Design by Numbers: Simultaneous Perception

Posted on January 30, 2012 by rewardingplay

Perceived Simultaneity Threshold: 100 milliseconds

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

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.

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.

Elephants, on the other hand, NEVER forget

Design by Numbers: Cooldowns

Posted on January 9, 2012 by rewardingplay

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.

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.

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.

Design Sense – Perception

Posted on May 27, 2011 by rewardingplay

Rorschach Tests

Look at this picture. What do you see?

The answer is obviously Goro

Hermann Rorschach devised the technique of using random ink blots to probe the subconscious mind, based on the idea that patients would be prone to seeing images that were more important or relevant to their mental state. They would project their internal preoccupations onto the otherwise abstract shapes, revealing clues that could be deciphered by their psychiatrist.

The reason ink blot tests work is because humans are naturally adept at seeing images and patterns. Our brains are composed of an enormous collection of highly specialized neural circuits, custom-built for finding, storing and matching patterns. Parts of our brains are devoted to sensing contrasts, finding parallel lines, extrapolating three-dimensional depth, recognizing faces, anticipating motion — the list goes on and on. In fact, so much of our cognitive potential is tied up in neural pathways that are optimized for matching specific patterns, it is actually very difficult to avoid seeing them everywhere. In video game terms, you are almost all GPU with very little CPU. It is difficult for us to simply perceive information without our specialized capabilities biasing our interpretation of it.

Completely abstract shapes

This is great for surviving in the jungle, not so great for designing games. The problem is that we begin processing before we have all the information; we draw conclusions based on patterns that may not actually exist. Did that element dominate an encounter because of a fluke, or does it represent a trend? Is this feature a little out of tune, or does it hopelessly conflict with the rest of the game? It’s impossible to tell from a single example, but that doesn’t prevent us from making judgements based on one experience. And once we have a pattern in our head, Confirmation Bias kicks in and our brain optimizes further and starts rejecting data that doesn’t support our initial conclusion, making it even harder for us to be objective.

Confirmation Bias is especially potent for game designers, because we know what is supposed to happen. We wrote the paper design, we know how a mechanic was intended to constrain the gameplay, so we play our games as if the mechanics work properly — even when they don’t! We know the picture behind the ink blot, so we are incapable of seeing with unbiased eyes. Which is why we are so often shocked during playtests; what is obvious to us proves unintuitive and confusing without the pattern already in mind.

Unfiltered Perception

So train yourself to see the ink, not the pattern. Stubbornly stare until you don’t see an image, but only what is truly there. Then, when you play your game, divest yourself of preconceived notions of what the game ought to be and strive to experience the game as it truly is. This will allow you to see through the eyes of a new player.

Another method is to find Gestalt images, pictures that abruptly change meaning based on how you look at them, and practice switching between the competing interpretations. This will allow you to hold multiple explanations of the same game experience in your mind at the same time, so you can evaluate them all fairly.

Old woman, young woman, old woman, young woman...

It may sound ridiculous to spend time deconstructing smudges and turning old women into young women, but it will help reclaim some of those specialized circuits and increase your ability to process unfiltered reality. Which will make you a more effective game designer.

GDC 2010: Design in Detail II

Posted on February 18, 2011 by rewardingplay

In order to develop a sense of balance, you need to understand how your brain works. You have an Orbito-Frontal Cortex; It’s called that because it is located behind your eyes, but it’s really your Gut. When you learn something new, it goes through a process where it builds a model of the world and makes predictions about that model. If it is right, it releases Dopamine, which cements the model a little bit.

If you are a designer, you need to familiarize yourself with how this process feels, because your ultimate goal should be to get the game inside your head. You want the model in your gut and the game in the world to be the same. You should be able to predict how the game will play in a given situation before actually picking up the controller.

Ok, back to Halo 2. We had to patch, even though we didn’t want to. Patches are risky and expensive. Luckily we had network bugs, so we were going to have to patch anyway. (I’m not sure we would have gotten to patch Halo 2 strictly for balance changes; I’m glad we didn’t find out.)

Choosing what to patch was harder. You want to tweak everything, but you can’t because then testing gets out of hand. Games that have the ability to easily change the gameplay often over-patch fopr precisely this reason.

