Repetition blindness: type recognition without token individuation.

Three experiments are described which use RSVP (rapid serial visual presentation) to demonstrate a new cognitive phenomenon called “repetition blindness”. Subjects have difficulty detecting repeated words-even when the two occurrences are nonconsecutive and differ in case (Experiment 1). In immediate verbatim recall of sentences (Experiment 2), subjects selectively omitted second instances of repeated words, sacrificing the meaning and grammaticality of the sentence. In Experiment 3, recognition threshold for the last word in a list was lowered, not elevated, when that word had also occurred earlier in the same list. Thus, repetition blindness does not result from a refractory period for recognition of second occurrences. These findings support a distinction between the perceptual processes of (i) recognizing a word as’being of a certain type, and (ii) individuating a word as a particular token of that type: repetition blindness occurs when words are recognized as types but not individuated as tokens.