Memory › Hyperamnesia

Flashback

A flashback is a sudden, intrusive memory that brings with it the cognitive and emotional experience of a traumatic event as though it were happening again, rather than simply being recalled. It can lead the person to act or feel, at least briefly, as though the original event is recurring in the present moment. A related but distinct pattern occurs after hallucinogenic drug use, involving the sudden return of perceptual distortions once the drug's short-term effects have worn off.

This has traditionally been recognised as one of the characteristic features of post-traumatic stress disorder, though it is also seen in substance misuse and other emotionally significant events, and the term is sometimes used loosely and inaccurately in everyday speech to describe ordinary intrusive recollections, which lack a flashback's distinctive re-experienced, emotionally immediate quality.

Also known as

Hallucinogen-related flashback

A distinct pattern occurring after the short-term effects of a hallucinogenic drug (or, less certainly, cannabis) have worn off, involving visual distortions, perceived movement at the edges of vision, flashes of colour, trailing images from moving objects, afterimages, and haloes, alongside more classical hallucinations.

Recognition features

• A sudden, intrusive memory bringing with it the cognitive and emotional quality of the original event, rather than a straightforward act of voluntary recall
• May lead to acting or feeling, at least momentarily, as though the traumatic event is happening again in the present
• Distinct from an ordinary intrusive recollection by this vivid, re-experienced, emotionally immediate quality
• The hallucinogen-related form involves a specific cluster of visual phenomena — trailing images, haloes, colour flashes, and perceptual distortion — occurring well after the drug's short-term effects have ended

Eliciting it at interview

• Ask specifically about sudden, unbidden re-experiencing of a distressing event, including whether it feels as though the event is happening again rather than simply being remembered
• Distinguish carefully from ordinary distressing memories by asking about the degree of emotional and sensory immediacy, and whether the person's behaviour is affected in the moment
• Where a hallucinogen-related pattern is suspected, ask specifically about visual disturbances such as trailing images, haloes, or colour flashes occurring after drug effects have otherwise worn off

Distinguishing features

• Differs from an ordinary intrusive recollection in its vivid, re-experienced emotional and sensory immediacy, rather than simply an unwelcome memory coming to mind
• Differs from flashbulb memory in being sudden, intrusive, and often distressing, rather than a stable, richly detailed memory recalled with confidence
• The hallucinogen-related form is distinguished by its specific visual character and its occurrence well after the drug's acute effects have ended

Common misconceptions

• That the term 'flashback' applies to any unwanted memory; it specifically describes a vivid re-experiencing with emotional and sensory immediacy, and is often used inaccurately to describe milder intrusive recollections
• That flashbacks only occur in post-traumatic stress disorder; they are also associated with substance misuse and other significant emotional events

Related phenomena

Hyperamnesia · Flashbulb Memory · Visual Hallucination · Eidetic Imagery

Diagnostically relevant to

Posttraumatic Stress Disorder (PTSD) (links open the DSM-5 Learning Lab)

Practice this

A war veteran describes sudden, unbidden moments where he is abruptly plunged back into the sights and sounds of combat, feeling for those moments as though it is happening again right now, complete with the original fear and physical tension. What is this? · A woman says that whenever she wants to, she can recall the moment she heard about a major national tragedy in extraordinary, stable detail — exactly where she was standing, what she was wearing, who she was with — and she is highly confident in the accuracy of every detail, though the memory has never once intruded on her unbidden. Before revealing the answer: is this a flashback? · A patient describes an unusually vivid memory of a significant past event. Before revealing the answer, decide what distinguishes a flashback from a flashbulb memory. · You are assessing a patient with a history of significant trauma and want to establish whether they experience flashbacks. Before revealing the answer, decide what you would ask. · Explain why a flashback is described as bringing back the cognitive and emotional quality of the original event, and why this matters for how it is distinguished from an ordinary unwanted memory.

Illustration

Walking past a car with its hazard lights flashing, a 30-year-old man involved in a serious accident the previous year is suddenly overwhelmed by the exact sounds, sensations, and fear of the crash itself, briefly ducking for cover before realising, moments later, that he is safely on a quiet pavement and nothing is actually happening.

References

• Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 5, 'Disorders of Memory'.