Berlyne (1972) defined confabulation as “...a falsification of memory occurring in clear consciousness in association with an organically derived amnesia.” He distinguished between:
Patients who have suffered brain damage or lesions, especially to the Prefrontal cortical regions, may have confabulation of memories as a symptom. Patients with Korsakoff's syndrome characteristically confabulate by guessing an answer or imagining an event and then mistaking their guess or imagination for an actual memory. In some cases, confabulation is a function of the brain's chemistry, a mapping of the activation of neurons to brain activity. Confabulation can also occur as a result of damage to the Anterior communicating artery (ACoA), in the Circle of Willis.
In the 1970s a number of researchers and theories started to emphasise what has been called the constructivist view of memory, maintaining that reasoning influences memory, in contrast to the prevailing view at the time which was that memory is essential for proper reasoning. Theorists such as Bransford and Franks noted the significance of personal beliefs and desires, or more technically scripts and schemas, in memory retrieval.
Constructivism has fallen out of fashion recently due to the contention that it is either false or un-testable. Memory is presumably not always reconstructive as the considerable evidence of its veridical quality is testament. Constructivism cannot simply be rephrased as the thesis that memory is not always reproductive. As Reyna and Lloyd point out, this amounts to the claim that memory is sometimes reproductive and sometimes reconstructive; which is unexplanatory and unfalsifiable as any result can be accommodated post hoc. Because of this a number of theories have now been advanced which instead focus on the mechanism by which an essentially accurate memory system can sometimes produce erroneous results. Notably, both source monitoring framework and fuzzy-trace theory purport to both indicate when false memories are likely to occur and give a more detailed explanatory account than either reproductive or constructivist views.
Source monitoring refers to the process by which we discriminate between internally and externally derived memory sources as well as differentiations within the external and external domains: differentiating between two external sources or between internal sources, for instance between what was said and what was thought. The theory postulates that these decisions are made based on the characteristics of memories compared to norms for memories for different sources, such as the proportions of perceptual, contextual, affective and semantic information featured in the encoding of the memory. Under the source monitoring framework false memory is seen as a failure to attribute information to the correct source. This happens when there is insufficient information available to discriminate between different sources (perhaps because of natural deterioration), or when the wrong criterion is used to discriminate. For example a doctor might mistakenly think a patient is on a specific medicine because they were discussing the medicine with a colleague shortly after seeing them.
Fuzzy trace theory is based on the assumption that memory is not stored in unitary form. Instead memories are encoded on a number of levels, from an exact ‘verbatim’ account, to ‘gist’ which represents the overall meaning of the event. False memory effects are usually (but not always) explained as a reliance on gist traces in a situation when verbatim traces are needed. Because of this people may mistakenly recall a memory that only goes along with a vague gist of what happened, rather than the exact course of events. Essentially there are three reasons why people might do this. There is thought to be a general bias towards the use of gist traces in cognition due to their resource efficiency and people will tend to use gist traces when it is thought that they will be adequate to satisfy the demands of the situation. Second, verbatim traces are said to be inherently less stable than gist and decay quicker. Finally, during the course of forgetting memories fragment and gist and verbatim can become independent.