Understanding these cognitive processes illuminates factors that lead people to misidentify memories from one source as memories from another source. The core idea underlying the source monitoring approach is a simple one: in remembering, people name things that went unnamed during the event itself. Emotions play a role in recalling an event; activated memory records serve as input to ongoing cognitive processes; and remembering is a blend of reactivating, interpreting, retrieving, and constructing. People are sometimes aware of using inference to fill in missing details in their recollections, but more often these judgment processes are performed rapidly and without conscious reflection as an integral part of remembering. That is, remembering naturally and necessarily involves judgment and inference processes akin to those by which people perceive, understand, and label ongoing external events. Thus, not only is external reality transformed and interpreted as part of ongoing experiences but also remembering the past requires an additional layer of transformation and interpretation. Both controlled studies and anecdotal accounts suggest that the inability to remember sources is a common memory failure and that source confusion occurs in daily life. The authors discuss memory source monitoring, source monitoring and eyewitness suggestibility, memory impairment, bystander misidentification in lineups, verbal and nonverbal overshadowing in lineup identification, age-related developments in source monitoring, and source attribution and the construction of subjective experience. 47 references and 1 note