Survival of the grouped, or three's a crowd? Repetition blindness in groups of letters and words

When stimuli are presented rapidly, repetitions are often undetected--a phenomenon called "repetition blindness" (RB; Kanwisher Cognition, 27, 117-143, 1987). Grouping of nonlinguistic items has been found to prevent RB (Goldfarb & Treisman Psychonomic Bulletin & Review, 18, 1042-1049, 2011). In order to determine whether this effect could be found with letters and words, participants viewed rapid serial visual presentation and brief simultaneous visual presentation streams containing groups of linguistic stimuli and provided judgments of frequency. The collection of reaction times and an explicit question about strategy use allowed for analyses of the participants' processing strategies. Two groups of participants emerged: one that demonstrated RB for groups of stimuli, and another that demonstrated enhanced perception with stimulus grouping. These participant groups did not appear to differ on the basis of explicit processing strategies or reaction times.