Deathtrap Design and the Invisible Gorilla

It was a viral video going around for a while — the Invisible Gorilla experiment. (If you never saw it, you can watch it here… the rest of this blog-post is a spoiler!) (Although to be fair, just saying the words “invisible gorilla” is a spoiler already… oh well.)

This experiment from 1999 was quite astonishing. Framed as a test, the video asks you to count the number of times some kids pass a basketball back and forth. Partway through, a person wearing a gorilla suit saunters into the video, mugs right in front of the camera, plain as day, and leaves. In the experiment, fully half the people who watched this video did not notice the gorilla. They were too busy counting basketball passes.

None of those people would believe they could miss a friggin’ gorilla. When the gorilla was pointed out to these people, some insisted that the experimenters had switched the tape! They pretty much universally said “of course I would see a gorilla.” But yet, half of them were wrong. The new book by one of the authors of this experiment is engaging and worth a read.

If you didn’t see the gorilla in that video, you aren’t stupid. Even after many experiments, the researchers couldn’t find any way to predict the people who would notice the gorilla (or whatever other random thing they added, in any context). Regardless of the experiment or the person, some people notice the external details sometimes, and sometimes they don’t. But people always think they will notice all major details. Worse, when they see somebody not noticing an important detail, they assume those other people are idiots… even though it’s just dumb luck that they noticed it themselves.

EDIT (bonus paragraph): the first thing commenters say is “well, but the gorilla blends in!” That was the first thing the psychologists assumed, too. I’ll give you that they are psychologists, but in this particular case that doesn’t mean they’re completely stupid. They tried numerous additional experiments, including, for instance, one where you are supposed to count the number of small black digits floating by in a big white empty screen. Then a gigantic red letter E flies by. Half the people still missed the giant letter. It doesn’t matter what the context is, and it’s not about something blending into the noise. Even incredibly distracting interruptions will still get tuned out. That’s why this is an interesting phenomenon.

We have a highly-ingrained belief that we notice everything around us, but the truth is that we have very selective attention. When we’re focused on something else, we often miss very obvious things in our surroundings. But we believe only idiots would do that.

This is the crux of the book, although it unfolds into a lot of other interesting experiments and diversions. The authors are concerned with how this affects our court system, among other things. I am more concerned with how it affects the games we make.

Instant Death

It’s an MMO designer classic: stick some giant horrific monster into an area to keep players on their toes.  If the players refuse to run away from said monster, they get killed. But they always have plenty of warning. “The earth shakes when the giant walks,” says the designer — “they can’t help but notice that! So it’s not unfair. It’s just something to keep them on their toes.” Or how about the old “random firetraps in the middle of a raid dungeon” trick? Spices things up without being unfair, right?

Unfortunately, half the time these sorts of encounters end in unavoidable death. The players are deeply engaged in playing the game — watching the little bars tick down and using the right skills at the right time — and half the time, they miss your deathtrap cues, no matter how obvious you think they are. When they die, they are understandably upset.

The really frustrating part is that other players think they’re morons. Hell, the players themselves often come to think they’re morons. “How did I manage to get ganked by an elite cavalry unit when you can hear the horse steps a mile away?!” The general conclusion seems to be that the average MMO player is really stupid. Right?

"You Automatically Lose" Community Chest Card

Caption: Unpredictable instant death is not a fun game mechanic.

But in actuality, designers are being just as misguided as the players. Most designers would agree that it isn’t fun to die instantly without any warning. But yet half the time, these “easily avoidable” deathtraps go unnoticed. There’s nothing the players could do to pay more attention. It’s not possible to focus on the gameplay and also notice 100% of the other stuff going on all the time.

The result is that half of those kills are insta-kills without any warning. They are the antithesis of fun. Worse, other players often make fun of them for something they couldn’t avoid. What a stupid thing to include in an MMO!

To HUD or Not To HUD

A related study referenced in the book looked at pilots being trained to use new HUD systems. The pilots would get so transfixed managing the HUD data that they would miss things going on out the window — things happening literally underneath the translucent HUD, or just an inch away from it. It’s not about visually missing something, it’s about our brain completely filtering things out as noise.

