1 Attention ‘capture ’ by the flash-lag flash

2 Eight participants made alignment judgements between a moving object and a stationary, continuously visible ‘landmark’. A reversing object had to overshoot the landmark by a significant amount in order to appear to reverse aligned with it. In addition, an adjacent flash irrelevant to the judgment task reliably increased this illusory ‘foreshortening’. This and other results are most simply explained by a model in which the flash causes attentional capture, complemented by processes of temporal integration and object representation. A flash used to probe the perception of a moving object’s position disrupts that perception, reminiscent of the Uncertainty Principle in quantum mechanics. 3 1