TL;DR: “Infohazard” means any kind of information that could be harmful in some fashion. Let’s use “cognitohazard” to describe information that could specifically harm the person who knows it.
Some people in my circle like to talk about the idea of information hazards or infohazards, which are dangerous information. This isn’t a fictional concept – Nick Bostrom characterizes a number of different types of infohazards in his 2011 paper that introduces the term (PDF available here). Lots of kinds of information can be dangerous or harmful in some fashion – detailed instructions for making a nuclear bomb. A signal or hint that a person is a member of a marginalized group. An extremist ideology. A spoiler for your favorite TV show. (Listen, an infohazard is a kind of hazard, not a measure of intensity. A papercut is still a kind of injury!)
I’ve been in places where “infohazard” is used in the Bostromian sense casually – to talk about, say, dual-use research of concern in the biological sciences, and describe the specific dangers that might come from publishing procedures of results.
I’ve also been in more esoteric conversations where people use the word “infohazard” to talk about a specific kind of Bostromian information hazard: information that may harm the person who knows it. This is a stranger concept, but there are still lots of apparent examples – a catchy earworm. “You just lost the game.” More seriously, an easy method of committing suicide for a suicidal person. A prototypical fictional example is the “basilisk” fractal from David Langford’s 1988 short story BLIT, which kills you if you see it.
This is a subset of the original definition because it is harmful information, but it’s expected to harm the person who knows it in particular. For instance, detailed schematics for a nuclear weapon aren’t really expected to bring harm to a potential weaponeer – the danger is that the weaponeer will use them to harm others. But fully internalizing the information that Amazon will deliver you a 5-pound bag of Swedish Fish whenever you want is specifically a danger to you. (…Me.)
This disparate use of terms is confusing. I think Bostrom and his intellectual kith get the broader definition of “infohazard”, since they coined the word and are actually using it professionally.*
I propose we call the second thing – information that harms the knower – a cognitohazard.
This term is shamelessly borrowed from the SCP Foundation, which uses it in a similar way in fiction. I figure the usage can’t make the concept sound any more weird and sci-fi than it already does.
(Cognitohazards don’t have to be hazardous to everybody. Someone who hates Swedish Fish is not going to spend all their money buying bags of Swedish Fish off of Amazon and diving into them like Scrooge McDuck. For someone who loves Swedish Fish – well, no comment. I’d call this “a potential cognitohazard” if you were to yell it into a crowd with unknown opinions on Swedish Fish.)
Anyways, hope that clears things up.
* For a published track record of this usage, see: an academic paper from Future of Humanity Institute and Center for Health Security staff, another piece by Bostrom, an opinion piece by esteemed synthetic biologist Kevin Esvelt, a piece on synthetic biology by FHI researcher Cassidy Nelson, a piece by Phil Torres.
(UPDATE: The version I initially published proposed the term “memetic hazard” rather than “cognitohazard.” LessWrong commentor MichaelA kindly pointed out that “memetic hazard” already meant a different concept that better suited that name. Since I had only just put out the post, I decided to quickly backpeddle and switch out the word for another one with similar provinence. I hate having to do this, but it sure beats not doing it. Thank you, MichaelA!)