Flash lag illusion

The first proposed explanation for the flash-lag effect is that the visual system is predictive, accounting for neural delays by extrapolating the trajectory of a moving stimulus into the future.

[5][6] The latency-difference proposal tacitly rests on the assumption that awareness (what the subject reports) is an on-line phenomenon, coming about as soon as a stimulus reaches its "perceptual end-point".

This postdictive framework is consistent with findings in other fields, such as backward masking in visual psychophysics (Bachmann, 1994), or the color phi phenomenon.

Thus, the corrected position of the moving target is calculated by combining the sensory flux with the internal representation of the trajectory, both of which exist in the form of probability distributions.

To manipulate the trajectory is to change the precision and therefore the relative weight of these two information when they are optimally combined in order to know where an object is at the present time.

The flash-lag effect. When a visual stimulus moves along a continuous trajectory, it may be seen ahead of its veridical position with respect to an unpredictable event such as a punctuate flash. This illusion tells us something important about the visual system: contrary to classical computers, neural activity travels at a relatively slow speed. It is largely accepted that the resulting delays cause this perceived spatial lag of the flash. Still, after several decades of debates, there is no consensus regarding the underlying mechanisms.
The still photo showing the green flash (frame 073, black background omitted).