Choosing what NOT to patch was hardest. We didn’t change the Sniper Rifle because it was right below the line of what we could safely re-balance

Which brings me to my final theme: Make the hard choices. Balancing is hard because it requires you to do things you don’t want to. And it is tricky because there are so many ways to confuse or talk yourself out doing it properly. But the worst thing you can do is leave the decision up to chance because you can’t make a tough call.

Why are these choices hard? Again, the answer is your brain. You also have a Pre-Frontal Cortex. It’s called that because… Who knows? We call it your brain.

It is a poor tool, but it’s what we have. You can’t reason out everything, in fact you can’t reason out very much at all. There are so many ways that your logical mind has to trick you. You must confine yourself to reason on the detail scale. You just can’t hold enough factual information in your brain to make rational decisions about very complex situations.

Radiolab is a great show on New York Public Radio. They have a podcast, you should subscribe! In an episode called “Choice” they describe this experiment where psychologists give people a number to memorize, 2 digits to 10 digits. Then they send them to another room to repeat their number. On the way, they have someone interrupt them (All good psychological tests are about fooling the subjects) and ask them if they want an Apple or some Cake.

The people with short numbers pick Apples at a high rate; Apples are better for you, fewer calories, watch your waistline. Those trying to remember longer numbers more often choose Cake. They are so busy with numbers, they make the decision emotionally.

That’s right, 7-10 numbers are enough to completely fill your rational brain! My high school calculator had more horsepower than that!

So when you have to think rationally, think about details or you will get hopelessly lost. And fat.

Ok, here are the four themes of my talk:
– Balance is longevity
– Balance in passes
– Develop your sense of balance
– Make the hard choices

I am going to use these themes to explore the Detail. Now let’s get to the Sniper Rifle!

[Continue]

Definition: Habituation

Posted on February 11, 2011 by rewardingplay

Habituation

The gradual reduction in sensitivity to a repeated stimulus

I got my teeth professionally cleaned this morning. (One cavity, apparently I need to floss more.) Now I cannot stop running my tongue back and forth over the newly polished enamel. When I woke up today, my teeth were the farthest thing from my mind, unnoticeably insignificant. But now I am obsessively, subconsciously, exhaustively exploring every crevice and gap. This is a side-effect of a neural process called habituation. As a stimulus (like “I have teeth”) is repeated, the electrical and chemical impact of the experience physically decreases to the point where it drops out of conscious thought, and then subconscious awareness, and eventually it is not felt at all.

You can get used to anything

As a human, this is a very good thing. Imagine trying to have a conversation while consciously aware of the sound of your own heart pumping, the movement of your lungs breathing in and out, every blink interrupting your train of thought, unable to stop noticing the pressure of the chair into your back or ignore the ambient noise of other conversations. It would be impossible to function. Habituation allows you tune out the vast majority of unimportant details and focus on what is new and interesting, like how smooth your molars have become. It’s a miraculously efficient process that allows our embarrassingly under-powered brains to filter enormous amounts of sensory information.

As a player, habituation is what allows us to learn to play a game and subsequently master it. Our ability to predict future events based on current conditions is inseparably dependent on our habituation to past events. A chess master learns to ignore the thousands of poor, but still possible, potential moves and consider only the strategically significant ones. A skilled Halo player moves through a multiplayer map without thinking about it, using all of his attention to scan for his opponents. When Mario reaches the edge of a ledge, pressing the “A” button always makes him jump. If chess pieces could move randomly, or a Halo map suddenly had a dead-end instead of a corridor, or the “A” button threw a fireball, the player would be unable to play the game effectively.

Alternative ways to make chess more interesting

But as a game designer, habituation is your mortal enemy. A tireless, inexhaustible foe, mindlessly obviating the best efforts of your craft, which you can only hope to delay, but never defeat. Fun gameplay is an interactive experience, and habituation inevitably reduces every experience to meaningless static. To some extent, the purpose of every design trick and tactic is to disrupt habituation, to resensetize players to the fun experience and help them continue to enjoy the game. We are hacking our own mental hardware, making it less-efficient.

The truly nefarious nature of this enemy lies in how sneaks into the design process itself. Designers can learn to ignore glaring problems that would annoy or aggravate a new player. Or they can overlook logical loopholes that will wreck the game balance because they are familiar with how the game is “supposed” to be played. Or they might wrongly believe an element has been properly tuned because they are no longer sensitive to the effect it has on gameplay. Understanding and controlling habituation, both their player’s and their own, is a crucial design skill.

Rewarding Play

by Jaime Griesemer

Tag Archives: neuroscience