Motivation for post: As a former CFAR instructor, longtime teacher, and rationality pundit, I find myself giving lots of advice in lots of different contexts.  I also try to check in from time to time to find out which bits of advice actually proved helpful to people.  Over the years, I've heard from a genuinely surprising number of people that my (offhand, very basic, not especially insightful) thoughts on "shoulder advisors" were quite useful to them, and remained useful over time.  So: a primer.

"There's a copy of me inside your head?" Hermione asked.

"Of course there is!" Harry said. The boy suddenly looked a bit more vulnerable. "You mean there isn't a copy of me living in your head?"

There was, she realized; and not only that, it talked in Harry's exact voice.

"It's rather unnerving now that I think about it," said Hermione. "I do have a copy of you living in my head. It's talking to me right now using your voice, arguing how this is perfectly normal."

"Good," Harry said seriously. "I mean, I don't see how people could be friends without that."

The term "shoulder advisor" comes from the cartoon trope of a character attempting to make a decision while a tiny angel whispers in one ear and a tiny devil whispers in the other.

Many people have multiple shoulder advisors.  Some, no doubt, carry a literal metaphorical angel and devil around with them.  Others may sometimes hear the whispers of some of their favorite beloved fictional characters.  It's quite common in my experience for people to have shoulder copies of their parents, or their best friends, or their romantic partners, or particularly impactful teachers or bosses or mentors.

This is not schizophrenia (though for all I know it may use some of the same hardware, or may be a low-key, non-pathological version of schizophrenia in the same way that a healthy self-preservation instinct could be thought of as a low-key, non-pathological version of a phobia or an anxiety disorder). 

Rather, there is simply some kind of subroutine in the brain of most humans that is capable of taking in training data and learning what a given person (or character, or archetype) would say, in a given situation. It's predictive software, likely evolved in response to the need to model other chimps in the ancestral environment, and strongly selected for due to the fact that being able to model those other chimps accurately generally paid off big.

It's important to be clear that the experience of "hearing the voices" actually happens, in many people. This is not a metaphor, and it is not hyperbole or exaggeration. I'm not saying that people tend to hallucinate actual sounds—that probably would be schizophrenia.  But in the same way that most people "hear" their own thoughts, people also "hear" the voice of their dad (or "see" his facial expression), offering thoughts or advice or reacting in real time to the current situation.

"I was going to complain about having to type with my thumbs to text you, and how I'd rather just use email or Slack, but my shoulder Malo popped up to say 'Duncan, you have a Mac. Just use Messages with your keyboard.'"

"My mental copy of Jack is currently freaking out a bit about how toxic and unhealthy this sounds."

"I notice my inner Nate is betting this project will fail."

"I can hear my mom reminding me to take jam tarts when jam tarts are offered."

(Note that you don't need to "demand" that your advisor communicate in words! Often it's both easier and also just as useful to simply let them be present—to "see" their facial expressions and body language, imagine their nonverbal reactions, let yourself be aware of and attentive to them in the same way that you (likely) are aware of or attentive to other actual humans in the same room as you.  Think of how, for instance, someone at a party might say something that causes your eyes to dart over to a friend, to see their reaction—you can do the same thing with your simulated friend.)

If you already have this experience: you can curate and improve your council of shoulder advisors, and this post will give you some pointers on how.  If you do not already have this experience: you can most likely learn how to, if you want, and even a weak or limited or unreliable version of the skill has proven valuable for people.

Why would I want this?

In essence: good shoulder advisors allow you to be (at least marginally) smarter and more creative than you-by-yourself are capable of being.

I don't have a rigorous or technically valid explanation as to why, but it is a straightforwardly observable fact that, for many people, their shoulder advisors occasionally offer thoughts and insights that the people literally would not have thought of, otherwise.  Novel ideas, useful perspective shifts, apt criticisms of one's own actions or intentions, that sort of thing.  It's generally well-understood that "two heads are better than one," especially in times when one is stuck or uncertain, and shoulder advisors can be genuinely almost as good.

("One-point-seven heads are better than one.")

Having the right shoulder advisor "show up" at the right moment can be every bit as impactful as having an actual friend or mentor in the room.  And since shoulder advisors take up zero space and can be called upon at any hour and can include people you could never actually call upon in real life (such as Master Yoda or President Obama or Dwight K. Shrute or Mister Rogers or any number of Lannisters), even small improvements in:

• Your ability to summon them at all
• Their richness and overall verisimilitude

... can be tremendously valuable.  My own cast of shoulder advisors have:

• Helped me overcome fear of physical actions I was capable of safely performing (backflips, broad jumps at height)
• Helped me make rapid mood shifts (e.g. yanked me off the path of "I'm about to lose my temper" and restored my perspective and calm)
• Headed off large failure modes in important projects before they cropped up (e.g. pointed out a thing that would go disastrously wrong under the current plan)
• Made genuinely useful suggestions about how to phrase comments in difficult conversations (with employers, with romantic partners, with struggling friends)
• Noticed things that I had not consciously noticed (because it was the type of thing that person tends to care about and pay attention to, and I noticed my mental copy of them noticing)
• Provided advice for other people who were seeking advice from me (that I was incapable of producing directly, out of my own experience)
• Provided genuinely meaningful amounts of emotional comfort and support at times when I was isolated from my friends and family
• Proposed multiple ideas for projects and essays and gotten me "unstuck" on both personal and professional projects
• Generally served as a stabilizer that helps me stay within the range of what "feels like me," i.e. they give me funny looks or helpful nudges when I start acting uncharacteristically or in ways that don't accord with my vision of my ideal self.

... not to mention that having robust copies of my actual friends and colleagues has much better equipped me to interact with those friends and colleagues, by giving me a head-start on how they'll respond to any number of things.

Selection criteria: emulability and usefulness

Step one, acquire shoulder advisors.  Step two, use them skillfully.

This section is for step one.  In order to use shoulder advisors, you have to have shoulder advisors, and whether you're building up a whole shoulder council for the first time or just trying to expand and curate an existing ensemble, some appointees are going to prove much more valuable than others.

Assume you had no preexisting council, and were brainstorming a list of possible advisors with the intent to winnow it down.  You might try writing down four or five names for each of the following categories:

• Close family members (whether they're still close or not)
• Longtime friends (whether you're still friends or not)
• Impactful teachers and mentors
• Current bosses, employers, coworkers, or clients
• Characters from TV shows and movies
• Characters from books or other media (including those you've invented yourself)
• Politicians, comedians, authors, celebrities, and other notable public figures
• People who've blown your mind or changed the way you look at the world
• People you have had serious disagreements with

Once in possession of a list of ~40 names, I claim the next step is to filter it based on the presence of two qualities: emulability and usefulness.

Emulability is the degree to which your brain can, or could likely learn to, successfully boot up a copy of this person and "just push play" on it, such that the copy in a sense "runs itself."  Authors sometimes talk about their characters "coming to life," and producing their own dialogue or wresting the story in an unexpected direction or even verbally arguing with the author inside their head—this is high emulability.  You want the sense that you're not making up or imagining what the person would say, via an act of explicit concentration, but rather that it's just auto-completing in the same way that a catch phrase or advertising slogan auto-completes.

In practice, emulability is often immediately obvious; you can just pluck a name off the list, imagine them sitting beside you (or reading over your shoulder, or lounging on the other side of the room) and just see how they react to what's happening to you right this second, and the claims that they hear me making.

(This is what happens to Hermione above, as soon as she bothers to check.  If attempting to bring someone into your current physical surroundings doesn't work, you could also try imagining specific scenarios, like throwing a water balloon at someone or showing up late to a thing, and see if your shoulder candidate has a characteristic response.)

In the event that this kind of imagination is not yet easy for you, though, there are a couple of qualities you can use to assess the emulation potential of a given shoulder-person, before putting in a bunch of effort.

The first of these is total training data.  People you've interacted with 100x more than average will tend to be more emulable just because you've absorbed more instances of "X happened, and they responded with Y."

(Note that as far as your brain is concerned, it makes zero difference whether the person under observation is real or fictional.  I've seen more of Miles Vorkosigan's reactions to a wide variety of stimuli than I have of many of my actual coworkers.)

The second major component is something like uniqueness or quirkiness or internal consistency.  If someone has a very specific vibe, it's easy to vividly imagine their particular responses.  Ditto if someone has strong opinions, or narrow special interests.

("I saw this video of a rocket launch and immediately thought of you, but then I got this mental image of your face looking very unimpressed, actually, and I genuinely wasn't sure why.  What does real-you have to say?")

Boring(-to-you), quiet, unopinionated, and "normal" people are thus quite hard to emulate, but that's okay because even if you could emulate them, you wouldn't get much out of them most of the time.  You're looking for the kind of people who have the potential to change your course—to think of things you wouldn't, make suggestions that aren't obvious, say the things you need to hear.

Which brings us to our second major filter: usefulness.

When I ran through the brainstorming list above, pretending that I'd never had any shoulder advisors at all, I got about 40 names, and when I filtered for emulability, I had maybe a dozen left.

Predictably, on that list were "Mom," "Dad," and "Ender Wiggin."  But if I were actually creating a council of shoulder advisors from scratch, I wouldn't necessarily want Mom or Dad or Ender to be on it.  I grew up with all three of those people having a deep influence on me—their perspectives and philosophies are already largely baked into "my whole deal," and not the sort of thing I need help keeping in the forefront.

