False categorical memories: effects of list composition, divided attention & pre-retrieval warnings

Encoding lists of categorised words produces robust false memory for non-presented exemplars but few false memories for category labels. The present research examined the conditions under which categorical false memories can be elicited by variations in list composition in which a subset of category labels was presented for half of the lists. In Experiment 1, participants encoded lists of exemplars with or without the presence of category labels under full or divided attention conditions. Presentation of a subset of category labels produced false memories for non-presented labels and dividing attention reduced this effect. In Experiment 2, participants encoded lists as in Experiment 1 and prior to retrieval, were (or were not), given warnings about the nature of false memory effects and to avoid false memory errors. Categorical false memories arose when a subset of labels was encoded and warnings did not significantly reduce their magnitude, testifying to the robustness of this effect. Explanations are considered from the perspective of activation monitoring, fuzzy trace theory and how encoding and subsequent monitoring interact.