Memories of errors made while learning a task for the first time can help you learn it faster when you try the next time, scientists say.
Using a simple set of experiments, researchers at Johns Hopkins University School of Medicine showed why people learn an identical or similar task faster the second, third and subsequent time around.
They found that people are aided not only by memories of how to perform the task, but also by memories of the errors made the first time.
"In learning a new motor task, there appear to be two processes happening at once," said Reza Shadmehr, a professor in the Department of Biomedical Engineering at the Johns Hopkins.
"One is the learning of the motor commands in the task, and the other is critiquing the learning, much the way a 'coach' behaves.
"Learning the next similar task goes faster, because the coach knows which errors are most worthy of attention. In effect, this second process leaves a memory of the errors that were experienced during the training, so the re-experience of those errors makes the learning go faster," Shadmehr said.
Shadmehr said scientists who study motor control - how the brain pilots body movement - have long known that as people perform a task, like opening a door, their brains note small differences between how they expected the door to move and how it actually moved, and they use this information to perform the task more smoothly next time.
Those small differences are scientifically termed "prediction errors" and the process of learning from them is largely unconscious.
The new study found that not only do such errors train the brain to better perform a specific task, but they also teach it how to learn faster from errors, even when those errors are encountered in a completely different task.
In this way, the brain can generalise from one task to another by keeping a memory of the errors.
To study errors and learning, Shadmehr's team put volunteers in front of a joystick that was under a screen. Volunteers couldn't see the joystick, but it was represented on the screen as a blue dot.
A target was represented by a red dot, and as volunteers moved the joystick toward it, the blue dot could be programmed to move slightly off-kilter from where they pointed it, creating an error.
Participants then adjusted their movement to compensate for the off-kilter movement and, after a few more trials, smoothly guided the joystick to its target.