Similarly, I don't really need more Tyler Durden or Mad-Eye Moody; I think I'm doing pretty okay on cantankerous pessimism and niche charisma.

Instead, a far more interesting person to have on my shoulder is one who can remind me of virtues I don't have down pat.  One who can snap me out of my normal patterns, cause me to smack my own forehead and mutter a rueful "of course."

For me, that list looked more like my friend Matthew from high school, who is soft-spoken and charitable and the-sort-of-Christian-the-Jesus-depicted-in-the-Bible-would-actually-like, and Jean-Luc Picard of the starship Enterprise, and an old colleague from Seattle, and the comedian Dave Chappelle.  These people were not only emulable but also truly different from me, which meant that if I could successfully add them to my shoulders, they would have the potential to catch things my regular algorithms would miss.

By "usefulness," then, what I am trying to gesture at is "I suspect my life would benefit from small, well-timed injections of this person's way-of-being."  If you are (according to yourself) too timid and hesitant, then you might look for people who are avatars of boldness, or who tend to be encouraging and supportive and make you feel confident, or who are eccentric and surprising.  If you are (according to yourself) too reckless and unreliable, then you might benefit from shoulder advisors who are avatars of caution, or who tend to pipe up with nervous hesitations, or who are good at noticing the little details before they turn into big problems.

(And if you don't know what your flaws are, or how best to go about improving yourself according-to-your-own-values, then maybe you're looking for people who are generally insightful and clear, or who are good at turning uncertainty into concrete and actionable suggestions, or who are (perhaps) somewhat scathing and unafraid to utter harsh truths.)

Improving the effectiveness of the council

Taking as given that you have some number of shoulder advisors who are either active or who you intend to start consulting, what next?

The key value of a good shoulder advisor is that they say the thing you need to hear, at the moment you need to hear it.  It doesn't take much to tip a tough decision from one direction to the other, or to start (or break) an affective spiral or chain of if-then behaviors.  A shoulder advisor is a specific instantiation of the general wish "if only I'd thought of X before Y happened"—you're trying to make it more likely that you will, in fact, remember X, especially where X is something not particularly native to your current way of doing things.

Taking the second part first, there are two ways to make sure that you hear from your shoulder advisors at the critical moment:

• Build the habit of making an explicit, effortful check; pause and actively boot up your shoulder advisor in response to various triggers, e.g.:
  • You're about to make a major decision
  • You're noticing a strong feeling of temptation
  • You're noticing a strong feeling of certainty
  • You just said a bunch of hateful things about yourself
  • You've just made some kind of absolute declaration
  • You're considering changing the plan (or sticking to a plan you feel an impulse to change)
• "Teach" your shoulder advisors to appear on their own

... there's a little bit of magic in both of these; I'm more telling you where to put your effort and not how that effort should look.  A full attempt to lay out how to build habits-of-mind goes beyond the limits of this introductory primer.

By far, though, it's the second strategy that I and others have found disproportionately impactful.  Explicit, intentional checks can only ever cover a small fraction of the times when people could really use a little extra insight.

However, doing the explicit thing is a good way to bootstrap to the automatic version, especially if you set aside five minutes to do a one-time brainstorm on "when do I wish my shoulder advisors would show up?"  Note that you can make a limited commitment, and that almost any amount of explicit practice will pay off, on the margin—if it sounds like too much to do five checks a day for three months, try doing one check per day for one week (or whatever).

(As with exercise, the best plan is one you'll actually follow through on, not one which sounds virtuous and doesn't work out.  Also, for the record, that line was literally just delivered to me by my shoulder Eli Tyre.)

A couple of tips, as you explore this space:

• Don't ask your shoulder advisors questions.  Just like people tend to get better results from telling themselves "it went wrong" and then letting their brain tell the story of why (rather than asking themselves "what might go wrong?"), it's better to just imagine the person in the room with you—imagine them hearing the previous minute of conversation, or visualize them sitting over in the corner, watching and forming opinions, and just sort of let them say their piece.  This can be a difficult skill to learn, if you don't have experience with it, but be patient—if your shoulder advisor isn't speaking up or making faces or anything, just keep on imagining them as you think thoughts at yourself or review your plan or whatever.
• Also, don't just summon your shoulder advisors to weigh in on Big Issues, especially if you're practicing.  Vary the triggers, and reward your brain for causing the shoulder advisor to show up at all, for whatever reason, even if it's while you're making breakfast or while you're in the shower or just to say something snarky about the person in front of you in line.  Like in (some forms of) meditation, where you don't stop your thoughts from wandering, but rather practice always returning your focus to where you want it, you'll get better results if you think in terms of "how much practice are my shoulder advisors getting at booting up from nothing?"

Once you've got a cast of characters who are willing to show up at all (or at least one solid imaginary friend), then you can worry about nudging their contributions in an actually useful direction.

