GUIDE · ACT

Leaves on a stream: how to watch a thought float past without chasing it

A thought like "I'm going to mess this up" shows up, and it lands like a fact. Leaves on a stream is a short exercise from Acceptance and Commitment Therapy (ACT) for practicing a different move: you watch the thought drift by, the way you'd watch a leaf on moving water, and you stay where you are while it goes. This page has a full script you can follow alone, fixes for common snags, and a plain account of what's been tested.

What it is and where it comes from

Leaves on a stream is a guided visualization. You picture yourself on the bank of a slow stream, put each thought that arrives on a leaf, and watch the leaf float out of sight.

It's an ACT exercise. Steven Hayes and colleagues laid out ACT in a 1999 treatment manual, and its model includes six processes, with defusion one of them. Russ Harris's summary of defusion techniques from his ACT textbook lists this exercise among the classics.

Many versions of the script circulate, including a 20-minute recording used in one study. We couldn't trace it to one original author, so we won't credit one. The script below is our own wording.

The script: about seven minutes

Read the steps once to get the shape, then do them with your eyes closed, or record yourself reading them slowly and play it back. Set a timer for five to ten minutes.

1. Settle in. Sit with your feet on the floor and close your eyes, or lower your gaze a few feet ahead. Take a slow breath.
2. Find the stream. You're sitting on the bank of a slow stream. Add whatever details come easily: the sound of the water, the stones below, light through trees. Leaves float on the surface at their own pace, and for a minute you just watch them from the bank.
3. Let a thought arrive. Sooner or later your mind will produce something: a worry, a memory, a plan, a comment about this exercise. Notice it and name it in a few words, like "I'll be late" or "my chest feels tight."
4. Put it on a leaf. Set the thought on a leaf, the way you'd set down a note, and let the leaf go. Watch it float until it's out of sight, however long that takes. A painful thought and a boring one get the same treatment.
5. Repeat without hurrying. Do this with each thought that comes. Sometimes thoughts arrive in a crowd, and sometimes the water stays empty for a while. If it's empty, watch the empty water. You don't need to produce thoughts or stop them.
6. If a leaf snags. If a leaf catches on a rock, watch it catch and notice what your body does. It may come loose in seconds or stay a while. Let it, and move on to the next.
7. If you get pulled off the bank. At some point you'll realize you've been inside a thought for a while, replaying a conversation or making a plan. Nothing went wrong: you noticed. Say "I drifted," put that on a leaf, and step back onto the bank.
8. Keep going until the timer. Stay with it for five to ten minutes in all. Thoughts about how long it's been, or whether you're doing it right, go on leaves too.
9. Come back to the room. When the timer sounds, let the stream fade. Notice your breathing and the chair under you. Wiggle your fingers and open your eyes, then take a moment before you stand.

Afterward, jot down one line about what showed up most. You can practice on a schedule or in the moment when a thought has a grip on you. Try it for a couple of weeks, then judge whether it's worth keeping.

What defusion means, and what it leaves out

ACT's word for getting hooked by a thought is fusion. When you're fused with "I'm a failure," the sentence feels like a fact about the world, or like an order. You see everything through the thought and never see the thought itself.

Defusion means noticing a thought as a thought: words your mind produced, passing through. The method leaves the thought alone and changes where you stand when you look at it. The thought can stay unpleasant and come back tomorrow. What shifts is how much of your behavior it runs. Our guide to cognitive defusion goes deeper.

Defusion gets mixed up with three other things. Distraction turns your attention elsewhere so the thought fades, while here you keep watching your thoughts from a little farther back. Suppression pushes a thought out of your head. In a 1987 lab study, people told to avoid thinking about a white bear couldn't, and afterward they thought about it more than people asked to think about it from the start. Positive thinking swaps in a nicer thought. Nothing gets swapped here: "I'm going to fail" goes on a leaf the same way "I'll be fine" does.

What's been tested, and what hasn't

Lab studies of defusion in general look encouraging. In a 2004 series of eight single-case experiments, rapidly repeating a single word from a distressing thought made the thought less believable and less uncomfortable than a distraction task or a thought-control task did. A 2012 meta-analysis of 66 lab studies found positive effects for defusion against inactive comparison conditions. A five-day study in 2016 found that defusion lowered the believability of one negative thought more than cognitive restructuring or no strategy did.

The limits are real. These were short lab tasks, and the 2004 study tested word repetition, not a stream, so it says little about this exercise.

The only controlled test of this exact exercise we could find came out flat. In a 2013 study, 57 adults with no mindfulness experience heard either a 20-minute leaves on a stream recording daily for a week or a passage from The Hobbit of the same length. Both groups reported fewer anxious self-statements, and the groups didn't differ. The authors suggested the sample may have been less anxious than a clinical one and a week may be short.

Nobody can promise what it'll do for you, so try it and judge for yourself. We checked the abstracts of the other studies and read the 2013 paper in full.