We’ve all played games where the GUI was more important than everything else going on. Hell, I still have no idea what the 3D characters do in Rock Band — I can never take my eyes off the fretboard GUI long enough to notice anything.

Among designers who have learned about this psychological phenomenon, there is a tendency to try to integrate the gameplay right into the world. (I have often been in this camp, with mixed success.) For instance, in Red Dead Redemption there is no health meter. The screen just gets redder and redder as you are about to die. I find that this does make it easier me to focus on the world around me instead of constantly glancing at that damned health bar… but on the other hand, I am often surprised when I suddenly keel over dead. (I can hear you thinking “But the screen turned bright red! How could you not notice that! Oh… wait, right.” Just because it’s impossible to miss doesn’t mean we won’t miss it anyway, half the damned time. HALF THE TIME!)

How Do We Fix It

The authors of The Invisible Gorilla want to make you aware of the fact that your attention is extremely selective — that you are missing crazy things happening around you all the time. That is a great thing to teach people, but that’s not the role of video games.

Most video games (including the ones I like to make) are escapism, much like books or TV. Here, we want you to feel good about yourself. We don’t want to teach you that your brain can miss important things going on around you — instead, we want to hide this flaw in the human brain. When you’re playing a video game, you shouldn’t be surprised about unfortunate outcomes. You shouldn’t go “How did I die?!” or “Where did that level-80 elite mob come from!?” Those questions indicate that the player is feeling abused. Moreover, they aren’t learning anything, either (except, perhaps, not to play your game): it is not possible to “learn to pay more attention”.

The only band-aid fix is not to have nasty traps like that in your game. That isn’t really a deep “fix”, though, because the problem happens with rewards, too — I mean, you are probably running past tons of ore mines, rare monsters, spontaneous treasure chests, and who knows what else, without ever noticing them. On the one hand, that stuff didn’t kill you, so it doesn’t hurt you. On the other hand, designers didn’t factor in that you would miss half the stuff they stuck in, so the game may feel more sparse and empty than they expect… because if you’re focusing on combat, you are literally missing half of the cool stuff around you.

More Research

Until reading this book, I didn’t realize that psychologists have done quite so much research on selective attention. The book is obviously not too concerned with video game design, but I’m hopeful that there are experiments by human-computer interaction psychologists that may help us understand how to work with this issue when designing games. If I find some, I’ll post about them. (And if you have leads, please share them!)

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34 Responses to Deathtrap Design and the Invisible Gorilla

  1. Ben says:

    Something that inherently makes the invisible gorilla test unfair is half the participants are dressed in black. When the person in the gorilla suit appears on screen, the suit is also black, so it is ignored. I would like to see that test redone with the gorilla suit in bright pink.

  2. Eric says:

    They did repeat the experiment in many varieties and contexts, with no difference in results.

  3. darkeye says:

    That makes me think again about how successful the event system in GW2 will be. The developers already gave an anecdote about how the testers seemed to be running past content that *should* have been obvious, like a poisoned field with huge slugs. If players treat it like a conventional themepark game, with a blinkered approach following the main storyline, it’s going to be a lot more than half missing out on the *obvious* and complaining of a lack of content, or the unfairness of strumbling into the midst of an event and getting clobbered by missing the group of players that are working together at it. That said I’m looking forward to see how it turns out.

  4. Stabs says:

    It’s inevitable that attempts to analyse and explain fun will lead to reductionism. Let’s take an element out of the context of the rest of the game and look at it. It’s not sound.

    In WoW at least two areas used this mechanic including Silverpine Forest which had high level elite werewolves and Hellfire Peninsula which had giant, ground-shaking, demonic robots. And I can certainly attest to being killed by these “invisible gorillas”.

    But what they do for the game is something a theme park game would otherwise be somewhat lacking in. They emphasise player story (characterised by Bartle as “I fell off Weathertop” ) which is something players absolutely love. Instead of “I went to HFP and did 80 quests” players remember “I went to HFP and got ganked by that effing robot”.