My favorite techniquelet here is to refer back to the source material.  It's amazing how quickly the human brain will update its model of another human, if you actually go back and check.

"Hey, Nate, I was wrestling with [decision] yesterday, and my shoulder Nate thought the key consideration was [blah]."

"Lol.  I mean, yeah, but actually there's a much more important consideration, which is [blah]."

(Yes, my shoulder Nate actually says the word "lol" out loud, like it rhymes with "doll."  He does this because the real Nate does this, and my brain recorded it.)

If at all possible (especially in the early days), get your real advisors to not only correct your shoulder advisor's core thoughts and ideas, but to flesh out why they think what they think, and where your shoulder copy went wrong/what it doesn't seem to understand.

If your shoulder advisor is fictional, this is somewhat harder to do, but a good substitute is to write down a draft of their first contribution, then review it a day or two later with a critical eye.  Even moreso than copies of real people, your fictional shoulder advisors are free to mutate in whatever direction is useful for you.

(One thing I've had fun with is pitting them against each other—not by simulating an argument directly, where I imagine two sides of a debate, but rather by having both of them fight to convince me, or by having each of them arguing their conflicting judgment of the situation.  Having an optimist and a naysayer is a pretty good dynamic, and it's not hard for most human brains to pattern-match what each of those would say next, to the other.)

Ultimately, the idea is to give regular feedback to whatever part of your brain is running the emulation.  Upvotes for what works and feels true, downvotes for what doesn't, but most importantly, more training data.  It's fine if your shoulder advisor gets frustrated and impatient as you ask it to say more and more words—let it be frustrated and impatient in whatever way is characteristic for that individual, and just keep recording.

Downloading yourself

Again, the above was more a set of trailheads or threads-to-pull; there's not really a standard canon of advice here yet.  Hopefully, it's enough to get people started (and hopefully readers will leave further tips and advice in the comments).

There was one last piece of the overall picture that I wanted to touch on, at least briefly, and it's this:

You, too, can be a shoulder advisor.

My friend Nate and I both live in each other's heads, and we both furthermore have a vested interest in our mental clone copy.  Nate wants my shoulder Nate to be as good of a Nate copy as it can be; I want the same for his mental Duncan.  In part, this is for weird TDT-esque considerations, but mostly, it's just because I like my friend Nate, and he's my friend at least in part because of the impact I have on him, and if he's got a copy of me on his shoulder I can go on having that impact even when I'm not actually in the room.

You can in fact deliberately install yourself in other people's heads, if they're at all inclined to let you; some of my best lectures while at CFAR included me doing exactly this.  The key, as with developing your own shoulder council, is to focus on making yourself emulable.  Making your outputs reliably generable from inputs, having a specific and legible style or vibe.  If you've only got an hour, this usually means being pretty blunt and repetitive and keeping things simple:

"... so the one question I want you to keep asking yourself is 'do you know what you are doing and why you are doing it?'"

[5 minutes pass]

"Say it in my voice, in your head: 'Do you know what you are doing and why you are doing it?'"

[10 minutes pass]

"And what would Duncan say, at this moment?  Can you picture his face? ... that's right, he'd say 'do you know what you are doing and why you are doing it?'"

[40 minutes pass]

"... months from now, you're going to be sitting in your room, tired and frustrated, and you're going to look up at the clock, and you're going to sigh, and then you're going to hear my voice in your ear, and it's going to say—"

By this point, I get a message roughly once a quarter, from former students or former workshop participants or people who saw me at a conference or talk, letting me know that their shoulder Duncan appeared for them in a pinch, and that they were (usually) quite glad that he did.

If you have more than an hour to interact with someone, you can be a bit less cheesy than the above example, and encourage the same sort of feedback loops I described earlier, from the other side—Nate, for instance, often asks for the specific wording of his shoulder advisor, if I can remember it, and remarks on that wording as if he were disagreeing with shoulder Nate in a casual conversation, correcting and improving it.  

(It's just such little mannerisms that allow a shoulder advisor to be "really real"—to bring it to life, give it a personality separate from, and not dependent on, your brain's main central personality.  Again, I don't have a sound explanation of the mechanics, but it works.)

You can often make this happen by simply asking your friend or colleague or coworker to predict what you'll say, in response to a given question or prompt—

(Asking them to predict is in general better than asking them to guess.)

—and as icing on the cake, this has the added benefit that, not only are they refining their specific model of shoulder-you, they're also secretly practicing the general skill of booting up a shoulder advisor at all.

Speaking of which ...

Recap & Conclusion

This section is left as an exercise for the reader—try booting up a shoulder Duncan and see what parting words he has to offer, before you (hopefully) leave a comment down below.  And if your shoulder Duncan doesn't have anything at all to offer, see if anyone else feels like chiming in.