People sometimes try to determine whether they have actually experienced an event they have in mind, or whether this memory is based on imagination. The processes by which a person attributes a memory to an actual experience (external source) or imagination (internal source) is called reality monitoring (RM). Although the RM concept is not related to deception, scholars believe that the concept has this application and can be used as a lie detection tool. Much of the RM deception research is concerned with testing the assumption that RM assessments can be used to discriminate between liars and truth tellers.
The core of RM is that memories based on real experiences differ in quality from memories based on fiction. In their seminal work on memory characteristics, Marcia Johnson and Carol Raye argued that memories of real experiences are obtained through perceptual processes. They are therefore likely to contain sensory information: details of smell, taste, or touch, visual details, and details of sound; contextual information: spatial details (details about where the event took place and details about how objects and people were situated in relation to each other) and temporal details (details about the time order of events and the duration of events); and affective information: details about people’s feelings throughout the event. These memories are usually clear, sharp, and vivid. In contrast, memories about imagined events are derived from an internal source and are therefore likely to contain cognitive operations, such as thoughts and reasonings (“I must have had my coat on as it was very cold that night”). They are usually vaguer and less concrete.
From 1990 onward, scholars have examined whether RM analyses can be used to discriminate between truths and lies. The assumption those scholars make is that truths are recollections of experienced events, whereas lies are recollections of imagined events. Obviously not all lies are descriptions of events that a person did not experience. Many lies are not about events but are about people’s feelings, opinions, or attitudes. And even when people lie about events (about their actions and whereabouts), they can sometimes describe events that they actually have experienced. For example, a burglar who denies having committed a burglary last night can claim that he went to the gym instead. He then can describe an actual visit he had made to the gym (but on another occasion).
Researchers have examined whether deceptive statements that are based on events that the liar imagined differ in terms of RM criteria from truthful statements about experienced events. The typical procedure is that liars and truth tellers are interviewed, and these interviews are taped and transcribed.
RM experts check for the presence of RM criteria in these transcripts. To date, a standardized set of RM deception criteria has not been developed. Different researchers use different criteria and sometimes use different definitions for the same criterion.
Most researchers include the following criteria in their RM veracity assessment tool:
- Clarity and vividness of the statement: This criterion is present if the report is clear, sharp, and vivid instead of dim and vague.
- Perceptual information: This criterion refers to the presence of sensory information in a statement, such as sounds (“He really shouted at me”), smells (“It had a smell of rotten fish”), tastes (“The chips were very salty”), physical sensations (“It really hurt”), and visual details (“I saw the nurse entering the ward”).
- Spatial information: This criterion refers to information about locations (“It was in a park”) or the spatial arrangement of people and/or objects (“The man was sitting to the left of his wife”).
- Temporal information: This criterion refers to information about when the event happened (“It was early in the morning”) or explicitly describes a sequence of events (“When he heard all that noise, the visitor became nervous and left”)
- Cognitive operations: This criterion refers to descriptions of inferences made by the participant at the time of the event (“It appeared to me that she didn’t know the layout of the building”) or inferences/opinions made when describing the event (“She looked smart”).
All criteria are thought to be more present in truthful than in deceptive accounts, except the cognitive operations criterion, which is thought to be present more in deceptive than in truthful accounts. Research has shown general support for these assumptions, although the support for some criteria, such as temporal and spatial details, is stronger than the support for other criteria, such as cognitive operations. Moreover, truths and lies can be detected above the level of chance with the RM tool, with average truth and lies accuracy scores being just below 70%.
There are restrictions in using an RM veracity assessment tool. For example, the tool cannot be used with young children. In some circumstances, children do not differentiate between fact and fantasy as clearly as adults do, for several reasons, including the fact that children have a richer imagination than adults. Children may therefore be better than adults at imagining themselves performing acts. It is probably also difficult to use the RM tool when people talk about events that had happened a long time ago. Over time, cognitive operations may develop in memories of experienced events because they facilitate the remembering of events. Someone who drove fast in a foreign country may try to remember this by remembering the actual speed the speedometer indicated; alternatively, the person could remember this by logical reasoning and by deducing that he or she must have driven fast because he or she was driving on the motorway. Imagined memories, on the other hand, can become more vivid and concrete over time if people try to visualize what might have happened.
- DePaulo, B. M., Lindsay, J. L., Malone, B. E., Muhlenbruck, L., Charlton, K., & Cooper, H. (2003). Cues to deception. Psychological Bulletin, 129, 74-118.
- Johnson, M. K., & Raye, C. L. (1981). Reality monitoring. Psychological Review, 88, 67-85.
- Lindsay, D. S. (2002). Children’s source monitoring. In H. L. Westcott, G. M. Davies, & R. H. C. Bull (Eds.), Children’s testimony: A handbook of psychological research and forensicpractice (pp. 83-98). Chichester, UK: Wiley.
- Masip, J., Sporer, S., Garrido, E., & Herrero, C. (2005). The detection of deception with the reality monitoring approach: A review of the empirical evidence. Psychology, Crime, & Law, 11, 99-122.
- Vrij, A. (2000). Detecting lies and deceit: The psychology of lying and its implications for professional practice. Chichester, UK: Wiley.
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