructing 3D world from 2D vision

Bayesian inference promising• Belief (posterior) computed from sensory inputs

(likelihood) and plausible world structures (prior)• Effective in practice• Requires approximation• Prior proposed approximation don’t represent

uncertainty

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Your brain knows it’s making stuff up

Sensory inputs fundamentally impoverished.• Reconstructing 3D world from 2D vision

Bayesian inference promising• Belief (posterior) computed from sensory inputs

(likelihood) and plausible world structures (prior)• Effective in practice• Requires approximation• Prior proposed approximation don’t account for

multistability

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Outline

New model of approximation (MCMC)• Exploration of hypothesis space corresponds to

switches in multistability.• MCMC gives accurate predictions of state

distributions!

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Modelling the visual process

Modelling visual process as Bayesian inference:

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Modelling the visual process

Latent imageOutlier process

Retinal stimulus

Relationship among pixels:

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Accurately confused

Binocular rivalry:

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Accurately confused

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Accurately confused

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Accurately confused

Travelling waves:

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Accurately confused

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Summary

Rational model of visual process multistability• Simple model of visual process (Bayesian)• Standard approximation techniques from machine

learning (MCMC)• Accurately predicts experimental results, including

multistability in binocular rivalry• Provides high-level intuition of neurally-plausible

explanations.

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Math

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Math