    They break up the monotony. And because players can’t believe it’s not their fault they don’t see it as a contrived mechanic in the way they saw attunements for places like Karazhan (which were obvious).

    Instant unexpected death may suck on its own but it’s absolutely part of the WoW experience when you view it holistically. You may not like the colour yellow but you can still like the Mona Lisa even though it contains yellow.

  5. smakendahed says:

    Very cool. But you can’t dismiss the people that actually like having those invisible gorillas out there for a number of reasons, mostly because they see them while others don’t. It adds something for them.

    And I do think people learn from it and can become more aware in game. I’ve seen big turn around with people that previously died too easily by standing in fire or void zones or puddles of goo. It also adds an element to communication where the more aware people often end up leading things and warning others.

  6. Garumoo says:

    > even though it’s just dumb luck that they noticed it themselves.

    Funny you should say that – another researcher has established a link between perceptiveness and apparent luck. People who feel they’ve been lucky are generally more perceptive, and would likely be in the group that saw that invisible gorilla, while people who have a history of bad luck are the opposite.

    Have a read of this for some fascinating experiments he conducted:

    > it is not possible to “learn to pay more attention”.

    Ah, that same researcher would argue the point, and that it is in fact possible to learn to pay more attention. I’d like to see more rigorous experiments before being convinced, but the possibilities are very interesting.

    As he says:
    “I asked a group of lucky and unlucky volunteers to spend a month carrying out exercises designed to help them think and behave like a lucky person. These exercises helped them spot chance opportunities, listen to their intuition, expect to be lucky, and be more resilient to bad luck.”
    “One month later, the volunteers returned and described what had happened. The results were dramatic: 80 per cent of people were now happier, more satisfied with their lives and, perhaps most important of all, luckier.”

    Which prompts a fascinating thought – could a game be designed to teach and reward those attitudes and skills, and consequently train the player to be more lucky in life in general?

  7. JeremyT says:


    You say it was done in “different contexts,” but do those contexts involve interlopers of dramatically different size or color?

    Just based on my own experience, a large part of what makes the gorilla difficult to detect is how well it blends in with the black clothed players (who I’ve discounted as “noise”). In fact, they’re all just people wearing black clothes, the gorilla’s clothes are just fuzzier and he happens to be wearing a mask. If you’re not looking at him directly it seems like it would be very difficult to pick up on that, so you pretty much have to rely on his different motion to draw your attention as he crosses the stage.

    I have a lot of trouble believing that *degree of contrast* isn’t critical here, and that video looks specifically engineered to obfuscate the gorilla’s presence.

    Of course, I also don’t think that this discounts the basic premise: people who are absorbed in something will miss subtle cues. But then, isn’t the solution to make those cues less subtle? The huge, random ganker mob thing is usually only a surprise when it comes up from behind, when you lack an obvious visual cue. The “shaking ground” bit is the kind of thing you’d be likely to discount as noise, as there’s all kinds of irrelevant motion going on in combat, but the huge fricking monster visibly in front of you? I really don’t think you’re going to miss that nearly as often.

  8. JeremyT wrote:
    Just based on my own experience, a large part of what makes the gorilla difficult to detect is how well it blends in with the black clothed players (who I’ve discounted as “noise”).

    I think this is an important point. The video linked in Eric’s post asks people to count how many times the people wearing white pass the ball. The video has a lot of motion going on, and a typical person is going to have to focus a lot on the people in white to keep track of their passes and not get them mixed up with the passes from the people wearing black.

    I still think there’s a game design lesson here, but perhaps not quite as strong as Eric is thinking. Consider in EQ1, the first instances of the “deathtrap monster” that I remember: the griffin in Eastern Commonlands (EC). The big problem was that you were mostly fighting enemies on the ground and had to pay attention to them; you might not be used to even thinking about flying enemies like the griffin, so when it swooped down and ate you in a bite or two, it was really surprising. WoW did a better job of making the deathtrap monster so huge that was more difficult to miss it.

