Dual representation theory (DRT) is a psychological theory of post-traumatic stress disorder (PTSD) first developed by Chris Brewin, Tim Dalgleish, and Stephen Joseph in 1996. In PTSD a hallmark symptom is the traumatic flashback, in which the person relives specific moments of the traumatic event as though they were happening in the present. This reliving in the present varies from a brief sense of the event occurring again to total absorption in the memory to the exclusion of the current environment (rare). Flashbacks are also not under voluntary control but are triggered by internal or external reminders of the event. They are vivid, emotionally intense, and may involve sensations such as cold and pain that were present during the event. The theory was based on the observation that flashbacks appeared to involve a kind of memory that had not been described by experimental psychologists – the “implicit” memories studied in the laboratory were also involuntary but differed in the person being unaware of them.

DRT proposed the existence of two separate memory systems that run in parallel during memory formation: the verbally accessible memory system (VAM) and situationally accessible memory system (SAM). The VAM system corresponds to ordinary autobiographical memory and contains information that was consciously processed and thus can be voluntarily recalled or described. DRT proposed that the VAM system is impaired during a traumatic event because of the high levels of arousal, creating gaps and discontinuities. What is encoded in the VAM system is the basis for people’s subsequent verbal accounts of the event and their attempts to understand and explain it. In contrast, the SAM system is unaffected by arousal and contains sensory and emotional information that was apprehended too briefly to be consciously encoded. This system is thought to be responsible for the presence of flashbacks and nightmares. A subsequent article Brewin, Chris R. (2001). “A cognitive neuroscience account of posttraumatic stress disorder and its treatment.” Behaviour Research and Therapy. 39 (4): 373-393. doi: 10.1016/s0005-7967(00)00087-5. ISSN 0005-7967. PMID: 11280338. proposed that the VAM system is supported by the hippocampus with the SAM system representing a form of non-hippocampally-based memory.

Background Prior to the development of DRT, existing psychological theories of PTSD fell into two camps: social-cognitive theories and information-processing theories. Social-cognitive theories (e.g. Horowitz's stress-response theory and Janoff-Bulman's shattered assumptions theory Janoff-Bulman, Ronnie. (1992). Shattered assumptions: towards a new psychology of trauma. New York: Free Press. ISBN 978-0743236256.) focused on the affected individual's assumptions about the world and the emotional and cognitive impact of the trauma on these assumptions. Information-processing theories (e.g. Foa's emotional processing theory ) focused more on attentional biases to threat-related stimuli and how representation and processing of this information may generate intrusive re-experiencing symptoms of PTSD. Brewin and colleagues noted that each of the two theory camps focused on characteristics of PTSD that were distinct and may be explained by different underlying processes. In devising DRT they drew from the work of several previous memory theorists. For example, Johnson and Multhaup Johnson, Marcia K.; Multhaup, Kristi S. (1992). “Emotion and MEM.” In S.-A. Christianson (Ed.), Handbook of emotion and memory (pp. 33-66). Hillsdale, N.J.: Erlbaum. ISBN 978-0805807042. had proposed multiple memory representations of everyday experiences. Jacobs and Nadel Jacobs, W. Jake; Nadel, Lynn. (1985). “Stress-induced recovery of fears and phobias.” Psychological Review. 92 (4): 512-531. doi: 10.1037/0033-295X.92.4.512. ISSN 0033-295X. PMID: 3903814. had argued that the acute effects of stress include a reduction in conscious memory processing and an enhancement to automatic, perceptual processing.

Major Theory Revisions Based on an independent neural model of spatial memory and imagery Byrne, Patrick; Becker, Suzanna; Burgess, Neil. (2007). “Remembering the past and imagining the future: A neural model of spatial memory and imagery.” Psychological Review. 114 (2): 340-375. doi: 10.1037/0033-295X.114.2.340. ISSN 0033-295X. PMID: 17500630. the theory was revised in 2010.Brewin, Chris R.; Gregory, James D.; Lipton, Michelle; Burgess, Neil. (2010). “Intrusive images and memories in psychological disorders: Characteristics, neural basis, and treatment implications.” Psychological Review. 117 (1): 210-232. doi: 10.1037/a0018113. ISSN 0033-295X. PMID: 20063969. It incorporated observations of the qualities of the two visual streams which correspond well to descriptions of VAMs and SAMs. Representations based on the ventral visual stream are contextualised within a spatiotemporal and autobiographical setting and are capable of mental manipulation (allocentric). In the R-DRT VAMs are now termed contextualized representations (C-reps). Representations based on the dorsal visual stream are less flexible, based on an egocentric perspective, and incorporate strong sensory, affective, and interoceptive elements. In the R-DRT SAMs are termed sensation-based representations (S-reps). The theory proposes that whereas C-reps and S-reps of an event are normally closely associated, this association can be weakened by the extreme levels of fear or horror produced by a traumatic event. Flashbacks correspond to the retrieval of an S-rep without the context provided by the corresponding C-rep. Therapy serves to overcome the usual avoidance of distressing moments, creating stronger C-reps with stronger connections to the S-reps and returning the memory system to its usual mode of operation.

