Omitting details from post-event information: are true and false memory affected in the same way?

Participants who witness an event and later receive post-event information that omits a critical scene are less likely to recall and to recognise that scene than are participants who receive no post-event information (Wright, Loftus, & Hall, 2001). The present study used the Deese-Roediger-McDermott (DRM) paradigm, in which participants study lists of semantic associates (e.g., hot, snow, warm, winter) that commonly elicit false memories of critical non-presented words (e.g., cold), to determine whether omitting information from a second presentation decreases memory for both presented and non-presented information. Participants were presented with a list of the semantic associates of six non-presented words. For half the participants, this list was presented a second time with the semantic associates of one of the non-presented words omitted. As expected, participants were less likely to recall and to recognise the presented words when they had been omitted from the second presentation. Omission also decreased the rate at which non-presented words were recalled, although false recognition of these words was not reduced. These results suggest that false recognition may be particularly difficult to attenuate and that post-event omission may be more detrimental to memory accuracy than previously thought.