Problems you'll probably run into

When a thought sticks, keep watching it. Sticking is something thoughts do. Watch for the next thought behind it, or shrink the leaf.

When you get carried off, and you probably will, put "I'm planning dinner" on a leaf and step back onto the bank. Noticing you drifted is the skill you're practicing.

If you feel you're doing it wrong, notice that judgment and keep going. Emptying your mind and feeling calm aren't part of the exercise, and "I'm doing this wrong" is just a thought for a leaf.

If the pictures won't come, a faint sense of a stream is enough, or no picture at all. Say each thought silently and let it go by as a sound, or switch scenes (see below).

If you catch yourself judging the exercise ("this is silly"), that's a thought too. Give it a leaf, then decide afterward whether the practice is worth your time.

If you're bored, boredom is a thought plus a feeling in your body, and both can go on leaves, or you can cut the session to three or four minutes.

If a strong emotion shows up, you don't have to keep going. Open your eyes and press your feet into the floor. A grounding exercise like 5-4-3-2-1 gives your attention somewhere steady to land.

Other scenes

The stream is one picture among several. That summary also mentions thoughts drifting by like clouds in the sky or cars driving past your house. A conveyor belt or a slow train works the same way, since any scene that moves on its own can carry thoughts. If water has a hard association for you, pick one of those.

Illustrative examples: how it might go

These three people are made up. They show how it might go and aren't case studies or evidence of any result.

Dana, 36, a project manager, sits in her car before a presentation and puts "I'm going to freeze" on a leaf. It comes back four times and gets a new leaf each time. She's still nervous walking in, but the thought sounds more like background noise than a forecast.

Marcus, 29, a grad student, sees nothing at the stream and decides he's bad at it. He switches to a conveyor belt and treats each thought as a label on a box, with no detailed picture.

Elena, 44, a teacher, starts with "I let my mother down," and within a minute her throat is tight and she's crying. She opens her eyes and runs through 5-4-3-2-1 with what's in the room. Later she saves that thought for a therapist and practices on a lower-stakes one.

When to stop, and who to ask

This exercise asks you to sit quietly with your own mind, and that doesn't feel good for everybody. A 2020 review of 83 studies of meditation practices found adverse effects in 55 of them, most often anxiety and depression. The authors put the overall prevalence at 8.3 percent and note that these effects can occur in people with no history of mental health problems. The review covered meditation in general, not this exercise.

If the exercise raises your distress and it doesn't settle, stop and open your eyes, then name what you can see. If you have a history of trauma, or your thoughts come with memories that feel like they're happening again, check with a therapist before doing visualization exercises on your own.

Where it fits

Our cognitive defusion guide covers six defusion skills, this one among them. If a loop replays the same scene for hours, how to stop ruminating looks at what keeps it running. Stepping back from a thought usually serves something else, and the values guide helps you name what.

Pick a thought to try it on

The chat below runs with Helpy, the site's AI assistant. Tell it what's been looping in your head, and it can help you pick one thought to put on a leaf.

Evidence and sources

• Masuda et al. (2004), Behaviour Research and Therapy: a series of eight single-case experiments found that rapidly repeating a single word from a distressing thought reduced discomfort and believability more than a distraction task or a thought-control task. Single-case designs and word repetition, not the stream exercise.
• Levin et al. (2012), Behavior Therapy: meta-analysis of 66 lab studies; defusion showed positive effects against inactive comparison conditions. Many defusion methods pooled, and no comparison with other treatments.
• Larsson et al. (2016), Behavior Modification: over five days, defusion lowered the believability of one negative thought more than restructuring or no strategy. Self-report, and we read the abstract only.
• Hartnett & Carr (2013), Journal of Articles in Support of the Null Hypothesis: 57 adults heard a 20-minute leaves on a stream recording daily for a week or a Hobbit reading; both groups improved, with no difference between them. Small, brief, a scale built for the study. The only controlled test of this exact exercise we found.
• Wegner et al. (1987), Journal of Personality and Social Psychology: people asked not to think of a white bear mentioned it more afterward than people asked to think about it from the start. A short lab task with a neutral image.
• Farias et al. (2020), Acta Psychiatrica Scandinavica: 83 studies of meditation practices; adverse events, most often anxiety and depression, appeared in 55 studies, with an overall prevalence of 8.3 percent. Meditation in general, not this exercise.
• Hayes, Strosahl & Wilson, Acceptance and Commitment Therapy, 2nd ed. (Guilford Press): publisher's page for the textbook that lays out ACT's six processes. Not a test of this exercise.
• Harris, defusion techniques summary from ACT Made Simple (2011 handout): lists leaves on a stream among the classics and mentions clouds and cars. A handout, not a study.

Read next

Cognitive defusion (ACT): learning to watch your thoughts from a distanceThe idea behind the exerciseRumination: why your brain runs the same thoughts on a loopWhen thoughts keep replaying5-4-3-2-1 groundingCome back to the here and now through your five senses

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