Neuronal latencies and the position of moving objects

Abstract

Neuronal latencies delay the registration of the visual signal from a moving object. By the time the visual input reaches brain structures that encode its position, the object has already moved on. Do we perceive the position of a moving object with a delay because of neuronal latencies? Or is there a brain mechanism that compensates for latencies such that we perceive the true position of a moving object in real time? This question has been intensely debated in the context of the flash-lag illusion: a moving object and an object flashed in alignment with it appear to occupy different positions. The moving object is seen ahead of the flash. Does this show that the visual system extrapolates the position of moving objects into the future to compensate for neuronal latencies? Alternative accounts propose that it simply shows that moving and flashed objects are processed with different delays, or that it reflects temporal integration in brain areas that encode position and motion. The flash-lag illusion and the hypotheses put forward to explain it lead to interesting questions about the encoding of position in the brain. Where is the 'where' pathway and how does it work?