Daniel J. Simons is a professor of psychology at the University of Illinois where he heads the Visual Cognition Laboratory. In addition to his position in the Department of Psychology, he is affiliated with the Center for Social and Behavioral Science and has a courtesy appointment in the Charles H. Sandage Department of Advertising. His research explores the limits of awareness and memory, the reasons why we often are unaware of those limits, and the implications of such limits for our personal and professional lives. He is a Fellow and Charter Member of the Association for Psychological Science, a fellow of the Psychonomic Society, an Alfred P. Sloan Fellow, and he has received many awards for his research and teaching, including the 2003 Early Career Award from the American Psychological Association. He was the founding editor in chief of the APS journal, Advances in Methods and Practices in Psychological Science. He is the co-author, with Christopher Chabris, of the 2023 book Nobody’s Fool as well as the 2010 New York Times bestseller, The Invisible Gorilla: How Our Intuitions Deceive Us. He has published more than 100 scholarly papers and has penned articles for the New York Times, the Wall Street Journal, the Chicago Tribune, Smithsonian Magazine, and the Chronicle of Higher Education, and many other outlets.
Zan Boag: Interestingly, my daughter has been studying your gorilla experiment at college over the last month. I’ve showed it to several people as well, and it’s incredible just how many people miss what is directly in front of them.
Daniel Simons: I think that’s why it went viral – about half the people miss it. You can have two people in the same room experience it differently. It’s like the dress illusion or the rotating dancer illusion where people can’t understand how someone else sees it differently. That sort of thing has a way of going viral. It went viral before YouTube.
It is mentioned alongside Milgram’s and Mischel’s experiments as something that has reshaped the way we think about human nature. What were you setting out to achieve with this? What did you want people to confront?
We had no grand aspirations for it at all. Chris Chabris and I were actually replicating and extending much earlier work of one my mentors, and one the founding figures in cognitive psychology, Ulric Neisser. He had done the original work in the 1970s – I don’t know if you know his work, but he had videos with people passing basketballs and a person wearing a coat and holding an umbrella walked through, and other variants as well. People didn’t notice. We were replicating that.
His studies were after a different question – he was interested in whether attention is focused on objects or regions of space. A common view at the time was that attention worked like a spotlight, that wherever you direct the light, that’s what you become aware of. And Neisser was of the view that, no, attention locks onto objects, not to regions of space.
So if you’re paying attention to one object and another object passes through literally the same space, you might not see it because your attention is locked onto a different object, not that region. His videos looked ghostly. All the players were partially transparent and both teams were overlapping – they literally occupied the same physical space. And the person walking through also did.
So, he found the same thing way before we did: people didn’t notice the unexpected person going through the scene. People knew about his studies. The umbrella woman was in textbooks. But it was ahead of its time and didn’t have quite as big an influence on the field as it should have. People said, “yeah, there’s that result, but whatever, we’re going to study our letters flashed on computer displays”. I think part of the reason for that was that it was a weird looking display – these partially transparent black and white players moving through the scene. It was three different films, superimposed, using mirrors, filming off the mirrors. It looked grainy and weird. If you look closely at the video, you’ll see Ulric Neisser is in it on both teams. We heard people say, yes, I know that effect, but I think it’s just something weird about the video. So part of our goal was to replicate it with better technology and make it look vivid. And then to run a version where, if Neisser was right, you should be able to miss things that were fully visible, that were not partially transparent, not overlapping like he had, but just right there in front of you. That’s where our variants came in – the gorilla variant was intended to make it as obvious as we could.
I don’t think you could have made it any more obvious. I still find it incredible that we’re able to miss this. It does pose the question: if we can miss something this obvious, how can we trust our perceptions?
Well, I think one of the things that’s interesting is our metacognitive belief that of course we would see this thing. And I think that’s the big error we make; not that we miss things. Because at some level, of course we miss things. But focusing attention, that’s something we have to do really well. And the things you’re focusing on, you do tend to notice – you tend to process those in a lot of detail and to become aware of them.
We’re really good at observation of the thing we’re trying to direct our attention to. But when it’s something unexpected, most of the time we don’t care about that, and most of the time we don’t want to be aware of it. If we were constantly aware of everything in our surroundings, given the limitations we have on how much we can process, we’d never be able to do anything. We’d be perpetually distracted by irrelevant stuff all the time.
