"I know what you did on the last trial"--a selective review of research on priming in visual search

One could argue that studies of how we scan our visual environment have been stuck in the eternal present, investigating the properties of a particular search situation without reference to what has occurred before. There is, however, increasing evidence that what we have previously viewed, perhaps only moments before, has a large influence on what we see, what grabs our attention and how we organize the visual scene. A large amount of evidence pertinent to the question of what has been termed priming in visual search is reviewed here, evidence from psychophysics, neurophysiology and neuropsychology. Two theoretical accounts of priming are contrasted, the view that priming reflects facilitation of the processing of specific features versus views that priming reflects facilitated object formation and subsequent response selection. Strong versions of either view are rejected as neither can explain all the available evidence on their own. It is concluded that priming in visual search is probably not a unitary phenomenon but can reflect processing changes at various levels of the hierarchy of perceptual processing.