Evidence of Absence

July 1, 2008
Posted by Jay Livingston

Here’s a neat use of the Internet as a research tool.

Harrison Pope, a professor of psychiatry, had the idea that “repressed memory” was a fairly recent invention. Recent, not in the sense of the 1980s with those “recovered memories” that led to false convictions in child molestation cases. But recent in the larger historical sweep. Pope thought that the concept of “repressed memory” was something that arose with the romantic sensibility of the nineteenth century.

So now you have the hypothesis that repressed memory didn’t exist before 1800. But how can you prove nonexistence. Pope didn’t know of any references to it before then, and neither did anyone he talked to. But their knowledge of was certainly not comprehensive.

As Donald Rumsfeld said, absence of evidence is not evidence of absence.

So Pope offered a reward: $1000 to anyone who could come up with a reference to repressed memory before 1800. He posted it to some thirty Internet sites in three languages.


The strategy resembled that of distributed computing projects, like folding@home, where hundreds of personal computers are hooked up to form a network that functions like a supercomputer. But in this case, what was being networked was not computing power but good old-fashioned human brainpower and knowledge.

Pope got several responses, but none of them met the criteria. So he published his paper arguing that repressed memory was a nineteenth-century invention and therefore less a matter of neurology than of culture.*


*After Pope published the paper, someone did send a valid example – a French opera of 1786. Only one example, and even then, Pope had missed by only 14 years. A slightly longer write-up of the project can be found here.