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Research provides insight that can help assess whether witness testimony is accurate. Witness testimony may be inaccurate because a witness is lying, or because a witness has a false memory. Research in psychology can provide some insight into factors associated with accurate and inaccurate memory that might help inform testimony evaluations. However, data suggests that jurors may have problems distinguishing accurate and inaccurate testimony, and that assumptions jurors rely on may differ from those shown to be important by scientific research. Thus, we can pinpoint potential cases in which decision-makers in the legal system might be particularly likely to make mistakes when interpreting witness testimony.

The Difficulty Detecting Deception

Research highlights the difficulty of detecting deception in witness testimony, and cues to deceit have been described as “faint and unreliable”. Meta-analyses suggest that people are correct in identifying whether a statement is the truth or a lie about 54% of the time.

Charles Bond and Bella DePaulo, ‘Accuracy of deception judgments’ (2006) 10(3) Personality and Social Psychology Review 214.

Maria Hartwig and Charles Bond (2011), ‘Why do lie-catchers fail? A lens model meta-analysis of human lie judgments’ (2011) 137(4) Psychological Bulletin 643.

Techniques to Detect Deception

Pär Anders Granhag and Leif A. Strömwall , Detection Deception in Forensic Contexts (Cambridge University Press, 2009).

Specific techniques have included:

(1) Physiological measures such as polygraphs (according to which those who are lying have a heightened stress response).

(2) Measures of non-verbal behaviour. For example, Paul Ekman and Maureen O’Sullivan, ‘From flawed self-assessment to blatant whoopers: The utility of voluntary and involuntary behaviour in detecting deception’ (2006) 24 Behavioral Sciences and the Law 673, and

(3) Measures of words and descriptions used. For example, Matthew Newman, James Pennebaker, Diane Berry, and Jane Richards, ‘Lying words: Predicting deception from linguistic styles’ (2003) 29(5) Personality and Social Psychology Bulletin 665; Bruno Vershuere, Glynis Bogaard and Ewout Meijer, ‘Discriminating deceptive from truthful statements using the verifiability approach’ (2020) Applied Cognitive Psychology.

However, these cues are unlikely to be sufficiently reliable for use in legal procedures, in part because they are subtle and not always present.

Aldert Vrij and Jeannine Turgeon, ‘Evaluating credibility of witnesses – are we instructing jurors on invalid factors’ (2018) 11(2) Journal of Tort Law 231. 

Alicia Nortje and Colin Tredoux, ‘How good are we at detecting deception? A review of current techniques and theories’ (2019) 49(4) South African Journal of Psychology 491.

Techniques to Make Deception Clearer

In order to help people better distinguish truth and lies, researchers have developed techniques to increase relevant differences between those telling the truth and those lying. For example:

Aldert Vrija, Samantha Manna, Sharon Leala, and Ronald P. Fisher, ‘Combining Verbal Veracity Assessment Techniques to Distinguish Truth Tellers from Lie Tellers’ (2020) The European Journal of Psychology Applied to Legal Context.

Aldert Vrij, Samantha Mann, Ronald Fisher, Sharon Leal, Rebecca Milne, and Ray Bull, ‘Increasing cognitive load to facilitate lie detection: The benefit of recalling an event in reverse order’ (2008) 32(3) Law and Human Behavior 253.

Coral Dando and Ray Bull, ‘Maximising opportunities to detect verbal deception: Training police officers to interview tactically’ (2011) 8(2) Journal of Investigative Psychology and Offender Profiling 189. 

Children and Trauma

Special care should be taken when examining the testimony of people who have been subjected to trauma, particularly children. This special care is required because cues typically associated with lies may be predictably present even where the person giving testimony is telling the truth. For example, victims of trauma, particularly when young, might be susceptible to what is known as memory “blending” which can lead to inconsistencies in accounts.

Rebecca K. Helm, Caisa E. Royer and Stephen J. Ceci, ‘Forensic analysis of child interrogations and testimony’ in Michael Bowers and Wendy Koen (eds.), The Psychology and Sociology of Wrongful Convictions (Academic Press, 2018). 

Memory is not always accurate, and false memories can arise either spontaneously or as the result of suggestion.

Charles Brainerd and Valerie Reyna, The Science of False Memory (Oxford University Press, 2005). 

Elizabeth Loftus, ‘Make believe memories’ (2003) 58(11) American Psychologist 867.

Mark Howe and Lauren Knott, ‘The fallibility of memory in judicial processes: Lessons from the past and their modern consequences’ (2015) 23(5) Memory 633.

Mark Howe, Lauren Knott and Martin Conway, Memory and Miscarriages of Justice (Routledge, 2017). 

Spontaneous false memory

Spontaneous false memories are false memories that arise without external influence as a result of internal processes. For example, a false memory may arise where a person encodes the “gist” of an event, and later recalls this gist but imposes incorrect specific details on it as a result of forgetting true specific details. For example, research has shown that people who see a list of words relating to sleep are likely to later remember that they heard the word sleep even when they did not.

Henry Otgaar and Mark Howe, ‘When spontaneous statements should not be trusted: False memories in children and adults’ in Henry Otgaar and Mark Howe (Eds.), Finding the Truth in the Courtroom (Oxford University Press, 2018). 

Research shows that spontaneous false memory:

(1) Is more likely in adults than children.

Charles Brainerd, Valerie Reyna, and Stephen Ceci, ‘Developmental reversals in false memory: A review of data and theory’ (2008) 134(3) Psychological Bulletin 343.

Henry Otgaar, Mark Howe, Maarten Peters, Melanie Sauerland and Linsey Raymaekers, ‘Developmental trends trends in different types of spontaneous false memories: Implications for the legal field’ (2013) 31(5) Behavioral Sciences & the Law 666.

