Memory Biases

Cryptomnesia

Definition

Cryptomnesia is when a forgotten memory resurfaces but feels like a new, original thought. We 'invent' something we've previously heard, read, or seen – without realizing the source is external.

Real-world example

In 1976 George Harrison was found liable for 'subconscious plagiarism' of the Chiffons' 'He's So Fine' in his own song 'My Sweet Lord.' The court accepted that he hadn't stolen deliberately – the melody was recognizable from a memory he'd forgotten he had.

Brown and Murphy (1989) demonstrated the phenomenon experimentally: participants who first generated ideas in a group later 'came up with' others' contributions as their own, with high confidence that it was their own invention.

Supplementary perspective

Cryptomnesia is a 'source monitoring error': the brain retrieves the content of the memory but loses the tag for where it came from. The phenomenon is common in creative work – ideas circulate, are forgotten, and resurface as 'new' – and an argument for logging ideas and their sources along the way.

Practical advice

Recognize

—Notice if a 'new' idea arrives unusually fully-formed – it may be a retrieved memory.
—Check whether the idea suspiciously resembles something you recently read or heard.
—Be extra careful right after deep research or reading in the field.

Counteract

—Keep notes with source references when collecting inspiration.
—Search for your 'new' idea before publishing – it may already exist.
—Discuss the idea with someone who knows the field before claiming originality.

Ethical use

—In creative work: credit sources you remember, and update credits when you discover forgotten influences.
—In academia: use plagiarism tools to catch unintentional reuse.
—In teams: normalize saying 'maybe I've heard this somewhere' – it doesn't weaken the idea.