So that ability to select and focus is really an essential ability. It’s just that every now and then there’s something that we actually would want to see that gets filtered out. And that’s where the phenomenon has practical ramifications. What’s most interesting to me is why we have this metacognitive belief that, as you say, it’s hard to believe anybody could miss it. And if you miss it, “How could I possibly miss that?” is a strong belief that if there’s something really important, it will grab your attention. That’s wrong. And that’s an interesting metacognitive error that has all sorts of consequences.
You took it a step further – well, when we’re forewarned about the gorilla, It’s very easy to spot it because we can focus on it. But you created the “monkey business illusion” to test whether forewarned viewers would still miss key events. There are limits to being forewarned as well, aren’t there?
I think to some degree, yes. If you know about the gorilla video and I ask you to count people passing basketballs, you’re going to be looking for a gorilla. And that’s partly I did that follow-up – so many people, at least undergraduates on a college campus, already knew about the gorilla experiment because they had seen it in their classes or in high school. So I wanted to see, OK, what happens if they’re looking for that gorilla – they know it’s going to be there because the video looks somewhat similar and I’ve asked them to count passes. If they know what I’m up to, and they know I’m going to show unexpected things, are they then protected? Do they then notice other unexpected things? And the reality is no, they don’t automatically notice other unexpected stuff. The do notice the gorilla. But if anything, there’s a very small trend toward them noticing less of the other stuff.
I think that makes sense, because if you think about just how much information there potentially is in the world to pay attention to, even in a simplified video like that, there’s a lot of things you could pay attention to. There’s a huge number of things I could change or I could do, and we just can’t take in everything. So you take in what you’re looking for. You take in what you’re trying to do.
It makes me think that contemporary society has presented us with such a huge range of distractions. When life was a little bit simpler, we didn’t have so many distractions, we still had issues when it came to observation as there are limits to what we’re able to observe. But with all the distractions in the modern world, how do we focus on the things that are important to us when we have so many demands on our attention?
Those distractions increase your chances of missing things that you’d care about. My colleague Ira Hyman at Western Washington has done a number of studies, a lot of them observational, where he’ll do something in the middle of a college campus or on a sidewalk, and look at whether or not people notice it. So he’ll ride around on a unicycle in a clown suit on the centre of the college campus, or he’ll place a placard right in front of people on the sidewalk that they’re walking down, or he’ll hang money from a tree as they walk by it.
And what he looks at is whether or not people notice it when they’re alone or when they’re talking on their phone or when they’re walking with someone else. And talking on a phone dramatically reduces your chances of seeing these things, of observing them. So I think you’re right, that there are more opportunities to use up whatever limited resources we have to notice what’s around us.
What’s interesting is that you can get by. You can walk right past that sign, not see it, but avoid tripping over it. Just like you can drive home without necessarily remembering every turn or stop sign. You probably didn’t violate too many rules of the road. Because we can do a lot without really paying a ton of attention. But to become consciously aware of what we’re doing and to retain it, we really have to focus on it. And the more you use up that focus, the less you’re going to notice. So, yes, I think that the complexity of modern society can be an issue.
You talk about conscious awareness as something that is extremely important to us, but by the same token we do need to get through life, we need to set that aside sometimes. Otherwise, as you say before, it would be too much for us, too much stimulation. Do you think potentially that we’re developing ways to deal with this, to block out certain things, or is it something that is already a fundamental part of being human?
I think it’s fundamentally part of being human, especially for action. Navigation, avoiding obstacles, that’s all stuff that we just do automatically.
In the same way that when you first learn to drive, you have to think about how hard to press on the accelerator pedal to know how much you’re going to accelerate. You have to think about how hard to turn the wheel. And all of that stuff eventually becomes automated. I think a lot of things can become proceduralised like that. They can become automatic, so you don’t have to think about how far to step to avoid that rock while you’re walking. You just do it.
But I think there are limits to what can do that for. You’re not going to be able to automate counting how many times people pass a ball. You’re not going to be able to automate making a decision about whether or not to merge in traffic. You automate the process of doing it, or aspects of the process of doing it, but you’re not going to be able to automate that decision, the conscious decision. You might be able to automate maintaining a distance behind the car in front of you without thinking about it, but making a decision to act is different. I don’t think you’re going to be able to automate having a conversation on a phone in a way that would not interfere with your driving. So, yes, I think there are limits.
