Motion-induced positional biases in the flash-lag configuration

Zhuanghua Shi, Claudio de'Sperati

Research output: Contribution to journalArticlepeer-review


When both stationary and moving objects are present in the visual field, localizing objects in space may become difficult, as shown by illusory phenomena such as the Frohlich effect and the flash-lag effect. Despite the efforts to decipher how motion and position information are combined to form a coherent visual representation, a unitary picture is still lacking. In the flash-lag effect, a flash presented in alignment with a moving stimulus is perceived to lag behind it. We investigated whether this relative spatial localization (i.e., judging the position of the flash relative to that of the moving stimulus) is the result of a linear combination of two absolute localization mechanisms-that is, the coding of the flash position in space and the coding of the position of the moving stimulus in space. In three experiments we showed that (a) the flash is perceived to be shifted in the direction of motion; (b) the moving stimulus is perceived to be ahead of its physical position, the forward shift being larger than that of the flash; (c) the linear combination of these two shifts is quantitatively equivalent to the flash-lag effect, which was measured independently. The results are discussed in relation to perceptual and motor localization mechanisms.

Original languageEnglish
Pages (from-to)1027-1038
Number of pages12
JournalCognitive Neuropsychology
Issue number7-8
Publication statusPublished - 2008


  • Action perception
  • Flash-lag
  • Localization
  • Motion-position interaction
  • Visual illusion

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Experimental and Cognitive Psychology
  • Neuropsychology and Physiological Psychology


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