The parade of lights flashing on a theatre marquee provides an important lesson in how the brain creates the illusion of motion using predictive processing. Whilst we know the bulb remains stationary, the lighting and dimming of each in succession makes it appear as if light is moving across the marquee. Even when successive bulbs are separated by a large space, our brains fill in the missing data to create the illusion that the motion has occurred smoothly from one point to the next. Such ‘apparent motion’ induces an internal model of motion, during which sensory predictions of the illusory motion feed back to V1.
We have performed a series of experiments using an apparent motion illusion to test spatial, temporal and causal parameters of visual predictions, using brain imaging and behaviour. We have observed that Primary visual cortex activity along the apparent-motion trace reflects illusory perception, as a result of predictive feedback from motion area V5. See also TMS Over V5 Disrupts Motion Prediction, Transfer of predictive signals across saccades, Detection of visual events along the apparent motion trace in patients with paranoid schizophrenia, The timing of feedback to early visual cortex in the perception of long-range apparent motion, Deciding what to see: the role of intention and attention in the perception of apparent motion, A spatio-temporal interaction on the apparent motion trace, Apparent motion: event-related functional magnetic resonance imaging of perceptual switches and States, Special treatment of prediction errors in autism spectrum disorder.
Here we asked, how does predictive feedback processing dynamically update to new retinotopic locations with eye-movements? We used 3T fMRI and eye-tracking whilst presenting an apparent motion illusion. We observed attenuated BOLD responses to predicted stimuli at a post-saccadic location in V1. The finding that pre-saccadic predictions update their retinotopic location in time for post-saccadic input, validates dynamic predictive coding theories in V1.