Well, this brings me to multitasking, which you say is a myth. But as you say, modern life does cause people to engage in these high-risk habits, like speaking on the phone while they’re driving. Do you think there are issues in the way that we have to operate in contemporary culture with the way our minds actually work?
One thing I should say, I think people misuse the term multitasking. People will tell you, “Oh yeah, I’m always multitasking at work.” What they’re really doing is sequential tasking. The switch from one task to another to another back and forth. They’re generally not doing two things simultaneously very often.
The notion of multitasking in cognitive psychology is actively doing two things at once that in principle could rely on the same resources. So talking and driving both, it turns out, use some shared cognitive attention mechanisms that interfere with each other, just like chewing gum and whistling use your mouth parts in conflicting ways. So we can’t really do those things simultaneously. But there is a cost for switching a lot. When you’re doing one task and you have to switch to another task, that incurs a cost every time you do it. And there’s no real way around that.
So yes, I think the ability to devote yourself to focusing on what you need to focus on is a real challenge. And it requires a lot of willpower. It requires you to not have your phone active when you’re trying to drive. But you can take those steps to protect that focus. You can turn your phone off while you’re driving, if you really want to avoid the consequences of it.
This makes me think of a meeting I was in the other day. During the meeting, somebody asked me to send them a file. I was only away from the conversation for 30 seconds; I sent the message and then came back to the conversation. But I had no idea where we were anymore. Only 30 seconds had gone past, they’d hardly discussed anything, but I found it very difficult to get back to the conversation, it took me several minutes to get back on track.
It can happen with even a shorter gap, there’s a cost, there’s a slowdown, there’s an effort to switch back and forth to a different task. Every time you switch from reading an article to checking your email, getting back into the article takes more time than it would have if you had just kept reading.
I think for things like inattentional blindness, it’s hard to imagine that evolutionarily it hurt us much because if it was such a limitation that it put us at risk all the time, we probably wouldn’t have survived. I like to think of it as a by-product of things we do really well, which is focusing attention. Modern society puts us in situations where our ability to focus attention means that we could potentially miss a lot more things that are a lot more consequential. We didn’t evolve to travel at 100 kilometres an hour. Our visual system isn’t that quick. We can do it, but it’s not trivial. And that means if you miss something for a second or two, that’s the difference between missing an accident and having a fatal one. So the consequences are bigger of failed observation now than perhaps they were before.
One of the things that stands out for me in your research is that we’re only aware of the things that we notice; we don’t have a full sense of what’s going on. Is it similar to Plato’s Cave, we’re only aware of the shadows on the wall, only what is presented to us?
I wouldn’t necessarily go that far because that almost implies that we’re not seeing reality. And I actually come from a Gibsonian perspective on perception. I don’t know how much you’re familiar with that worldview, that we basically evolved to perceive the information we need from the world. The Plato’s cave example implies that we’re seeing only a shadow of reality, but I think we largely do see the world as it is. Or, at least, we can get the information need from the world really effectively.
For the most part, what we focus on, we actually do see. And we can make sense of it really effectively, we can navigate in the world, which requires perceiving the world as it really is. If we were perceiving only shadows on a wall, we’d trip over things a lot more than we do. We actually are perceiving the three-dimensional structure of the world as we navigate through it. So really, I think observation is quite good; it’s just that it’s limited – we can’t take in everything.
I think the bigger issue with inattentional blindness is less about failures of observation. It’s more about that failure of metacognition, that we believe we’re observing everything and that we’ll notice everything when we’re mostly aware of only the things that we’re focusing on. We believe that we have this rich representation of everything around us, and the reality is we probably aren’t really taking in as much from anything other than what we’re focusing attention on. We get some detail, we get some information, but not the kind that leads to rich and detailed awareness.
Another part I find quite interesting is that observation does, in a way, relate to our memory and memory’s constructive nature. It means that our life stories feel vivid, and it feels like we know what happened, but the details are, well they may be incorrect, but they’re also going to be different from the details people have who are within in the same situation. Given this, how do we make sense of our memories and how we observe our own past? Can we rely on our memories or is it something that we should trust only to a certain extent?
I think we should trust it only to a certain extent – we can have a really vivid memory of what we experienced but be completely wrong. I’ve had this experience. One of the things Chris Chabris and did when we were writing our first book was that we recalled what we were doing when we heard about the attacks on September 11th. So I wrote out a detailed description of what I was doing, where I was, who I was with. I remember being in my lab with my three graduate students who were all named Steve, which made it memorable. And I went through the entire course of the day, wrote out about a page or a page and a half.
