Why does the flash-lag effect occur?

There are neural delays on the order of 0.1 seg between light stimulating a location on the retina and the response of cortical neurons tuned to the corresponding location. Does this mean that we perceive a moving object in a lagging position respect to the real position?

It is suggested that this is not the case. It has been proposed brain mechanisms that compensate neural delays by extrapolating the position of the moving so that it is perceived in its 'real' position.

The flash, however, because of its unpredictability cannot be compensated. So, it is perceived delayed and this would be the cause of the flash-lag effect.

The flash-lag is not low level

Some neurophysiological studies point out that the sensory compensation could take place in very early stages of visual processing (e.g. the retina). Our study using a global form detection task suggests that this is not possible (Linares & López-Moliner, 2007).

The flash is not a neutral spatio-temporal marker

The most of explanations of the illusion assume that the flash presentation does not distort the perceived position of the moving object, but we showed that this interaction does actually happen (Experiment 1 and 2 in Linares, López-Moliner & Johnston, 2007).

Motion signal influences perceived position

When the internal texture of a stationary envelope drifts, the whole envelope is perceived as shifted in the direction of motion. Although this illusion demonstrates motion extrapolation, our experiments suggest that it might involve different mechanisms that the flash-lag effect (Linares & Holcombe, in press). We demonstrated, however, using the motion after-effect that motion signal influences perceived position (Experiment 3 in Linares, López-Moliner & Johnston, 2007).