Abstract
Memory distortion reflects failures to identify the sources of mental experience (reality monitoring failures or source misattributions). For example, people sometimes confuse what they inferred or imagined and what actually happened, what they saw and what was suggested to them, one person's actions and another's what they heard and what they previously knew, and fiction and fact. Source confusions arise because activated information is incomplete or ambiguous and the evaluative processes responsible for attributing information to sources are imperfect. Both accurate and inaccurate source attributions result from heuristic processes and more reflectively complex processes that evaluate a mental experience for various qualities such as amount and type of perceptual, contextual, affective, semantic and cognitive detail, that retrieve additional supporting or disconfirming evidence, and that evaluate plausibility and consistency given general knowledge, schemes, biases and goals. Experimental and clinical evidence regarding cognitive mechanisms and underlying brain structures of source monitoring are discussed.