The Memory and Identity theory of ICD-11 Complex PTSD was published in 2023.Hyland, Philip; Shevlin, Mark; Brewin, Chris R. (2023). “The Memory and Identity Theory of ICD-11 complex posttraumatic stress disorder.” Psychological Review. 130 (4): 1044–1065. doi: 10.1037/rev0000418. ISSN 0033-295X. PMID: 37338431. In ICD-11 the diagnosis of Complex PTSD requires that, after exposure to an extremely threatening or horrific event or series of events, a person meets the requirements for PTSD (evidence of re-experiencing the traumatic event in the here and now, avoidance, a perception of current threat, and impairment of functioning) as well as three additional severe and persistent features: 1) problems in affect regulation; 2) beliefs about oneself as diminished, defeated or worthless; and 3) difficulties in sustaining relationships and in feeling close to others. The theory attributes the symptoms of Complex PTSD both to disturbances in identity and to the disturbances in memory described by dual representation theory.

Empirical evidence

Support People with PTSD can readily distinguish the experience of flashbacks from other parts of the trauma memory. Flashbacks are associated with distinct characteristics and different physiological and neural responses,Brewin, Chris R. (2025). “Key concepts, methods, findings, and questions about traumatic memories.” Journal of Traumatic Stress. 38 (5): 771-80. doi: 10.1002/jts.23164. ISSN: 0894-9867. PMID: 40326850. supporting the argument they involve a different type of memory. As suggested by the theory, people with PTSD appear to have a more general difficulty in forming allocentric spatial memories Gilbertson, Mark W.; Williston, Stephanie K.; Paulus, Lynn A. et al. (2007). “Configural cue performance in identical twins discordant for posttraumatic stress disorder: Theoretical implications for the role of hippocampal function.” Biological Psychiatry. 62 (5): 513–520. doi:10.1016/j.biopsych.2006.12.023. ISSN 1873-2402. PMID: 17509537.Smith, Kirsten V.; Burgess, Neil; Brewin, Chris R.; King, John A. (2015). “Impaired allocentric spatial processing in posttraumatic stress disorder.” Neurobiology of Learning and Memory. 119, 69-76. doi: 10.1016/j.nlm.2015.01.007. ISSN 1095-9564. PMID: 25636201. and, the greater this difficulty, the more severe are their traumatic memory intrusions.Sierk, Anika; Manthey, Antje; King, John A. et al. (2019). “Allocentric spatial memory performance predicts intrusive memory severity in posttraumatic stress disorder.” Neurobiology of Learning and Memory. 166: 107093. doi: 10.1016/j.nlm.2019.107093. ISSN 1095-9564. PMID: 31536787.

Laboratory studies with healthy participants have also supported key aspects of the theory. In one group of studies participants were shown a trauma film, with a subset of them carrying out a visuospatial interference task such as Tetris. The standard finding is that such a task selectively reduces intrusive memories while leaving voluntary memory intact. This dissociation is more compatible with separate-trace theories such as DRT than with traditional accounts that involve only a single trace of the traumatic event.Brewin, Chris R. (2014). “Episodic memory, perceptual memory, and their interaction: Foundations for a theory of posttraumatic stress disorder.” Psychological Bulletin. 140 (10): 69-97. doi: 10.1037/a0033722. ISSN 0033-2909. PMID: 23914721.Lau-Zhu, Alex; Henson, Richard N.; Holmes, Emily A. (2019). “Intrusive memories and voluntary memory of a trauma film: Differential effects of a cognitive interference task after encoding.” Journal of Experimental Psychology: General. 148 (12): 2154-2180. doi: 10.1037/xge0000598. ISSN 0096-3445. PMID 31021150. Also supportive of the theory are findings that other interference tasks that do not actively engage visuospatial processing are much more inconsistent in their effects. Similar to the findings with samples of people with PTSD, individual differences predict how likely participants are to experience intrusions of the trauma film. Those with less good allocentric memory, and who are poorer at encoding contextual information, are more likely to experience subsequent intrusive memories of a traumatic film.Bisby, James A.; King, John A.; Brewin, Chris R.; Burgess, Neil; Curran, H. Valerie. (2010). “Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model.” Biological Psychiatry. 68 (3): 280-286. doi: 10.1016/j.biopsych.2010.01.010. ISSN 1873-2402. PMID: 20202625.Meyer, Thomas; Krans, Julie; van Ast, Vanessa; Smeets, Tom. (2017). “Visuospatial context learning and configuration learning is associated with analogue traumatic intrusions.” Journal of Behaviour Therapy and Experimental Psychiatry. 54 (Mar): 120-127. doi: 10.1016/j.jbtep.2016.07.010. ISSN 0005-7916. PMID 27467025.

Another group of studies has examined the effects of negative valence on memory for items versus contextual associations. Here, a single-trace theory would predict similar effects on memory for items and associations. A series of experiments showed that enhanced memory for negative items was accompanied by impaired memory for associations between items, including between pairs of negative items.Bisby, James A.; Burgess, Neil. (2014). “Negative affect impairs associative memory but not item memory.” Learning & Memory. 21 (1): 21-27. doi: 10.1101/lm.032409.113. ISSN 1072-0502. PMID: 24345636. The reduced associative memory but increased item memory for a traumatic item coincides with a shift towards greater amygdalar and less hippocampal activity.Bisby, James. A.; Horner, Aidan J.; Hørlyck, Lone D.; Burgess, Neil. (2016). Opposing effects of negative emotion on amygdalar and hippocampal memory for items and associations. Social Cognitive and Affective Neuroscience. 11 (6): 981-990. doi: 10.1093/scan/nsw028. ISSN 1749-5024. PMID: 26969864.  

Criticism