Postdictive processing in perception

In postdictive processing, how a stimulus is perceived is influenced by processing of later stimulus input. Postdictive processing can occur on short time scales, up to ∼150 ms, and on time scales longer than 150 ms. This paper is concerned with postdiction on longer time scales. Evidence is reviewed for postdictive processing in long-range apparent motion, illusory saltation, and perceptual impressions of causality. It is also shown that some findings that have been interpreted as involving postdictive processing can be explained without recourse to postdiction. These include low contrast orientation discrimination, supposedly postdictive effects of colour change on choice, and volitional influence on ambiguous stimulus perception. It is proposed that postdictive interpretation may result from re-entrant processing operating on information held in a perceptual storage buffer, triggered by uncertainty or ambiguity in the stimulus information. Construction of events that occurred more than 150 ms before current perception implies that information about those events is retained in a memory store in order to avoid evident asynchronies in perception. It is proposed that that involves what is usually called iconic memory.