What Does “Signalling” Mean?

I still feel a strong em­pa­thy for the post You Can’t Sig­nal to Rubes, which called out LessWrong for us­ing the word “sig­nal­ling” in­cor­rectly. That post got heav­ily, and rightly, down­voted be­cause it also got the defi­ni­tion wrong. :( But it had a point!

At the time of writ­ing, the cur­rent defi­ni­tion of sig­nal­ling on the LessWrong tag is:

Sig­nal­ing is be­hav­ior whose main pur­pose is to demon­strate to oth­ers that you pos­sess some de­sir­able trait. For ex­am­ple, a bird perform­ing an im­pres­sive mat­ing dis­play sig­nals that it is healthy and has good genes.

I’m not even sure I should cor­rect it, be­cause this does seem to sum­ma­rize the LessWrong con­sen­sus on what sig­nal­ling means. But we already have a term for sig­nal­ling de­sir­able prop­er­ties about your­self: virtue sig­nal­ling! Maybe you’ll ob­ject that “virtue sig­nal­ling” doesn’t have quite the right con­no­ta­tions. Ok. But, could you find an­other word? I would pre­fer for “sig­nal­ling” to point to the sub­ject of sig­nal­ling the­ory, which I un­der­stand to be the game the­ory of com­mu­ni­ca­tion (of­ten fo­cus­ing on evolu­tion­ary game the­ory).

Scott Alexan­der’s What Is Sig­nal­ing, Really? seems to get most things right:

In con­clu­sion, a sig­nal is a method of con­vey­ing in­for­ma­tion among not-nec­es­sar­ily-trust­wor­thy par­ties by perform­ing an ac­tion which is more likely or less costly if the in­for­ma­tion is true than if it is not true. Be­cause sig­nals are of­ten costly, they can some­times lead to a de­press­ing waste of re­sources, but in other cases they may be the only way to be­liev­ably con­vey im­por­tant in­for­ma­tion.

Although all of his ex­am­ples are about sig­nal­ling self-prop­er­ties, he never stipu­lates that, in­stead always us­ing the more gen­eral con­vey­ing-in­for­ma­tion defi­ni­tion. He also avoids the sig­nal­ling is au­to­mat­i­cally bad pit­fall. In­stead, he ex­plains that sig­nal­ling is of­ten un­for­tu­nately costly, but is nonethe­less a very use­ful tool.

How­ever, read­ing it, I’m not sure whether he means to con­trast sig­nal­ling with “mere as­ser­tion”, or whether he con­sid­ers as­ser­tion to be a kind of sig­nal­ling:

Life fre­quently throws us into situ­a­tions where we want to con­vince other peo­ple of some­thing. If we are em­ploy­ees, we want to con­vince bosses we are skil­lful, hon­est, and hard-work­ing. If we run the com­pany, we want to con­vince cus­tomers we have su­pe­rior prod­ucts. If we are on the dat­ing scene, we want to show po­ten­tial mates that we are charm­ing, funny, wealthy, in­ter­est­ing, you name it.

In some of these cases, mere as­ser­tion goes a long way.

[...]

In other cases, mere as­ser­tion doesn’t work.

[...]

I’ll char­i­ta­bly as­sume that he meant both cases to be types of sig­nal­ling. But for any­one who was mis­lead by the word­ing: sig­nal­ling is the the­ory of con­vey­ing in­for­ma­tion! Mere as­ser­tions, if they carry in­for­ma­tion, count as sig­nal­ling!

So, to sum­ma­rize the points I’ve raised so far:

  1. Some­times peo­ple talk like sig­nal­ling is just the bad thing (the dishon­est or not-max­i­mally-hon­est prac­tice of mak­ing your­self look good).

  2. Re­lat­edly, peo­ple tend to ex­clude “mere as­ser­tion” from sig­nal­ling, mak­ing sig­nal­ing and literal use of lan­guage mu­tu­ally ex­clu­sive.

  3. Often peo­ple re­strict sig­nal­ling to sig­nal­ling facts about your­self. (In fact, of­ten re­stricted to sta­tus sig­nal­ling.)

To be hon­est, I’m not even sure aca­demic uses of the term “sig­nal­ling” avoid the “mis­takes” I’m point­ing at! The Wikipe­dia ar­ti­cle Sig­nal­ling (eco­nomics) cur­rently be­gins with the fol­low­ing:

In con­tract the­ory, sig­nal­ling (or sig­nal­ing; see spel­ling differ­ences) is the idea that one party (termed the agent) cred­ibly con­veys some in­for­ma­tion about it­self to an­other party (the prin­ci­pal).

[Note that I’ve de­faulted to the Wikipe­dia spel­ling of sig­nal­ling; spel­ling on LessWrong seems mixed.]

On the other hand, the page on Sig­nal­ling The­ory (a page which is very biol­ogy-fo­cused, de­spite the broader ap­pli­ca­bil­ity of the the­ory) in­cludes ex­am­ples such as alarm calls (eg, birds warn­ing each other that there is a snake in the grass). Th­ese sig­nals can­not be in­ter­preted as facts about the sig­naller.

Per­haps it is a quirk of eco­nomics which re­stricts the term “sig­nal­ling” to hid­den in­for­ma­tion about the agent, and LessWrong in­her­ited this re­stricted sense via Robin Han­son?