(2) Can arise as the result of source confusion (inappropriately connecting experiences). This confusion can lead to identifying a familiar but innocent person as the culprit of an offence, or to believing that an imagined event really happened.

David Ross, Dorothy Marsil, Tanja Benton, Rebecca Hoffman, Amye Warren, R. Lindsay and Richard Metzger, ‘Children’s susceptibility to misidentifying a familiar bystander from a lineup: Why younger is better’ (2006) 30(3) Law and Human Behaviour 249. 

David Ross, Stephen Ceci, David Dunning and Michael Toglia, ‘Unconscious transference and mistaken identity: When a witness misidentifies a familiar but innocent person’ (1994) 79(6) Journal of Applied Psychology 918. 

Stephen Ceci, Mary Huffmann, Elliott Smith, and Elizabeth Loftus, ‘Repeatedly thinking about a non-event: Source misattributions among preschoolers’ (1994) 3(3-4) Consciousness and Cognition 388.

(3) May be more likely in certain people or situations, for example as a result of individual differences, differences in experiences, or emotion.

Jason Watson, Michael Bunting, Bradley Poole, and Andrew Conway, ‘Individual differences in susceptibility to false memory in the Deese-Roediger-McDermott paradigm’ (2005) 31(1)  Journal of Experimental Psychology: Learning, Memory, and Cognition 76. 

Henry Otgaar, Mark L. Howe, and Peter Muris, ‘Maltreatment increases spontaneous false memories but decreases suggestion‐induced false memories in children’ (2017) 35(3) British Journal of Developmental Psychology 376.

Charles Brained, Lilian Stein, R. Silveira, Gustavo Rohenkohl and Valerie Reyna, ‘How does negative emotion cause false memories’ (2008) 19(9) Psychological Science 919.

The influence of suggestion

False memories can arise as the result of external suggestion, for example as a result of leading questions in interviews that suggest a particular answer to the person being interviewed.

Elizabeth Loftus ‘Planting misinformation in the human mind: A 30-year investigation of the malleability of memory’ (2005) 12(4) Learning & Memory 361.

Research shows that false memory arising from suggestion:

(1) Is generally, but not always, more likely in children than adults.

Maggie Bruck and Stephen Ceci. ‘The suggestibility of children’s memory’ (1999) 50(1) Annual review of psychology 419.

Henry Otgaar, Mark L. Howe, Nathalie Brackmann, and Daniël van Helvoort. ‘Eliminating age differences in children’s and adults’ suggestibility and memory conformity effects’ (2017) 53(5) Developmental Psychology 962.

(2) Can arise as a result of receiving misinformation or as a result of suggestive questioning (i.e. being asked leading questions).

Distinguishing true and false memory

Research has not yet identified a reliable way to distinguish true and false memory, although factors discussed above can help provide insight into whether a memory is likely to be true or false. For example, a memory is more likely to be false where a person has experienced suggestive questioning.

Researchers have attempted to find ways to distinguish true and false memory by analysing the memory itself. The criterion which has been found to best differentiate true from false statements is the level of detail reported. True memory reports tend to contain more detail, particularly sensory detail such as sight, sound, feel, taste, or smell, than false memories do.

Aldert Vrij, ‘Criteria-based content analysis: A qualitative review of the first 37 studies’ (2005) 11(1) Psychology, Public Policy, and Law 3. 

Jonathan Schooler, Delia Gerhard and Elizabeth Loftus, ‘Qualities of the unreal’ (1986) 12(2) Journal of Experimental Psychology: Learning, Memory, and Cognition 171.

However, research has also shown that some false memories (known as rich false memories) contain significant amounts of detail.

Kimberley Wade, Maryanne Garry and Kathy Pezdek, ‘Deconstructing rich false memories of committing crime: Commentary on Shaw and Porter’ (2017) 29(3) Psychological Science 471.

Importantly, research suggests that non-experts may rely on cues that have been shown not to be accurate when assessing whether a memory is likely to be true or false. For this reason, there is a risk that non-experts including jurors could make predictable mistakes when assessing testimony.

Tanja Benton, David Ross, Emily Bradshaw, W. Neil Thomas, and Gregory S. Bradshaw. ‘Eyewitness memory is still not common sense: Comparing jurors, judges and law enforcement to eyewitness experts’ (2006) 20(1) Applied Cognitive Psychology 115. 

Bradley McAuliff and Margaret Bull Kovera, ‘Estimating the effects of misleading information on witness accuracy: Can experts tell jurors something they don’t already know?” (2007) 21(7) Applied Cognitive Psychology  849.

For example, non-experts tend to have high levels of believe that ‘repressed memories’ are accurate when compared to experts, who are much more skeptical.

Lawrence Patihis, Lavina Ho, Ian Tingen, Scott Lilienfeld and Elizabeth Loftus, ‘Are the “memory wars” over? A scientist-practitioner gap in beliefs about repressed memory’ (2014) 25(2) Psychological Science 519. 

Similarly, non-experts tend to associate witness confidence with greater witness accuracy. Scientific research shows that while confidence generally predicts accuracy, this relationship can be seriously compromised under certain conditions.

Neil Brewer, and Anne Burke, ‘Effects of testimonial inconsistencies and eyewitness confidence on mock-juror judgments” (2002) 26(2) Law and Human Behavior 353.

Elizabeth Loftus and Rachel Greenspan, ‘If I’m certain, is it true? Accuracy and confidence in eyewitness memory’ (2017) 18(1) Psychological Science in the Public Interest 1.

Potential mistakes based on mistaken beliefs have the potential to lead to both wrongful convictions and systematic failures to successfully prosecute in cases where prosecution may be appropriate.