I then emailed all three Steves and asked them to do the same thing without talking to each other and without me telling them anything about what I remembered. And it turns out that only one of the three was there. The other ones had pretty good evidence that they weren’t there. One was giving a talk on the other side of campus and one was asleep, which was in character.
I didn’t remember the postdoc who was in my office at the time we heard about it. I didn’t remember him being there. And I’m sure he was because he and the other Steve who was there remembered him being there and had lots of details about that. But I didn’t remember him there. It wasn’t part of my memory even though I thought I remembered that day pretty vividly. I’m sure there was a lot of information that I was aware of at the time. I presumably knew he was in my office when we were meeting and talking to each other. It didn’t stick.
And how long after 9/11 was this?
It was about seven, eight years after. I imagine the next day I would have remembered it very well, but I didn’t actually do that recall test for years. And when I did it, it was way off.
I think that’s one of the reasons we develop these mistaken intuitions. And they’re not just about perception, but they’re about memory too. How often have you tried that? I recall something really vividly. It feels like I’m playing it back to myself on a recording. But how often do you then check the other evidence at the time to see if you’re right? Most of us never do. And the only times that comes up are when you have a dispute with your spouse or a sibling about what happened when. So the end result is we think we’re right and we think they’re wrong and that leads to conflict.
The only groups who have that check on their memory regularly are politicians. When they recall something about their youth, they’re telling their personal narrative and somebody actually looks into it and finds that they are wrong. And then they’re accused of being a liar when they might just have misremembered it. It’s like the fishing story where the fish you caught gets bigger and bigger every time you recall it.
Another group are people who work on film sets trying to catch errors. I’ve interviewed a few of them and what they tell you is, “I maybe have a slightly better visual memory than most people”, but the more important thing is that they have good metacognition. They know they can’t trust what they recall with absolute certainty. They say things like, I could have sworn to you that their life jacket was on over their right arm. But then I checked and it wasn’t. They get that experience of being wrong often enough that they correct themselves and recognise they can’t trust a memory just because it seems vivid.
So what do you think is at play here? Why is it that we have memories that we can’t trust?
Well, I mean, I think that’s just not how memory works. We don’t form this perfect recording of everything we’ve experienced. If perception is limited, we’re focusing on some things and not others, and we take in information to make sense of the world, which is really the goal here. Our goal is to make sense of what’s around us. And that making sense process applies both to vision and to memory. When you recall something, you recall the gist of it, the core of it, you might recall some details, but what you really recall is how you made sense of it. And that can change over time as your sense of the world changes.
So I tend to think of memory more like improvisational jazz where the theme may be consistent, but the performance every time is different, unlike a recording on a CD or something. It’s not repeating the same thing every time you recall it, so it can get distorted over time. Most of the core elements of it are likely to stick around, but details can drop out; details might be incorporated that you never remembered. But again, people are convinced that they’re right.
I wonder if photographing and videotaping everything is leading to an increase in our ability to form more solid memories. Now, I can go back to a video of a family event, or so, and I’ll remember in clear detail because I have this crutch.
The interesting question is whether you are remembering the event, then, or whether you’re remembering the representation of the event, the video or the photograph. It means that you can start getting source memory failures – things that you remembered only from the video, you’ll really feel like you remember them happening to you, but if I hadn’t shown you the video, you’d have no memory of them happening to you. Elizabeth Loftus and others have studied false memory that way, where they bring people in and give them photographs that have been altered to show them doing something they hadn’t actually done. And with enough prompting, at least some of the time they begin to mis-remember having done it. You lose track of what really happened to you and what you imagined happening to you.
You can also get transfers of memory – somebody tells you the story of their experience and you incorporate it into your own life. Chris and I wrote about a fun example of this where we have a friend who studies memory. I won’t name names. He was telling this amazing story about how he met Patrick Stewart, the actor, at a restaurant in Boston. But he hadn’t, he was telling the story to Chris who had actually experienced it and told it to him! He had incorporated it into his own memory.
So I think that one consequence of the possibility of recording everything is that it can be a great reminder. It can help you keep the details right when it was something you experienced, but you can have source memory failures where you incorporate that into your representation of what you had actually noticed at the time and what you remembered. But that said, I trust a video record like that a lot more than my own memory.