    I think the issue here is what I call “hyperfocus”, which from my experiences seems to be pretty common between the geeky programmer types that make up a lot of MMO players. What happens is that you focus on something to the exclusion of anything else. My better half got really annoyed when this happened a few times, usually when I was working on some programming project. She’d say something to me and I’d give some sort of automatic reaction that made her think I was listening to her. Turns out, I was 100% focused on my work and not her. I suspect this is the same thing: your attention is always bouncing between staying with the enemy, noticing your own health, and managing your ability cooldowns; when something sneaks up behind you and eats you alive, you think it came out of nowhere.

    My theory, at least.

  9. Dblade says:

    I’m wondering why this is such a surprise to designers. You have a healer that has to focus all of his attention on tank health level, his MP health level, the HP level of the entire party, when to rest, when to remove status debuffs, and maintaining the proper spacing to avoid AOE. Of course they are going to miss links. You aren’t counting a ball being tossed, you are counting it while doing math sums and talking on your cell phone. And all the while dealing with the visual strobe effects of a game.

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  11. Andrew says:

    Oh hey – WordPress automatically notified your blog. Please feel free to delete my last comment (and this one)

    Sorry to spam!

  12. Sandra says:

    @Garumoo: That’s an interesting article that you linked to, but I’m not seeing the same connection that you are between that research and the selective attention research. You can make the argument that one of the four basic ‘lucky’ principles — creating and noticing chance opportunities — is related to selective attention, but the research points much more strongly to a difference in perception, not attention. And those are not the same thing … not as this researcher is using them.

  13. Eric says:

    @JeremyT, @Brian ‘Psychochild’ Green: some of the other contexts were, e.g. “here’s a video of some small black and white numbers floating across a screen. Count the number of ‘2’s.” And then a giant bright red E flies across the screen, and people still miss it.

    The very first thing the psychologists assumed was that the gorilla was blending into the noise, so their next experiments tried to correct for that. The reason this book is so startling is that it has nothing to do with contrast levels.

  14. Eric says:

    @Stabs: Gotta say, I hate the living hell out of that theme park ride. If I never get stepped on by another giant, I will not be sad. And no, occasionally making me sad does not make it more fun overall. I don’t get your “color yellow” analogy; here’s a better one. I invented “getting punched in the gut movies” — when the character on the screen gets punched in the gut, so do you! Even if you hate getting punched in the gut, you can still enjoy my movies… it’s part of the holistic experience. Sounds moronic, right? Say, how about we remove the gut punch and then see if the holistic experience gets better or worse?

    Okay, we can run with the color-yellow thing, too. If I hate a particular color, why not give me a Mona Lisa in another color? Is it really that hard to think up a replacement, or are designers just too damned lazy?

  15. Alex says:

    I was gonna link the same article (or similar) that Garumoo did, but since I got beat to the punch, I’ll just say this: if you want to see the (awesome) backgrounds and characters in a Rock Band or Guitar Hero game, play on vocals.

  16. Stabs says:

    The holistic value I described only works well if you don’t see the overall scheme. Slipping invisible gorillas in to break up the monotony won’t work on game designers because you understand what’s being done and that it’s a cheap trick. I do think it can work on less sophisticated observers.

  17. Eric says:

    @Stabs: It’s true that getting murdered for no good reason can be a memorable story. But it seems pretty arbitrary to assert that this is a crucial tool in the MMO toolbox. It’s just a trivial-to-implement one, but I don’t see anything that suggests it’s a unique or distinctive one. Which brings me to my major point, that designers don’t consider the psychological ramifications of this decision, which is to subtly increase the frustration factor of their game in ways beyond the shock-and-awe factor that they intended.

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  19. Garumoo says:

    @sandra the bit that really caught my attention was the example exercise:

    >> “I gave both lucky and unlucky people a newspaper, and asked them to look through it and tell me how many photographs were inside. On average, the unlucky people took about two minutes to count the photographs, whereas the lucky people took just seconds. Why? Because the second page of the newspaper contained the message: “Stop counting. There are 43 photographs in this newspaper.” This message took up half of the page and was written in type that was more than 2in high. It was staring everyone straight in the face, but the unlucky people tended to miss it and the lucky people tended to spot it.”

