FAQ

What counts as unexpected?

I'm measuring surprise, which is related to probability but not identical to it.

Before the party, I have a mental model of everyone I know and have ever met. For each person, there's an implicit probability I'd assign to "will they attend?" Low probability is necessary for surprise but not sufficient. Two people with equally low probabilities can produce different levels of actual surprise.

Surprise also depends on: how emotionally significant you are or were to me, how deep of a revision your presence requires to my understanding of things, whether I had actively considered you and rejected the possibility vs never thought of you at all, and why you were improbable in the first place. Someone I thought disliked me showing up is different from someone who just lives far away showing up, even if both had the same low probability. The first requires me to revise something about the relationship. The second just means you booked a flight, which is still significant but is a different category.

The probability estimates come from:

1. My perception of the relationship. How close I think we are. Whether I think you'd want to come. Whether I think you think I'd want you to come. Whether I think you'd feel invited. Whether I believe you like me, are neutral toward me, or dislike me.

2. Your personality as I understand it, or my lack of understanding due to distance or time. Whether you attend things in general. Whether you attend things like this specifically. Whether you're the type to prioritize social obligations. Whether you're introverted or extroverted. Whether birthday parties are something you do.

3. Practical constraints. Where you live. Whether travel is feasible. Whether you have time. Whether you have money. Whether you have other obligations. Whether your life circumstances make attendance difficult.

4. Communication. Whether our communication suggested you would or wouldn't be here for this. If we haven't been in each other's lives for a long time, I might have no data here at all, which is itself a kind of input. If you're seeing this, this is the invite. It does not matter how long it's been since we last spoke or what terms we were on.

Some implications:

Time since last contact is not itself a factor. It only matters insofar as it affects my probability estimate. If I haven't seen you in ten years but you're the type who shows up to things, I'd expect you. If I saw you last week but you never come to anything, I wouldn't expect you.

Geographic distance is not itself a factor. It only matters if it made me assume you wouldn't come. If you live in another country but I knew you'd fly in, you're expected. If you live nearby but I assumed you wouldn't bother, you're unexpected.

Relationship closeness is not itself a factor. Close friends can be unexpected. Acquaintances can be expected. Relationships are multidimensional. Close vs distant is one axis. Good terms vs bad terms is another. How often we talk, how well I think I know you, whether there's unresolved history. Any of these can affect my probability estimate. The question is not where you fall on any single axis but whether I predicted your attendance.

Some scenarios that produce low probability estimates: I forgot you existed entirely. I assumed the relationship had ended. I thought you were upset with me. You never attend social events. You live far away and I didn't think you'd travel. We only knew each other through a specific context that no longer exists. You're from a different social world where this wouldn't be normal. I invited you but didn't believe you'd actually come. You're someone who typically assumes they're not wanted, so I assumed you wouldn't come.

The calculation is based on a combination of my immediate internal reaction to seeing you and a lingering consideration of how surprised I feel about your presence compared to everyone else who attended. The internal reaction is separate from any physical factors of your arrival. Coming in with a cake, screaming happy birthday, making a loud noise, or anything theatrical will not factor into my reaction. If you told me in advance you were coming, that updates my probability, and you become more expected. If you show up without warning, the full gap between my prior estimate and reality is preserved.

What doesn't count?

Physical surprise. Jumping out from behind something, saying boo, wearing a disguise.

An expected person doing something unexpected. If you're someone I fully expected to attend but you arrive in an unusual way or bring a strange gift or do something weird at the party, that doesn't make you unexpected. You're still expected. You just did something surprising while being there.

A stranger I have no awareness of. Surprise requires a gap between expectation and reality. If I've never heard of you, I have no reason to expect or not expect you, so there's nothing to measure against. This is different from someone I know of but don't have a relationship with. For example, I would not expect a celebrity who doesn't know who I am to show up, but that expectation still serves as a model that allows surprise to exist. However, if a friend is friends with that person, it could increase the likelihood that they show up, which would make it less surprising because the probability has increased, assuming this is a relationship that I knew about.

What if my attendance makes things awkward?

I don't know who might show up or what it might feel like when they do. It's up to you to decide if you're comfortable attending.

What if I'm already expected?

There are always ways to make yourself less expected. Also, there will be an extra something for you if you were responsible for referring the most unexpected person.

What if no one surprising shows up?

Someone still wins. It's not "most surprising person ever," it's "most surprising person who attended." The prize goes to whoever surprised me most, even if that surprise wasn't particularly large.

What if I'm so surprising that you forget I was there?

I'll be wearing a sweatshirt with a QR code on it. When you scan it, it will take you to a page on this site where you can take a photo of yourself and upload it to a gallery with your name.

Who decides?

Me. But I will be relying on the accounts of others as a secondary point of information to determine how surprised I was in the moment. The final decision will either be at the very end of the night or the next day.

Isn't this stupid and a waste of money?

Here are some things that cost $500: a weekend trip, a ski day, a really nice dinner for two. One time I tried to pay my car registration via a cashier's check that I put in the mail. It was $200 and I realized after I left the post office that I forgot to write anything on the envelope. At one point I was considering renting some sort of space for this party, which would mean giving money to a landlord I had never met in my life, so this seems like a better idea.