B

Determining the psychophysical function that describes the flash-lag effect. A) Observers view a projection screen and remotely reposition a flash generated by an LED until it is seen as being aligned with the center of the moving bar (see <a href="#Fig2">Figure 2</a>). By measuring the discrepancy between the position of the perceived alignment and the physical position of the flash, the amount of lag seen over a wide range of image speeds can be determined. B) The psychophysical function that describes the flash-lag effect over a range of image speeds. The curve is a logarithmic fit to the lag reported by observers in the testing paradigm shown in (A). Bars are ±1 s.e.m. (After Wojtach et al., 2008)