The law of large numbers
Millions of people dream every night, so some dreams will match later events by chance alone.
Tested, replication failed
Precognition
Precognition is the claimed ability of knowing an event before it occurs. Status: tested, replication failed.
The other claimed abilities put to the same test: medium, clairvoyance, telepathy, clairsentience, clairaudience, psychometry, empathy, astral projection, healing and aura reading.
What people describe
Precognition is described as knowing about an event before it happens — most often through a dream, a sudden feeling of dread, or a clear image that later seems to match something real. People commonly report these experiences around accidents, deaths and disasters.
How it entered the record
The aeronautical engineer J. W. Dunne's 1927 book "An Experiment with Time" encouraged readers to record their dreams and look for later matches, and it was widely read. In 2011 Daryl Bem's "Feeling the Future" reported precognition effects in a leading psychology journal; attempts to replicate them, including a set published in 2012, did not reproduce the effect, and the paper became a central example in psychology's replication crisis.
The experiment
Daryl Bem, "Feeling the Future", Journal of Personality and Social Psychology, 2011
Read the paper: Bem (2011), “Feeling the future”, Journal of Personality and Social Psychology 100
How it was run
Nine experiments that ran standard psychology tasks backwards — for instance, students were tested on a word list and only afterwards told which words to rehearse.
Sample
Over 1,000 participants across nine studies
Result
Eight of nine reported effects at p < .01. Ritchie, Wiseman and French then ran three direct replications in 2012 and found nothing; journals initially declined to publish the null results.
This episode did more for psychology than for parapsychology: it became a standard example in the replication crisis, and helped push the field toward pre-registration.
Claim
Knowing an event before it occurs
Word from
Latin prae "before" + cognitio "knowing"
Status
Tested, replication failed
Where the word comes from
In use since the 1880s in psychical research.
What psychology offers instead
Hindsight
Memories of a vague dream are reshaped to fit what later happened, making the match look sharper than it was.
Flexible analysis
Choosing which comparisons to report after seeing the data can make chance results look significant.
How to test it fairly yourself
Write down premonitions in full, with the date, before anything happens, and have someone else check them against events using rules decided in advance. Count every entry — the misses as well as the hits.