Selective attention is your brain processing a few things in front of you in detail and letting the rest go by. You can't take in everything at once, so attention picks. What you filter out doesn't feel filtered. It feels like it was never there, which is why you can miss something in plain view.
The best-known demonstration is the gorilla test. People watching a short basketball video are asked to count passes, and many of them never see a person in a gorilla suit walk through the middle of the game. Most explanations stop at "attention is limited." The more useful half is that attention is set. What you're looking for decides what gets through.
The way I describe it comes from snowboarding. I was a professional or semi-professional snowboarder all the way through college. When you're moving fast through the trees, you keep your eyes on the path you want to hit and off the trees you're trying to avoid, because whatever you train your eyes on is where your eyes lead you. Stare at the tree and you ride toward the tree. The gorilla test is the same thing in a lab. Tell people to count passes and they see passes.
A lot of pages say your reticular activating system is doing this filtering. That network mostly sets how awake and alert you are. It doesn't pick out the things that match your goals, and I explain the difference in what the reticular activating system really does. This piece covers the selective attention test itself, why you miss what's in plain view, and a short test you can run on your own week.
What selective attention is
Selective attention is the process of focusing on one stream of information and filtering out the others around it. You do it all day. You follow one conversation in a loud room. You read this sentence and stop hearing the fridge. You look for your keys and walk past the mail on the same table.
It's useful. Without it you couldn't finish a thought. The cost is the one above: what gets dropped leaves no trace that it was dropped.
Divided attention is the other mode, where you try to track two things at once, like driving and talking. Selective attention is choosing one and letting the rest go.
The selective attention test, also called the gorilla test
If you haven't seen it, watch Daniel Simons's selective attention test video once before you read on, because knowing the trick changes the result.
Here's what happens. Two teams of three, one in white shirts and one in black, pass basketballs around while moving. You're asked to count the passes made by the white team. Partway through, a person in a gorilla suit walks into the middle of the players and then walks off.
Daniel Simons and Christopher Chabris published the study in 1999. In their experiment, viewers counting basketball passes often missed a gorilla walking through the game. Across all the versions they ran, 46% of the 192 viewers missed the unexpected event, which was a gorilla in some versions and a woman with an umbrella in others. In the best-known version, the gorilla is on screen for about nine seconds, stops, faces the camera and thumps its chest, and half the viewers in that test missed it. This is one lab study.
The name for this is inattentional blindness: missing something fully visible because your attention was on something else. Psychologists Arien Mack and Irvin Rock named it, and their 1998 book is titled Inattentional Blindness.
Missing the gorilla says nothing about how careful you are. You were told to count passes, and you did the job well. Experts do the same thing. In a later study, 83% of radiologists missed a gorilla drawn into a lung scan, and most of the ones who missed it looked right at it.
Why selective attention misses obvious things
There are two reasons, and most explanations only give the first.
Attention is limited. You can only process so much in detail at once. Counting fast passes takes most of it.
Attention is set. Before you look, you already have a template for what counts. The original study shows it. Viewers tracking the black team saw the black gorilla 58% of the time. Viewers tracking the white team saw it 27% of the time. Same video, same gorilla. The only change was which team they were set on.
Steven Most, Daniel Simons and colleagues then tested this directly. In a 2001 experiment, people noticed an unexpected object more often when it resembled what they were tracking and less often when it resembled what they were told to ignore. This is lab research, one line of experiments. What it shows is narrow: what you're set to look for shapes what you notice.
That's the useful half of selective attention. "Limited" means you'll always miss things. "Set" means you have some say in which things.
Selective attention examples from everyday life
Say you're meeting a friend at a busy station and you know they're wearing a red coat. You'll spot every red coat in the crowd. If they took the coat off on the train, you can walk right past them. Your eyes passed over their face. Your search template was looking for red.
My own example is the trees. When I was riding, the trees were the danger and the gap between them was the goal. Riders and drivers have a name for what happens when you stare at the danger: target fixation. Your eyes go to the thing, and your body follows your eyes. It's a riders' term, not a lab finding, but there is research close to it. In a driving-simulator study, steering drifted toward wherever drivers fixed their gaze. Nobody has run that study on snowboarders, as far as I know.
What I believe about focus, and where the research stops
I believe whatever you focus on shapes your reality, as long as you focus with the right intention. That's my belief, and I'm saying so plainly. Put plainly, focusing on avoiding a problem keeps the problem there, and you keep confirming that reality to yourself. I've walked a lot of people through changing what they look for.
The research backs a narrower piece of that. What you're set to look for changes what you notice, and what you notice is what you act on. It doesn't show that focus moves anything outside you. So I keep the two apart. The gorilla test is the evidence. The belief is mine.
