On the limits of evidence accumulation of the preconscious percept.

When a stimulus is repeated the memory representation for that stimulus is strengthened and performance in memory tests increases. To what extent this effect requires that each exposure elicits a fully-fledged conscious percept? In two Rapid Serial Visual Presentation (RSVP) experiments we explored whether the memory representations for words would accumulate evidence trough repeated exposure when none of those presentations induced a conscious percept. Participants were instructed to identify repeated items inserted in different RSVP streams and we isolated the first instance that an item was consciously perceived as repeating. The results showed that the probability of detecting a repetition for the first time was constant across repetitions. This effect signals a limit to the evidence accumulation process through repeated exposure. We discuss whether conscious perception modulates the decay of memory representations with below-threshold items resulting in extremely fleeting memory representations.