Does practicing in your head work? What three reviews of mental practice found

The pool is closed until Thursday

Say you signed up for adult swim lessons the month you turned 55. Class meets twice a week. In between, the pool is crowded or too far away.

You can get from one end to the other. What you cannot do yet is breathe to the side without lifting your whole head, which sinks your legs.

On the off days you watch a video of the stroke and nod along. By Thursday most of it is gone. The instructor says "roll, don't lift," you know exactly what she means, and your body does the old thing anyway.

You may have more practice time than you think. Some of it can happen on the couch or in bed. It will not replace the pool, and the research is plain about that. But those minutes are worth something.

Rehearsing the move, not picturing the trophy

There is a lot of fuzzy talk about visualization: see yourself winning, hear the crowd. That is not what this research tested.

In the studies, mental practice has a narrow meaning. Driskell, Copper and Moran, in a 1994 review, defined it as "the cognitive rehearsal of a task in the absence of overt physical movement." In plain words, you run the movement in your head without doing it.

For a swimmer, that means the arm reaching forward, the body rolling and one goggle staying in the water while the mouth clears. It does not mean a picture of yourself as a confident swimmer at the beach.

That review pooled the earlier studies. It found that "mental practice has a positive and significant effect on performance." The size depended on the kind of task, the gap before testing and how long the mental practice lasted.

How big the effect is once the bias is checked

The 1994 review is three decades old, and much of psychology has been rechecked since. So in 2020, Toth and colleagues ran a follow-up of 37 studies published between 1995 and 2018.

The effect held up, but it shrank. After checking for publication bias, they wrote that mental practice "has a small but significant positive effect on performance." The number was r = 0.131. Task type and the kind of imagery changed the result.

A 2021 meta-analysis by Simonsmeier and colleagues looked at imagery training in sports. It found an overall effect "medium in magnitude," with d = 0.431. Imagery helped performance, and also motivation and how people felt. More intensive training tended to work better.

Three reviews across 27 years point the same way. Mental practice helps, and its honest size sits between small and medium.

Then comes the part most visualization advice skips. A 2022 meta-analysis by Jiménez Díaz and colleagues pooled 24 studies and compared three kinds of practice. During learning, physical practice alone had an effect of 1.75. Mental practice alone came in at 0.80, and the two combined at 1.78. In their words, mental practice "does not replace" physical practice, but it can add to it "under some conditions."

The book adds one fair caveat. In some studies the combined group may simply have practiced longer in total. The safe reading is that adding a few imagined reps to real practice helped more than real practice alone, in the studies we have.

One more finding matters. A 2021 review by Ladda and colleagues listed past experience with the movement among the factors that shape results. Imagery seems to work better once you have done the move for real.

Add imagined reps around the real ones

The Practice Lab gives this research two drills in Practice in Your Head, and both are SOLID.

The Mental Run-Through takes five to ten minutes:

1. Pick one short piece of the skill, a few seconds long, that you have done for real a few times.
2. Sit or lie still, close your eyes and run it at its real speed.
3. Include how it feels: where your weight goes, the sound, the water.
4. If the imagined version goes wrong, stop, rewind and run the correct one.
5. Do five to ten runs. Stop early if your mind drifts.
6. Write one detail you had not noticed before.

Mix Real and Imagined Reps adds three to five minutes to a normal session. Do three imagined reps before your first real rep of a hard piece, and two between sets. On days you cannot practice for real, do a Mental Run-Through instead. Never trade a session you could do for an imagined one. If you are resting an injury, ask your doctor or physical therapist before adding any reps. The book says the counts are a starting point, since no study settles the best ratio.

The chapter Watch, Copy, Get Coached adds one link. A 2022 pair of analyses by Chye and colleagues found that watching a model while imagining yourself doing the move beat watching alone. It did not beat imagery alone.

We find the honesty here useful. The drills earn their SOLID badge, and the effect is still modest. That is the right size of promise for a skill you are building on a couch.

If your bigger problem is when you practice, see how long a practice session should be.