Your week has a pass count
Everyone in that video was given a job: count the white team's passes. Your week gives you a job too, and you usually didn't pick it on purpose. It might be the number in your bank app, the problem at work you keep checking on, or the one thing your partner said on Tuesday.
The hard part is seeing your own count. A reader under one of my Reddit posts put it well: "I feel I am too close to my reality to see it objectively." That's fair. You can't watch your own attention directly. You can write down what you're counting and then check what you missed.
A 3-day test: find your pass count
Five minutes a day for three days. You need a notes app or a page.
Day 1. Name the count. Write the one thing you checked most today. The number, the person, the problem. Then write the question you were asking each time you checked it. That question is your pass count.
Day 2. Name the tree. Write what you're trying to avoid this week. Then write the path you want instead, as something you could see happen: a reply, a finished draft, a calm Sunday. For the rest of the day, when you catch yourself checking the tree, look for one sign of the path instead.
Day 3. Look for the gorilla. Write down three things from the last two days that you didn't notice on Day 1. Something someone offered, a small win, a door that was open. Then look at the problem from Day 1 again. Sometimes what looked like a blocker turns out to be part of the solution.
That's the whole test. Done looks like one page with your count, your tree, your path and three things you'd been filtering out.
This is a noticing exercise. It doesn't diagnose anything. If you think ADHD is part of the picture, a clinician can assess it.
Where to read next
The flip side of missing things is suddenly seeing them everywhere. That's in why something new suddenly seems to be everywhere. The layer under attentional set is expectation, covered in how confirmation bias shapes what you see. If you've ever made a vision board, what a manifestation vision board actually does to your attention applies the same research to it. And the deepest version of the set is your picture of yourself, in how your self-image decides what you notice.
Frequently asked questions
What is the selective attention test?
The selective attention test is a short video made by Daniel Simons and Christopher Chabris. Viewers count how many times the team in white passes a basketball. Partway through, a person in a gorilla suit walks into the middle of the game and walks off. Many viewers never see it. It shows that you can miss something fully visible when your attention is set on a task.
How many people miss the gorilla in the gorilla test?
In the 1999 study, 46% of the 192 viewers analyzed missed the unexpected event across all versions. In the best-known version, where the gorilla stops and thumps its chest for about nine seconds, half of the viewers counting the white team's passes missed it. Viewers tracking the black team noticed the black gorilla about twice as often as viewers tracking the white team.
What is an example of selective attention?
Following one conversation in a loud room is selective attention. So is looking for a friend's red coat in a crowded station and walking past the friend because they took the coat off. Your attention locks onto the feature you're searching for, and things that don't match it pass by without registering, even when they're right in front of you.
Why do we miss obvious things?
Two reasons. Attention is limited, so a demanding task uses most of it. Attention is also set: before you look, you carry a template of what counts, and things that don't fit the template are more likely to go unnoticed. Missing something obvious says little about how careful you are. It mostly reflects what you were looking for at the time.
What is the difference between selective and divided attention?
Selective attention is focusing on one stream of information and filtering out the rest, like reading while the fridge hums. Divided attention is trying to track two or more things at once, like driving while talking. Selective attention picks one thing and lets the rest go. Divided attention tries to keep several going at the same time.
Sources
- Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059–1074. https://doi.org/10.1068/p281059. Lab study.
- Most, S. B., Simons, D. J., Scholl, B. J., Jimenez, R., Clifford, E., & Chabris, C. F. (2001). How not to be seen: The contribution of similarity and selective ignoring to sustained inattentional blindness. Psychological Science, 12(1), 9–17. https://doi.org/10.1111/1467-9280.00303. Lab studies.
- Most, S. B., Scholl, B. J., Clifford, E. R., & Simons, D. J. (2005). What you see is what you set: Sustained inattentional blindness and the capture of awareness. Psychological Review, 112(1), 217–242. https://doi.org/10.1037/0033-295X.112.1.217. Theory and lab studies.
- Mack, A., & Rock, I. (1998). Inattentional blindness. MIT Press. https://doi.org/10.7551/mitpress/3707.001.0001
- Drew, T., Võ, M. L.-H., & Wolfe, J. M. (2013). The invisible gorilla strikes again: Sustained inattentional blindness in expert observers. Psychological Science, 24(9), 1848–1853. https://doi.org/10.1177/0956797613479386
- Readinger, W. O., Chatziastros, A., Cunningham, D. W., Bülthoff, H. H., & Cutting, J. E. (2002). Gaze-eccentricity effects on road position and steering. Journal of Experimental Psychology: Applied, 8(4), 247–258. https://doi.org/10.1037/1076-898X.8.4.247
- Simons, D. Selective attention test (video). https://www.dansimons.com/videos.html
- On the RAS as an arousal network: see the sources in the reticular activating system article.
How this was made: Written by Austin Santos from his own voice memos and notes. AI helped with research and drafting, and every source was checked against the original paper.