A hair lip?

Design by Numbers: Simultaneous Perception

Perceived Simultaneity Threshold: 100 milliseconds

Let me tell you how I got my nickname, Jaime “Three Frames” Griesemer.

A hair lip?

Emily "Three Frames" Crazyhair

We were working on the melee animations for Halo 3, trying to get the timing right. There were already fast. Like, blink-and-you’ll-miss-it speed. The animators were having trouble because there wasn’t enough time to add a sense of anticipation and sell the impact properly. And for some unknown reason I wanted the damage keyframe to happen faster. “The melee animations can be as long as they need to be… as long as they’re exactly three frames.” We went back and forth about it, but eventually I traded three frame melee attacks for some extra flourish on the recovery after the hit. Everybody was happy.

Until the next day when I went back to try the new melee animations. I picked up the Assault Rifle. I pressed the B button. Three frames later, the butt of the rifle crunched into the face of a helpless alien invader. I picked up the Plasma Pistol. I pressed the B button. Three frames later, my left hook connected with a random marine that was looking at me funny. I picked up a shotgun. I pressed the B button. And for some unknown reason it didn’t feel right when I cracked open the head of a passing parasite. “Wait. That wasn’t three frames. Yeah, I’m sure, check the file. See… four frames!” (In hindsight, I’m lucky my uncompromising design demands didn’t earn me anything worse than a mocking moniker.)

What was the unknown reason? How could I tell the difference of only a single frame? Why did I insist on the speed at the expense of animation quality? The answer lies in our physiological limitations. What we experience as consciousness — as a stream of consecutive events in a clear and tidy order — is not nearly so neat. It’s a cacophony. A discordant mess. Your senses collect an incredible amount of information; they’re always on, always filling your nervous system with an unrelenting torrent of unfiltered data. It comes in at different speeds and at different times. The visual part is heavily processed, so it comes in late and is usually out-of-sync with the rest of your senses.

Change your mind?

Your brain at work

Your brain is used to this. It is, in fact, extremely good at taking all that information and combining it into a coherent experience. So good, it can take distinct events and merge them. Asynchronous events like pressing a button and seeing a melee attack. This feeling of simultaneity greatly increases the player’s connection with the action on-screen. Instead of a second-hand signal that transmits their intentions, pressing the B button becomes the act of dishing out a knuckle sandwich. But that requires your brain to blur over the delay and merge the movement of your thumb with the satisfying crunch.

Below a certain time threshold, the brain takes two events that are functionally separate — one causes the other and could not happen at the same time — and gives the impression that they were simultaneous. It turns out that threshold is around 100 milliseconds, or a little more than three frames. The reason four frames felt wrong was because the events were experienced as distinct, disassociated actions. The extra time allowed my brain to distinguish between them, in a sense inserting the controller as a step in the process and reminding me that I was not actually the one wearing metallic boxing gloves. So, for games where it is important to give the player a feeling of direct control, be careful of crossing the 100ms threshold.

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Elephants, on the other hand, NEVER forget

Design by Numbers: Cooldowns

Maximum Cooldown Time: 6-12 seconds

Purple hippos. Green puppies. Red monkeys. Short term memory is an interesting thing. Yellow birds. Blue horses. It can only hold around seven items (give or take a few, depending on your level of concentration.) Which means for some of you “Orange lizards” is going to drive the first animal right out of your working memory. This is why most game controllers have around seven buttons — White spiders, Pink fish — and most successful action games don’t even use that many. Player’s simply can’t hold all those options in their heads at the same time.

Elephants, on the other hand, NEVER forget

Orange elephants.

But the most important aspect of short term memory isn’t how many options player’s can remember, but how long it takes for them to fade. Or how short. Neurological research indicates that we start to forget details as few as 6 seconds after being introduced to them. After 300 seconds we are only half as likely to remember a concept, and after 10 long minutes… forget about it. (Sorry.) So that means, depending on your reading speed, you’ve almost certainly forgot the first animal by now.

This has a direct application in determining the length of cooldowns for abilities in action games. (In this context, a “cooldown” is the amount of time that must elapse after an ability is used before it can be used again.) The player stores the fact that an ability was used in their short term memory, and if the cooldown doesn’t expire before they forget about it, they may never use it again! It sounds preposterous, but how many times have you seen someone go through a tutorial on how to use an ability, use it successfully once or twice and appear to understand how it works, and then get utterly baffled when required to use it again just a few minutes later? How many times has that happened to you when playing an unfamiliar game? I know it has happened to me more times than I can remember. (Sorry again.)

So, if a cooldown prevents a player from using an ability for more than 6 seconds, there is a risk that they will stop using it entirely. An onscreen indicator that a cooldown has expired helps, but habituation and change blindness limit how effective an indicator can be, especially when it changes very rarely. Repetition helps, because it transfers knowledge of the ability into more permanent memory, but even this is tricky because with a long cooldown what the player will be committing to memory is the fact that the ability is unavailable, making them even less likely to use it. The options, then, are to use very short cooldowns — between 6 and 12 seconds — or rely on a very noticeable reminder when ability is available again.

You missed a spot.

Indicators have their own problems

For an action game, where onscreen indicators are not desirable, long cooldowns lead to mechanics that are often ignored and quickly forgotten. Maroon walrus.

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Year One: Uncharted Pornography

Last year I wrote about balancing multiplayer weapons, why I’ll never make a free-to-play game, the best way to exploit platform achievements, and 70+ other topics, but the ones that stirred up the most traffic were giving a 7.5 to Uncharted and “pornography games“. Well, that and when neogaf found out I had left Bungie. You can read all about the hits and misses in my yearly blog report.

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Find what you were looking for?

As you can see, I started the year out strong, largely due to my unexpected retirement, but faded when I got my new gig at Sucker Punch. Turns out starting a new job is a lot of work! But I’ve hit the six month mark (so I can start slacking off) and I’m thinking about updating the site more frequently — hopefully once a week. I’ll be making shorter posts on more narrow topics, which will probably make them more useful to the handful of game designers that read the blog, anyway. You can expect the first new content in the next few days, provided I can resist the pull of more Dark Souls.

Smile for the camera, Toothy!

Who could resist that pretty face?