A lot of what you’re talking about here is being aware of the limitations of both observation and memory. Clearly in science and in philosophy, finding out deeper truths or diving into a topic begins with doubt. Do you think part of what you’re trying to achieve with your experiments is to make sure that we’re aware of the limits of our intuitions and memory, of our observational skills?
I think that’s the only thing we can really fix; we’re not going to be able to dramatically change the capacity to take in information that’s outside of our focus. That’s probably a hardwired structural limitation we have. We might be able to accentuate it using video and other sorts of tools so that we have more information available later, but we’re probably not going to fundamentally change our capacity to focus attention in the same way that we’re not fundamentally going to start being able to see ultraviolet light.
We’re just not built that way. We can change the intuitions. Those script editors on movie sets who are finding all of these continuity mistakes, the lifejacket that’s no longer there. They learn when to trust their memory and when not to trust their memory. They learn to pay attention to the things that people are likely to pay attention to. So you can overcome that intuition – you can take the steps to recognise that, yes, I’m probably not going to be aware of this, I’m not going to be noticing everything. So I should maybe focus on my driving and put down the cell phone.
I think the reason why we have those mistakes is straightforward. If you miss the gorilla and I never asked you about a gorilla, you’re going to go through life convinced that of course you would notice a person in a gorilla suit, even though you didn’t. Because you’re only aware of the things that you happened to notice. I’ve had people come into the lab and tell me, “Oh, yeah, I always notice mistakes in movies.” And I know they don’t because I showed them a one-minute video with 10 mistakes in it, and they didn’t see any of them. The metacognition is really hard to overcome until it’s thrown in your face. And I think the gorilla video did that, which is why it went viral. We didn’t’ expect it to go viral like that, though. I mean, if I had expected that to go viral, we would have filmed it in much better quality.
Given the research that you’ve done, do you have any advice for readers who want to be more observant – not to see everything, but just to be a bit more aware of what’s going around them so that they can get more out of their lives?
Focus on the things you actually want to see. And try to anticipate when there are going to be risks if you miss something. You’re never going to be able to take in everything. And when people ask me that, hey, what can I do to always see the gorilla? I’m like, no, you wouldn’t want to. That’d be horrible. That would be a terrible existence. You’d never be able to focus on anything. You’d be perpetually distracted by every leaf blowing down from a tree. You wouldn’t be able to walk to the park. So I don’t think that’s the solution. I think the solution is to think about times when the limitations on our observation are going to matter.
If I have you just watch that video and don’t count passes, you’ll likely see the gorilla because it’s kind of obvious. So if your goal is to take in the obvious stuff, the less you’re engaged in doing something else, the better off you are. But the same applies when you’re doing something that does require a lot of attention. Recognising that that means you don’t have those resources available and you’re not going to spot all the extra things that you might care about.
So you need to be observant up to a certain point, but being too observant would come at too great a cost. And this is clear – there are some people who are distracted by everything. They walk down the street and they see every person’s face; they notice every detail of what people are wearing. Is it a matter of being able to move between the two states, being able to observe and be able to focus on some things, but not so much so that you’re not able to operate effectively?
It’s an interesting question. Is there a sense in which we’re always observant to the same extent? It’s maybe a question of how focused we are. So you can zero in on, I’m really paying attention to this page of text right in front of me. And that means I’m not paying attention to anything else in the room if I’m zoomed in on that, but I’m really observant, hyper-observant of that. But if I’m not focused on that text, I might see a lot of other things.
I don’t know if it’s really that the amount we’re observing is fluctuating all that much. It’s more a question of how focused we are on doing something. So when we’re not focused on doing one task, if our goal is to scan around us and see how much is going on and look at things in as many different ways as we can, we can take in a lot. But that means we’re not really focusing intently on any of them and we won’t get the details. We’re just focusing that attention more broadly. I think that’s useful.
The other context in which it’s really useful is if you know that you have to focus, but you might really need to see other things that you weren’t looking for. That’s a time to have multiple people looking. If you’re a radiologist and you’re scanning radiographs for one particular problem, but you would want to notice if there were other unexpected problems. You either have to stop and do it again, not looking for just that one thing, but with a mindset of, “is there anything else in this image that I should be worried about?” And it’s a deliberate choice to do that, or have somebody else do it. And that compensates for it, because you’re focusing – you’re both being really observant, but of different things in different ways with different goals.
From the Observation edition, available from our online store