    The similarity is with counting the number of ball passes by the white team and completely missing the guy in a gorilla suit. Similarly with the experiment of focusing on the centre dot and then showing big dots on the edge of the screen.

    The “unlucky” people had a habit of hyper-focusing on their current goal (ball passes, counting photos, the centre dot, etc), and being blind to everything else.

    >> “For fun, I placed a second large message halfway through the newspaper: “Stop counting. Tell the experimenter you have seen this and win £250.” Again, the unlucky people missed the opportunity because they were still too busy looking for photographs.”

    Further underlining the effect of selective attention was the experiment that ratcheted up the anxiety level:

    >> “In one experiment, people were asked to watch a moving dot in the centre of a computer screen. Without warning, large dots would occasionally be flashed at the edges of the screen. Nearly all participants noticed these large dots.”
    >> “The experiment was then repeated with a second group of people, who were offered a large financial reward for accurately watching the centre dot, creating more anxiety. They became focused on the centre dot and more than a third of them missed the large dots when they appeared on the screen. The harder they looked, the less they saw.”

    The thing is though, whether a subject did or did not see the other thing wasn’t some purely random thing, independent of the subject, but instead was highly correlated with that person. That is, some people were repeatedly blind to the non-focus things (whether they be threats or opportunities), while others were more perceptive and did in fact notice them.

    What is especially interesting in that article was that you could learn skills that shifted you from the “unlucky” camp to the “lucky” camp. That is, you _could_ learn to be more perceptive… with the right program and reward system etc. With those skills, you won’t get ganked by invisible gorillas – you’ll see them and adjust accordingly.

    The frightening thing is that maybe certain games are (inadvertently) teaching the opposite lesson.

  20. They mention having cues such as the rumbling ground and such but these type of things happen when you’re already engaged in a distracting task. I think the solution is internal consistency and cues happening a greater time before the event itself. Finding giant sized foot-prints or flattened enemies before you get into the fight might make you more likely to cue in on the possibility of a giant nearby.

    In the newspaper example if one of the photographs was of a sign that said something about an unrelated “if you read this…” I wonder if more people would pick up on the later 2nd page or monetary reward message.

  21. Garumoo: I wonder if that is getting at the “invisible gorilla” effect (noticing your surroundings when your brain is focused), or just making you more aware of your surroundings when you aren’t otherwise engaged. There’s a long tradition of being able to improve your awareness in general — for instance, the martial arts have various exercises intended to help train you to always be aware of potential dangers. The martial-arts exercises work great for me when I am first entering a room full of people; they are a whole lot harder to put into practice while I am trying to study in a crowded library.

    The people who spotted the giant sign in the paper didn’t count the numbers at all (otherwise they wouldn’t have taken just two seconds to complete the task). If they had been forced to actually begin the task before a giant clue came up, would they still have noticed it?

    In other words, the interesting question to me is: does this help you notice things when you’re actively engaged in something, or just train you to notice surroundings before engaging in a deep task? If the latter, that is probably pretty useful in real life, but much less so in video games.

  22. Thomas Lindgren says:

    This might be a holdover from some single-player games, where as part of the challenge you often have to learn an obstacle course with numerous distractions and/or tasks to juggle. Part of the game contract is that you will fail in this a few times. But as far as I can tell, you do learn.

    Luckiness by reading the text: what if there actually were 44 pictures? Your lazy shortcut and lack of attention now means you failed in your task. The nazis kill your family, the vaccine against rotting malaria is lost, you’re drummed out of the Science Corps, and you don’t get that promotion.

