I’m sympathetic to the view that many human behaviors are for signaling. However so far it doesn’t seem like a very tight theory. We have a motley pile of actions labeled as ‘maybe signaling’, connected to a diverse range of characteristics one might want to signal. We have a story for why each would make sense, and also why lots of behaviors that don’t exist would make sense. However I don’t know why we would use the signals we do in particular, or why we would particularly signal the characteristics that we do. When I predict whether a middle class Tahitian man would want to appear to his work colleagues as if he was widely traveled, and whether he would do this by showing them photographs, my answers are entirely based on my intuitive picture of humans and holidays and so on; I don’t see how to derive them from my theory of signaling. Here are two more niggling puzzles:

Why would we use message-specific costly signals for some messages, when we use explicit language + social retribution for so many others?

Much of the time when you speak to others, your values diverge from theirs at least a little. Often they would forward their own interests best by deceiving you, ignoring social costs and conscience. But even in situations where risks from their dishonesty are large, your usual mode of communication is probably spoken or written language.

This is still a kind of costly signaling, as long as if the person faces the right threats of social retribution. Which they usually do I think. If a person says to you that they have a swimming pool, or that they write for the Economist, or that your boyfriend said you should give his car keys to them, you will usually trust them. You are usually safe trusting such claims, because if someone made them dishonestly they could expect to be found out with some probability, and punished. In cases where this isn’t so – for instance if it is a stranger trying to borrow your boyfriend’s car – you will be much less trusting accordingly.

This mode of costly signaling seems very flexible – spoken language can represent any message you might want to send, and the same machinery of social sanctions can be used to guard many messages at once. And we do use this for a lot of our communication. So why do we use different one-off codes for some small class of messages? What sets that class apart?

The main obvious limitation of language + social sanctions is that it requires a threat of social retribution large enough to discourage lying. This might be hard to arrange, if for instance there are very large gains from lying, if lies are hard to find, or if the person who might lie doesn’t rely on good relationships with the people who might be offended by the lies. So maybe we use non-costly signaling in those cases?

In many of those cases we do use a kind of costly signal, yet a different variant again to the kind hypothesized to covertly pervade human interactions. This type of signal is the explicit credential. When a taxi-driver-to-be takes a driving test or has a background check, then displays his qualifications, this is a signaling display. Acquiring these documents is much cheaper for a person who can drive and has a clean background, and you (or the taxi company) know this and treat him differently if he makes these signals. I say this seems different from the social signaling we usually think of because it is explicitly intended as a signal, and everyone readily accepts that that is the goal, and is fine with it. Which almost brings me to the next puzzle. In conclusion, it’s not clear whether the signaling that we usually think of as such mostly occurs in situations where language and social sanctions are hard to use, but it is at least not the only thing used in such cases.

Why is signaling seen as bad? Why don’t we know about our own signaling?

It is often taken as given that signaling is bad. If a person comes to believe that a behavior they once partook in is for signaling, it is not unusual for them to give it up on those grounds alone, without even noticing the step of inference required between ‘is for signaling’ and ‘is bad’. A signaling theory is apparently a cynical theory.

This seems odd, as badness is not implied at all by the theoretical costly signaling model. There, signaling can be bad or good socially, depending on the costs of carrying it out. There are gains from assorting people well – it is better if the good people do the important jobs for instance – but no guarantee that the costs of the fight won’t overwhelm the gains.

Another related oddity is that people are supposed to be mostly unaware that they are signaling. Nobody bats an eyelid when a person claims to realize that they were doing a thing for signaling in the past. Talk of signaling is full of ‘Maybe I’m just doing this for signaling, but …’. Yet in the naive model of human psychology, it is at least a bit odd to be unaware of your motives in taking an action until months later. It’s true that people quite often don’t appear to have a good grasp of their own drives, yet in signaling this seems to be the normal expectation. And again, the theoretical model of costly signaling says nothing of this. It’s not obvious why you should expect this at all, given that model.

Another reason this seems strange is that we do have a lot of other explicit forms of signaling that we are aware of and ok with, as mentioned above (qualifying tests, ID cards, licenses). It is not that we have a problem with spending effort on almost-zero-sum games, or paying costs to look good.

An explanation

I’d like to suggest an explanation: costly signaling (of the message-specific unconscious variety) is largely used to communicate illicit messages. For instance, many messages about one’s own wealth, accomplishments, status, or sexual situation, and other messages about social maneuvering and judgement, seem to be illicit. Such things are also common targets of signaling theories, though my reasons for suggesting this explanation are mostly theoretical.

Illicit messages can’t be honestly transmitted using language and social norms, for a few reasons. Illicit things often shouldn’t be said explicitly, for plausible deniability, to avoid common knowledge, etc. This means you generally can’t use language to communicate illicit things, because language is explicit. This is one reason language + social retribution doesn’t work well for illicit messages. But also if you successfully have plausible deniability or prevent the message spreading far, both of these make social retribution hard to arrange. So implicit messages are quite hard to make honest through language + social retribution. Or through explicit verification for that matter, which is similar. Yet if such messages are to be listened to at all, they need some other guarantee, which other kinds of non-explicit costly signaling can provide. So this would explain the first puzzle.

If we had a set of signals just for illicit messages, it would be very silly to claim that we were aware of sending such things, and perhaps upsetting to believe that we were and to lie about it. So for the usual reasons that people are thought to be unaware of their less desirable tendencies, it wouldn’t be surprising if people were unaware of the signals they were sending. And if such signals were largely used for illicit messages, it would be unsurprising if we universally thought of signaling as an illicit activity. So this would explain the second puzzle.