    (Pet peeve: I get the impression that a lot of these currently popular lab tasks that demonstrate our supposed lack of sense are played in such ways that the incentives are all wrong. Would paying attention to gorillas while being tasked to count dots have been seen as the raw material for an alternative article concerning a deplorable lack of focus? But perhaps this turns up equally or more in economics. “We will now play a game. The professor here splits the funds in two parts, whatever way he chooses, one part for him, one part for the doctor, while the doctor gets to either accept or reject the deal. If the deal is rejected, neither one gets anything. Think it over, professor. (Time passes.) And the split of funds proposed by you, Professor, is … that you get $100, while you, Doctor, get one grey pubic hair of unknown provenance. What’s that, Doctor, you refuse? Even though you are better off by one pubic hair than previously? This conclusively proves humans are irrational!”) (Okay, I feel better now.)

  23. Robert yang says:

    Isn’t the solution to the death-trap monster thing obvious? Make the death-trap interact with whatever the player’s occupied with: have the gorilla swipe at the ball.

    If you’re farming mobs and there’s a giant dragon nearby, have the mobs start screaming / point at the dragon / run away.

    Or am I oversimplifying here?

  24. Pai says:

    @Robert: I think that’d be an awesome idea. RPGs are supposed to be about immersion in a world, and to make NPCs and even other mobs react in realistic ways to each other would enhance the overall experience, imo.

  25. Stabs says:

    Eric, if invisible gorillas were the only variation in a sea of kill ten rats quests then I’d agree with you. However what makes playing WoW more immersive, more sticky for players is the hugely diverse variation. Invisible gorillas are a tiny part of a greater whole. What I’m praising is the mosaic of varying game experiences.

    WoW’s different from other MMOs in that most other MMOs have an overall theme and try to stick with it whereas WoW is designed on the “ok, we’ll stick that in somewhere” philosophy. WoW is sticky because there’s tons to see and do and veterans find a routine without finding a rut.

    When you say “designers don’t consider the psychological ramifications of this decision” I’m sure you’re wrong. I can point you to comments by Max Schaeffer about Diablo 2 in 2000 that showed that Blizzard valued frustrating and unpleasant mechanics as a way of varying the play experience: “the feeling of tension and fear that makes the rewards of success that much better”.

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  28. Michael Wright says:

    I agree with Robert Yang. This research should serve to point out to developers the need to be aware of and manage the player’s focus. If the ball in the original example turned red everyone would notice it. If they were told beforehand that a gorilla might cross the screen, how many people would miss it? If they did miss it, they would be much less likely to feel tricked. They were told to watch the ball and that’s what they did. I would be upset if I was in one of these experiments and I “failed” because I did exactly what I was told to do and that wasn’t really what they wanted after all.

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  30. Dr. Shiva says:

    Another much simpler trap of this type many people will stumble in is the one with the bus riddle. Tell them a specific number on passenger in the bus and at every stop you modify the numbers of passenger who enter the bus and leaving it. Makes this several times and then ask them how many time the bus did stopped! You will be surprised that most people who do not know the trick will fail to respond clearly! Even this shows quite well, that humans can only focus on one thing well. The result of this you can see daily everywhere for example in accidents on which you have to think how was this possible at all like a car who is colliding with a big truck or with a tramway. How can it be that the drivers are overseeing such big vechicles? The answer ist that humans can only have one primary focus. And if that one is demanding then all other stuff is getting locked out completely!

  31. ZZTRaider says:

    It’d be really awesome if someone did a similar study comparing the people that enjoy playing on PvP servers (preferably one with a good bit of PvP actually going on) and the people who notice the gorilla, to see if there’s any correlation.

    Personally, being on a PvP server meant that even during combat, I would constantly be turning my camera, watching my surroundings to ensure that nobody sneaks in behind me to gank me. Even while chatting with guildmates in Ventrilo, it was never a big deal, because staying aware became part of the routine, out of necessity. After all, for the vast majority of enemies that you’re fighting while leveling or farming, it’s not all that important to be as efficient as possible.

  32. Dr. Shiva says:

    Here the enhanced version of the gorilla movie:

  33. Todd Berkebile says:

    Sounds like a good book to add to my reading list. I wonder if film directors would have good insight into this selective attention phenomenon that might be adapted to video games. In film its very important to control and direct the viewer’s attention so they are looking at the right places at the right time.